Octane levels


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By Pete 55Tbird - 5 Years Ago
Since the discussion is about gasoline octane, back in 1961 I bought a 1958 Tbird convertible that had an FE 352 HIPO engine.
This had factory 10.5 compression and a solid cam. I was in Little Rock Ark and you could buy SUNOCO  ( AMACO )unleaded premium
gasoline that had 104 octane. It cost $0.35 per gallon when regular was $0.27 per gallon.
The Tbird refused to run on anything less than 104 with out the timing being retarded.
That was a really great period of American IRON and a lot of fun. Pete
By Pete 55Tbird - 5 Years Ago
miker (1/16/2019)
Ian, back in the day of 10 and 11 to 1 stock motors, and 105-110 octane at some pumps we had that carbon build up problem. I was a teenager in those days (and knew a lot more than I do now), but IIRC, the local mechanic used to dribble water down the carb at high idle, maybe more than idle, maybe 2000 rpm or so. He said the steam broke the carbon loose and it didn’t hurt anything, just blew it out. My Dad’s partner had a 1/2 ton pickup with a Corvette 396 in it (what’s known as a COPO car now), and that’s what I was told they did with it. Hopefully someone with some hands on experience will chime in before you pull the heads.

Miker, your post rings a bell with me. We did dribble water into the carb at fast idle  to de carbon our engines. Clouds of smoke would come out
not unlike an add for SEA FOAM. It did work, as the engine that this was done on did not ping as much and if a head was pulled you could
see how clean it was. Best part was the cost, FREE. Pete
By Pete 55Tbird - 5 Years Ago
ian57tbird (1/17/2019)
Interesting about the water trick!
How long would you do it for and what quantity of water would you expect to use?

Ian, My method was I would dribble water into the carb set at fast idle the idea was to add just enough water to slow the engine BUT NOT KILL IT.
Let the engine recover and repeat until the smoke from the exhaust would stop.
This is not unlike the FAMOUS "ITALIAN TUNE UP" do a Google search. Pete
By KULTULZ - 5 Years Ago
Mine has a dieseling effect when you power brake and try to rev a little but when going down the road and flooring it it diesels for a split second almost cant even notice it and then it gone.


That's interesting as the '56 LOM dual advance chamber (retard feature) was supposed to correct that.

I assume you still have mechanical points and base timing is set @ OEM or has it been bumped? Fuel quality also varies from pump to pump and area to area. How do your plugs read? Your first step may be to use premium fuel (if there is still such a thing). The advance feature within the DIST may also be worn and out of spec.

Make sure secondary IGN is in good shape. You could once put a carburetor car on a drip to break up carbon.
By KULTULZ - 5 Years Ago
It sounds more like a lean tip-in condition. You might consider adjusting the ACCEL PUMP ADJ or possibly going to a larger primary jet.

As for the LOM DIST, the re-builder would have to have a DIST MACH with a manometer, have access to needed parts and know and care what he is doing. The system is unlike a DUAL ADV SYSTEM.

You could plot the DIST ADVANCE CURVE with a timing tape, light and TACH to see if the advance curve is near correct before sending it off. The slight hesitation in advance @ WOT indicates the retard function is working.

As for carbon build-up (which raises CR and interrupts fuel mixture flow) is a given in an engine that old, especially if it ever ran a fat fuel curve or weak IGN.
By KULTULZ - 5 Years Ago
Could there still be engines today with remaining lead deposits from the leaded fuel days?


Well yes as LEAD-FREE GASOLINE became on-line in 72/73 and with the intro of CATS lead additives were made unavailable, except for racing and they ended that also..

So any pre-1975/76 original assembly engine could have lead deposits. That was some nasty stuff but cheap for refiners to raise octane levels.
By KULTULZ - 5 Years Ago
redline lead additive.


RED LINE® LEAD SUBSTITUTE

Should be no need for such a product for a street engine (IMO of course).
By KULTULZ - 5 Years Ago
Damn, it’s hard being 69 and not knowing as much as I did when I was 17.


Eh, you're just a pup ...
By KULTULZ - 5 Years Ago
Phase Separation describes what happens to gasoline containing Ethanol when water is present. When gasoline containing even small amounts of Ethanol comes in contact with water, either liquid or in the form of humidity; the Ethanol will pick-up and absorb some or all of that water. When it reaches a saturation point the Ethanol and water will Phase Separate, actually coming out of solution and forming two or three distinct layers in the tank.


REQUIRED READING- http://fuelschool.blogspot.com/2009/02/phase-separation-in-ethanol-blended.html

Also -

Further the federal government currently subsidizes Ethanol with a $.51 per gallon tax credit that goes to the refiners or blenders. With E-10 this provides those refiners and or blenders with a $.051 per gallon subsidy on every gallon of gasoline that they sell.

In many cases we have seen gasoline containing more than 10% Ethanol. We test regularly and have seen fuel containing 12%, 13%, and even 14% Ethanol while the pump shows only 10%. Increasing the amount of Ethanol increases the refiner/blenders subsidy and profit while further lowering your fuel economy.
By KULTULZ - 5 Years Ago
...humid areas such as Houston will result in a reduction in octane in a shorter period of time...


Yes as the octane additive(s) is in the methanol-


http://forums.y-blocksforever.com/uploads/images/a7e2f793-ce85-4173-bd43-95a6.png

And the same will happen in the CARB fuel bowl(s) as they are open vented also.

I think the first line of defense (other that non-ethanol gasoline or EVAP) is to have a drain at the bottom of the gas tank to draw water off at intervals,
By miker - 5 Years Ago
Ian, back in the day of 10 and 11 to 1 stock motors, and 105-110 octane at some pumps we had that carbon build up problem. I was a teenager in those days (and knew a lot more than I do now), but IIRC, the local mechanic used to dribble water down the carb at high idle, maybe more than idle, maybe 2000 rpm or so. He said the steam broke the carbon loose and it didn’t hurt anything, just blew it out. My Dad’s partner had a 1/2 ton pickup with a Corvette 396 in it (what’s known as a COPO car now), and that’s what I was told they did with it. Hopefully someone with some hands on experience will chime in before you pull the heads.
By miker - 5 Years Ago
Ian, it was along the lines of a cup or a pint IIRC. Made a great deal of steam, and not so much to kill the engine. But it’s been years, and I don’t remember if I ever did it, watched, or just heard the story.

Having had a 11.25:1 312 in those days I do remember the lead fouling on the spark plugs, and deposits on the valves, but I didn’t know what caused them on the valves. Damn, it’s hard being 69 and not knowing as much as I did when I was 17.
By Lord Gaga - 5 Years Ago
Amid mounting calls to phase out fossil fuels in the face of rapidly worsening climate change, the United States is ramping up oil and gas drilling faster than any other country, threatening to add 1,000 coal plants’ worth of planet-warming gases by the middle of the century, according to a report released Wednesday.
 By 2030, the U.S. is on track to produce 60 percent of the world’s new oil and gas supply, an expansion at least four times larger than in any other country. By 2050, the country’s newly tapped reserves are projected to spew 120 billion metric tons of carbon dioxide emissions into the atmosphere.

SO WHY BOTHER WITH CORN? FARM SUBSIDIES!
By Lord Gaga - 5 Years Ago
DYI Ethanol free gasoline;
https://www.youtube.com/watch?v=QH2zgomFdEM
I can see this as a winter project for those of us in cold climates and on a tight fuel budget!  Use 5 gallon ex-water bottles, start with 93 octane. The dye in the water is crucial. Get some 55 gal drums for storage. How about it? w00t
(Don't be like this guy and do it near an open flame or source of spark...hot water heater behind him!) Wow
By FORD DEARBORN - 5 Years Ago
Same thing going on in Michigan. Went from 31 MPG to 28 with the Focus and 18 down to 16 with the F150. Gasoline is much cheaper but were burning more fuel. Sometime earlier last year I read about a plan  to offer only one grade of fuel. Like, eliminate mid grade and regular.  The added alcohol can improve the fuel's resistance to knock?  I can't find this information so take it with a few grains of salt or maybe someone else can comment.  We can re-jet our carburetors for additional alcohol content but neoprene parts would last even less time and more water vapor would condense in a given time in an open fuel systems.  I haven't yet done an alcohol test but will soon and report my findings. JEFF.....................
By FORD DEARBORN - 5 Years Ago
There is only one non-alcohol fuel retailer near me but it costs about a whopping 70 cents more/gal in my area.  I have tried it in all my vehicles including my modern daily drivers and small engine appliances. Every engine loves it. Like, engines will give you a big hug for feeding them that stuff.  Several years ago I tested it for alcohol and found none, at that time. As far as what it is?  I'm guessing it may use av-gas as its base stock with out the lead, of course. I remember very well what 100LL smells like from my aviation days and the non-alcohol fuel has a hint of that "sweet" smell like av gas. Non-alcohol fuel doesn't have that nasty smell and the exhaust smell is much better. Since refineries are still producing av gas for piston engine aircraft, it would make sense to possibly use that stock for non-alcohol fuel IMHO.  If it were reasonably priced and available more places, we and our Y-blocks would have it made in the shade.  
By FORD DEARBORN - 5 Years Ago
Very interesting, hopefully someone with more fuel chemistry smarts than I will comment. Isn't the alcohol used to support the octane number advertised on the pump? Removing the alcohol would seem to bring the fuel close to "white gas" which may be ok for small engines. Not sure how this would play out for our classic engines. I do have a friend who built a screaming strictly race (stroker 351+) vehicle running on pure (neat) alcohol very successfully. He claims higher compression ratios and very predictable 1/4 mile times but burns almost double the fuel. Looking at the carburetor jets tempts me to see if a pencil will fit.
By FORD DEARBORN - 5 Years Ago
Florida_Phil (1/17/2019)
On this subject, here's an interesting side note.  When I put the 1957 G heads on my motor, I took them to my machine shop.  These people do a lot of work for local racers and they have been around for a long time.  I asked the machinist if I needed to install hardened valve seats in my heads.  He told me the alcohol in the today's fuel makes this unnecessary.  My car is only driven slightly, so I did not pursue this any further.  Anyone have an opinion on this?

IMO, you will not have issues with the valves/seats. The engine will not be under long time high stress such as constant heavy load/stress as might be the case with heavy truck duty of racing. Twenty some years on a mild 289 build I just couldn't see cutting away the original pristine seats in these particular heads. There has been no reported issues. An added benefit is the exhaust valves should run a little cooler due to better heat transfer through the integral seat, for what that's worth.  Again, just my opinion, JEFF........................
By FORD DEARBORN - 5 Years Ago
miker (1/16/2019)
Ian, back in the day of 10 and 11 to 1 stock motors, and 105-110 octane at some pumps we had that carbon build up problem. I was a teenager in those days (and knew a lot more than I do now), but IIRC, the local mechanic used to dribble water down the carb at high idle, maybe more than idle, maybe 2000 rpm or so. He said the steam broke the carbon loose and it didn’t hurt anything, just blew it out. My Dad’s partner had a 1/2 ton pickup with a Corvette 396 in it (what’s known as a COPO car now), and that’s what I was told they did with it. Hopefully someone with some hands on experience will chime in before you pull the heads.

I too have heard of this often used water dribbled down the carb throat but also, back in the day, the fuel contained lead which always formed hard/crusty deposits. On performing valve work, it often wan not necessary to replace the exhaust valves but the hard lead salts would mound up on the underside of the valve head and had to be chipped away before grinding. This type of deposit I don't think would be too easily removed otherwise. Could there still be engines today with remaining lead deposits from the leaded fuel days?
By ian57tbird - 5 Years Ago
We don't subsidise the corn farmers over here in Australia so thankfully we don't have the alcohol in our fuel.
Getting back to the original question about detonation. I have a 1989 Landcruiser with original untouched engine that I have owned for about 18 years. It ran fine on regular unleaded in the early days, but over the years started to develop detonation under load, especially with the higher temperatures. I am now running high octane unleaded equal to your 93. I have checked mixture under load and advance curve. About the only thing left in my mind is carbon build up. Not looking forward to pulling the head.
By ian57tbird - 5 Years Ago
Interesting about the water trick!
How long would you do it for and what quantity of water would you expect to use?
By Rusty_S85 - 5 Years Ago
Question, what octane level are people running in their stock Y`s?

Mine has a dieseling effect when you power brake and try to rev a little but when going down the road and flooring it it diesels for a split second almost cant even notice it and then it gone.

Im wondering if the 87 octane regular I am running is just not up to par.

Either that or I need to back timing off some but I never had a too advance engine act like this one is so I am wary if this is the cause.

Only other option I could think of is maybe carbon build up from running the engine at idle over the years till I got to this point.

Anyways just curious what other people are running octane wise.  Might need to upgrade to middle grade on this old engine as that is 89 octane around here.
By Rusty_S85 - 5 Years Ago
Florida_Phil (1/12/2019)
I have wondered about this myself.  Most stock Y Blocks are not high compression engines.  My 1955 292 has been bored .060, squared, decked and align honed with flat top pistons and no valve reliefs. It's running stock 1957 G heads that have had the surfaces cleaned up with no excessive milling and composite FelPro head gaskets. I also have a 1957 distributor in this engine with 10 degrees advance on the crank and 38 degrees total timing.  I use 93 octane pump gasoline.  This engine runs great and does not run on or knock.   Should I use high test?


Same here, I typically run the regular grade fuel but we got that stupid ethanol blend around here, once I move I can get 93 octane in straight gas which I will go with.  But here I can get 87 Octane regular, 89 Octane premium, or 93 Octane super.  Ive been putting 87 octane regular in here cause of the low compression and that's what I run in my 302 in my '82 truck that has the same compression ratio along with in my 351W in my '78 Mercury.  But this is acting a bit different which could be due to points and the lack of mechanical advance.

The ignition system I replaced it completely about 3 or 4 years ago but I haven't drove the car just ran it from time to time while I did other work on the car.  The plugs, plug wires, point, condenser, cap, rotor are all new basically with limited use.  The dist how ever is original to the car and from all the service records I have in my grandfathers notebook that was in the ash tray there is no mention of replacing the dist as far back as 1963 so I assume this is original from 1956 and has never been pulled.

KULTULZ (1/12/2019)
Mine has a dieseling effect when you power brake and try to rev a little but when going down the road and flooring it it diesels for a split second almost cant even notice it and then it gone.


That's interesting as the '56 LOM dual advance chamber (retard feature) was supposed to correct that.

I assume you still have mechanical points and base timing is set @ OEM or has it been bumped? Fuel quality also varies from pump to pump and area to area. How do your plugs read? Your first step may be to use premium fuel (if there is still such a thing). The advance feature within the DIST may also be worn and out of spec.

Make sure secondary IGN is in good shape. You could once put a carburetor car on a drip to break up carbon.





Timing is bumped up to 12* initial which at idle in neutral it is 16* with the vacuum lines attached.  I saw the timing go retard when I hit the throttle fairly hard from an idle when I was checking the dist operation.

I haven't pulled the plugs to read them but the whole ignition system was replaced minus the dist about 4 years ago.  But mind you the car hasn't been driven in those 4 years just idling and a few revs here and there just to maintain the battery as I worked on other aspects of the car.

Im wondering if its just bad weak gas that is truly not 87 octane or if its carbon buildup or if its something else.  I did turn my idle mixture screws out half a turn at a time and the knocking dieseling feel got better.  at 1 turn out from where it was on both screws the engine now doesn't stumble but I can hear a knock for a moment on the initial hit of the throttle.  but loading the engine up its running a little rough but no sound of a knock like it does when you first hit the throttle with the brake applied.


charliemccraney (1/12/2019)
When you say stock, are you talking about an engine that has never been apart or had any significant work since it left the factory.  Or is it an engine that has been rebuilt, trying to keep it as close to stock specs as possible?  There can be significant differences, depending on who did the rebuild and the attention to detail.


Correct, stock as in the engine has never been apart as far as I know.  Only work that's been done on it was pulling the intake to put a newer 2V intake and late model 2V carb on it which I  pulled off and reinstalled the original 4V intake that came off the carb and a reman holley 4000 along with a NOS dual reservoir vacuum advance.

Im kind of wondering if it was carbon build up I don't think its advance because the engine spins over too easily with the starter to be too far advanced.  I currently have timing set at 12* initial which is 16* at full idle with the venturi and manifold vacuum lines attached.  Reving the engine I saw it advance smoothly with a rev and when I hit it quite hard to nearly full throttle I saw the TDC mark quickly fall back behind the pointer for a split moment before it went back to around 30* advance at around 2,000 rpm I guestimate.

Tedster (1/12/2019)
Rusty, I have experimented some with tuning and carburetion and found a stock Y Block will tolerate a fair amount of ignition advance over and above the stock specs due to the lower compression, this was true by 1964 in the truck engines at least, with their 8 to 1 ratio. Fuel quality is not critical by any stretch. The factory spec was 6° BTDC base timing at that time, and further allowed another 5° for high altitude or to optomize performance and economy. So 11° BTDC was the initial timing spec for a stock truck curve. A car being generally lighter would likely tolerate even more if you play around with the curve and springs with a post '56 distributor. Some people run close to 40° on a stock Y Block, regardless of the number give it what it wants and don't worry about the number, if it isn't knocking or detonating. Keep in mind too, engine knock isn't necessarily audible!

Running lots of ignition advance, lean fuel mixtures, and electronic ignition may benefit from a slightly cooler heat range spark plug to minimize engine knock due to hot spots. I would believe you've got something else going on other than fuel octane. Keep an eye on the plug ceramic for evidence of detonation though, excessive advance can burn holes in pistons and other fun stuff. A small amount of spark knock on occasion during part throttle acceleration is not a cause for concern. Tuning is an art as well as a science!

A worn distributor will cause trouble with this for example, excessive distributor cam wobble will require detuning the engine to prevent knock. Excessive carbon buildup will do it. I found using both a wideband O2 sensor for carburetor adjustment and an ignition scope really upped my tuning game, it's remarkable how far out of tune something can get and still run reasonably well.


That is what I am concerned with is if it might be my old dist.  I did turn my idle mixture screws out half a turn equally and putting car in drive and stepping on the gas it got better, wasn't shaking as bad and wasn't dieseling as bad.  Went another half turn out on both screws and its gotten better it actually tries to pull.  I can feel transmission slipping in second gear so that is probably my problem on the transmission falling out of gear, a band that is worn out, needs adjustment, or a leaky servo not applying enough line pressure.  But the car pulls now and doesn't shake dieseling but it is still knocking for a split moment when I first hit the throttle.  if I load the engine up like checking for a miss it doesn't knock it just knocks on the initial hit of the throttle.

I thought about going another half turn out on the idle screws but I don't know how far out they are now and don't want to have them fall out.  Like wise I don't know if another half turn out will remove the initial knock that is there.  I did get the stumble out and the roughness out.  Guess I had the carb set ideally and not slightly rich like is wanted so with the air filter on it made a change.  I know I put my hand over the choke housing to check for a lean condition when I initially set the carb idle mixture and it didn't race up like it was running lean it stayed idled the same with no change indicating an ideal mixture.

I guess what I will need to do is look at getting this dist rebuilt and then go from there.  I got just under 3/4 of a tank not sure how quickly I can burn that out to get some 93 octane in there to see if that is the cause that I have now.
By Rusty_S85 - 5 Years Ago
KULTULZ (1/12/2019)
It sounds more like a lean tip-in condition. You might consider adjusting the ACCEL PUMP ADJ or possibly going to a larger primary jet.

As for the LOM DIST, the re-builder would have to have a DIST MACH with a manometer, have access to needed parts and know and care what he is doing. The system is unlike a DUAL ADV SYSTEM.

You could plot the DIST ADVANCE CURVE with a timing tape, light and TACH to see if the advance curve is near correct before sending it off. The slight hesitation in advance @ WOT indicates the retard function is working.

As for carbon build-up (which raises CR and interrupts fuel mixture flow) is a given in an engine that old, especially if it ever ran a fat fuel curve or weak IGN.

I will need to look at the carb manuals I have, I don't know if the accelerator pump can be adjusted or not on this Holley 4000 I never looked.

I know on my truck I went one notch up it removed some of the stumble but not all.  I got most of the stumble out but thought maybe its not squirting enough fuel that could be why I can off set it with fattening up the idle circuit.

Maybe best to see my old carb that came off here see where its accelerator pump is set at and check this reman holley 4000 and see if its in the same place.
By Rusty_S85 - 5 Years Ago
I just looked, my old Holley 4000 is set on the bottom most hole which is from what I am reading the summer setting.

The Holley 4000 I paid a core on to get a spare to use for now it is also set on the summer setting in the bottom hole.

Im tempted to take and move the accelerator pump rod up to the winter setting and resetting my idle mixture back where I had it at and see how it does then.  Could very well be a lack of fuel cause I know when I was trying to drive the car I was fluttering the gas pedal to get the car to move off the line like it just wouldn't take any gas like it was running out of fuel.

Might very well be the accelerator pump isn't giving me enough fuel squirt to make it run right.  Might still need to leave the idle mixture where they are at but I rather revert the changes I made and see what changes just the accelerator pump made and then go from there.
By Rusty_S85 - 5 Years Ago
Im going to have to play around with it more.  I set the pump shot to the winter setting.  I then returned the idle mixture screws where I had it set at which was just barely rich enough that placing my hand over the choke plates did not create a increase in RPM like it was running lean.

I power braked it a but and the engine was knocking like crazy.  I took and did half a turn again to 1 1/2 turns out and the knock pretty much went away except for a slight knock at tip in that I could barely hear.  I figured ok let me go drive it.

Hit the throttle in first gear since the transmission obviously now needs a rebuild.  Well engine lays down then picks up which in my experience has always been not enough fuel.  but where this is different is the engine shakes from knocking so I am now starting to wonder if its simply the 87 octane gas I have in there is truly not 87 octane.  but the engine knocks with any kind of load on it but yet it wasn't knocking when you would power brake it hitting the throttle which is more load than pulling the vehicle.

Going to wait till I get the transmission rebuilt first then I will play around with it more.  If I cant seem to get it to straighten out I might just call it quits and snatch the engine out and rebuild it.
By Rusty_S85 - 5 Years Ago
Tedster (1/13/2019)
Rusty, it stands to reason that since your other vehicles don't knock on 87 octane, the '56 should do just fine. You mentioned not having driven it in several years, I wasn't aware of that. It may be the fuel in the tank has started to sour or undergo what's called phase separation and go bad.


The tank was replaced but the fuel in it was down to a 1/4 tank with some stabil 360 in the tank it was a little over the protection date but I added 10 gallons of 87 octane so I am now at 3 quarts of a tank.  This was back in October when this was done with 2 oz I believe it was of stabil 360 added to the fuel.

Im tempted to pull the plug on the fuel tank and drain what I can and just go get 10 gallons of 93 and put in there and see if that makes a positive change.
By Rusty_S85 - 5 Years Ago
At work we do ATF but that is mostly done to try and get rings unstuck.  weve also used that AC Delco top end cleaner in concentrate form and pour it down the intake as well then stall the engine out with it and let it sit in the cylinders for a bit.  Problem is not sure how you would do something like that with a HOlley 4000 with the primary barrels shrouded by the choke assembly and fuel bowl.   Guess you could dump it down the secondaries.
By Rusty_S85 - 5 Years Ago
Interesting.  Reading ive done said that microwelds happen under load when accelerating without lead.

Wonder if I need to even be using the expensive redline lead additive.

I did grab a bottle from work of that STP race series of octane booster.  No cost to me but now I need to do some reading on it find out if its something I want to attempt to use on my 292 to try and starve off spark knock I have.
By Rusty_S85 - 5 Years Ago
Yep, I did a little reading during lunch the stuff I got its not that great so I will probably take and give it back to the customer that gave it to me since I wont use it.  I did see Torco F500010TE ranked #1 on best octane booster for 2018 it boasts up to a 14 point octane increase depending on how you mix it.  Claims a bottle of this stuff in 10 gallons can turn 91 octane into 102 octane.  Something for me to keep in mind but I am going to run 93 and try that.  Just not sure if the 93 here is truly 93 or if its just being sold as 93 and its sucking from the same 83 octane tank
By Rusty_S85 - 5 Years Ago
KULTULZ (1/19/2019)
Phase Separation describes what happens to gasoline containing Ethanol when water is present. When gasoline containing even small amounts of Ethanol comes in contact with water, either liquid or in the form of humidity; the Ethanol will pick-up and absorb some or all of that water. When it reaches a saturation point the Ethanol and water will Phase Separate, actually coming out of solution and forming two or three distinct layers in the tank.


REQUIRED READING- http://fuelschool.blogspot.com/2009/02/phase-separation-in-ethanol-blended.html

Also -

Further the federal government currently subsidizes Ethanol with a $.51 per gallon tax credit that goes to the refiners or blenders. With E-10 this provides those refiners and or blenders with a $.051 per gallon subsidy on every gallon of gasoline that they sell.

In many cases we have seen gasoline containing more than 10% Ethanol. We test regularly and have seen fuel containing 12%, 13%, and even 14% Ethanol while the pump shows only 10%. Increasing the amount of Ethanol increases the refiner/blenders subsidy and profit while further lowering your fuel economy.





Yep I deal with phase separation at work all the time.  even with something like stabil in the tank it wont phase separate but you can still smell the ethanol has gone bad.

Which has me wondering on vented gas tanks that are vented straight to the atmosphere such as on Fords of this era with a fuel tank vent that vents behind the license plate if humid areas such as Houston will result in a reduction in octane in a shorter period of time.  That is why I been running the stabil 360 which says it stabilizes ethanol but I just haven't found anything concrete on if it makes much of a difference other than preventing phase separation or not.

Wish the cold front wasn't still moving through here I would like to drain my tank today and get some fresh 93 octane and put in, that is if my local gas station is selling 93 octane and it just isn't regular old 87 being sold as 93.
By Rusty_S85 - 5 Years Ago
Well I finally got some good weather to get the gas out and put fresh in.  The gas that came out it wasn't bad but it was yellowed none the less which means it is aged quite a bit.

I drained as much as I could out and put just 5 gallons of straight 93 octane in the tank.  Fired the car off and ran a bit wonky as it was coughing every now and then in the exhaust with a miss felt in the body.  After running for a bit the old gas got out of the carb and the fuel pump to the point that it was running on fresh 93 octane.  I power braked the car and hit the gas a bit reving it to see if I could force it to spark knock for a bit cause it would spark knock for a split second before after I enriched the fuel mixture on the accelerator pump to the winter setting.  I did it this time and I physically heard no spark knock at all.  I didn't drive the car but I will give it a try when the weather clears up again and see if its still knocking when accelerating for driving.  I think I might have resolved it cause before I could hear a faint knock in the engine when running with no load it was probably the old gas pinging on me cause now I don't hear it, I just hear the rockers clicking faintly.
By Rusty_S85 - 5 Years Ago
Im going to drain the tank this weekend. More i think of it i suspect weak fuel is the cause.

It slipped my mind but when you start the car up on a cold fast idle it knocks and does a muffled puff sound in the exhaust like a cough.

Even warmed up i think i faintly hear it at idle as well.

I know the gas isnt old but i suspect mixing 10 gallons with some old gas with stabilizer didnt weaken the fuel. Or maybe the station is not selling true 87 octane.

Going to pull the plug and drain what i can and refill with 93 octane. No point chasing my tail trying to figure this out without starting with the fuel itself first.
By Rusty_S85 - 5 Years Ago
Ted (1/14/2019)
As a general rule, I use premium fuel in all my carbureted vehicles simply due to the reduced ethanol content in premium versus the 85 and 87 octane grades.   Even my ’50 Ford with a Flattie gets a regular diet of premium grade gasoline.  Unless driving the vehicles regularly, I keep the gas tanks on the low side so the fuel can be constantly refreshed.  The reduced ethanol content by itself will increase the shelf life of the gasoline.

With this engine not being apart before I run that lead additive did my research and got the Redline stuff as it didn't have bad reviews like the others causing valves to hang up.

Anyways that's why I run a full tank cause its one bottle to a tank and I hate the thought of wasting a whole bottle on just 5 gallons of gas.  The Stabil 360 that is no problem that I have the big bottle that has the oz marks to add the right amount.  Not the same with the stabil.

I think I am going to just pull the plug and swap the fuel over to 93.  Price is more but I will pay more to eliminate this spark knock.  If I can get it eliminated then I might be able to play with my idle jets some more to hopefully get the stumble on acceleration out.
By Rusty_S85 - 5 Years Ago
Ted (1/15/2019)
I find that the Holley 4000 carbs (Teapots) are overly sensitive to ethanol laden gasoline and require up to a two number increase in jetting in which to compensate if using 91-93 octane fuel.  If using 85-89 octane fuel, the problem will just be worse as the lower octane fuels have a higher percentage of ethanol in the gasoline than the 91-93 octane grades.
 
The first symptom of the lean jetting in those carbs is a hesitation right off of idle and on the more worse situations, a lag in part throttle response where the engine seems sluggish or not wanting to take the fuel.  The increase in primary jetting fixes both of these.  I’m fortunate that I can ‘drive’ some of these engines on the engine dyno and simulate actual driving conditions.  With that information and computer generated data, the jetting is corrected before the engine goes in the vehicle.


That sounds like whats going on with me.  Car couldn't even pull itself up the driveway if I put the back tires in the gutter of the driveway.  That hump just caused the motor to bog down and not pull itself up.  I had to get a running start.  Think this fuel is my problem cause around here its up to 15% ethanol and the fuel only lasts about 2 months before it goes bad without stabil in it.

Im going to just dump my tank and get some 93 octane and run that.  I don't know what jets are in this carb but this carb is listed as being for a 312 and its on a 292 right now so the jetting should be a bit fatter than usual.  Car runs great its just is sluggish off idle, going to the richer winter setting on the accelerator pump did take some of the hesitation out but there is a moment where it goes flat and picks up.  I can step down on the throttle harder and it doesn't hesitate as bad.

I am going to try and pull a plug out tonight after work if its not raining just to check it and see what it looks like on number one.
By Rusty_S85 - 5 Years Ago
FORD DEARBORN (1/15/2019)
Same thing going on in Michigan. Went from 31 MPG to 28 with the Focus and 18 down to 16 with the F150. Gasoline is much cheaper but were burning more fuel. Sometime earlier last year I read about a plan  to offer only one grade of fuel. Like, eliminate mid grade and regular.  The added alcohol can improve the fuel's resistance to knock?  I can't find this information so take it with a few grains of salt or maybe someone else can comment.  We can re-jet our carburetors for additional alcohol content but neoprene parts would last even less time and more water vapor would condense in a given time in an open fuel systems.  I haven't yet done an alcohol test but will soon and report my findings. JEFF.....................


Same thing I noticed here, my old 82 F150 when I was still driving it went from 15 mpg city down to 12 mpg city after the switch to this ethanol blend.  Sad thing is winter is worse I get about 9 to 10 mpg city in winter.  With the regular gas used to get 14-15 year round.

Once I move there is a gas station small one in a small town that sells ethanol free 93 octane at nearly $3 a gallon.  Im thinking about just running that to get my mileage back as well as to help out my old vehicles run better.
By Rusty_S85 - 5 Years Ago
FORD DEARBORN (1/16/2019)
There is only one non-alcohol fuel retailer near me but it costs about a whopping 70 cents more/gal in my area.  I have tried it in all my vehicles including my modern daily drivers and small engine appliances. Every engine loves it. Like, engines will give you a big hug for feeding them that stuff.  Several years ago I tested it for alcohol and found none, at that time. As far as what it is?  I'm guessing it may use av-gas as its base stock with out the lead, of course. I remember very well what 100LL smells like from my aviation days and the non-alcohol fuel has a hint of that "sweet" smell like av gas. Non-alcohol fuel doesn't have that nasty smell and the exhaust smell is much better. Since refineries are still producing av gas for piston engine aircraft, it would make sense to possibly use that stock for non-alcohol fuel IMHO.  If it were reasonably priced and available more places, we and our Y-blocks would have it made in the shade.  

Bunch of stations listed here that sells ethanol free fuel.  Problem is though city is quite large and I don't know if I want to drive that far just to get some ethanol free gas.

There is a Exxon, Conoco, and a Phillips fairly close to me that is listed as having ethanol free gas.  But still its at least a 3 mile drive one way to get to those stations for me.

Correction only one in the city that has it and they sell it by 5 gallon pails as they only sell race fuel.  The ones coming up were popping up just cause they are gas stations not because they were ethanol free.
By Rusty_S85 - 5 Years Ago
Tedster (1/16/2019)
I don't have fuel chemistry smarts but Ethanol was used to replace stuff called MTBE, whose purpose was to meet a federal mandate for oxygenated fuels. MTBE was banned however due to groundwater contamination issues, it's nasty stuff once it percolates into the water table, and it is persistent. So ethanol sort of makes sense as far as that goes, and it also increases octane. But it runs leaner and has other well known problems. I wonder what the percentage of ethanol is really needed to meet those requirements compared to what they are actually using. It's a very noticeable fuel economy decline even at 10%.


Its a considerable economy decrease, around here we have stickers saying contain up to 15% ethanol and my economy in my old truck went from 15 city to 12 city after they made the switch here.

Closest ethanol free station to me would be the buccees in Katy and I am not going to drive nearly 20 miles one way to that station to buy ethanol free.  I will just buy the 93 to see if I can get the knocking to go away and if not then I might need to play with jetting.  I don't think I need to how ever considering this carb is listed as for a 312 which I was told by the guy that restores these holley 4000`s that they are jetting bigger than the holley 4000 listed for the 292.
By Florida_Phil - 5 Years Ago
I have wondered about this myself.  Most stock Y Blocks are not high compression engines.  My 1955 292 has been bored .060, squared, decked and align honed with flat top pistons and no valve reliefs. It's running stock 1957 G heads that have had the surfaces cleaned up with no excessive milling and composite FelPro head gaskets. I also have a 1957 distributor in this engine with 10 degrees advance on the crank and 38 degrees total timing.  I use 93 octane pump gasoline.  This engine runs great and does not run on or knock.   Should I use high test?
By Florida_Phil - 5 Years Ago
I fought a similar issue for some time.  My engine seemed perfect.  Brand new rebuild with Pertronix igntor, new carb, the works.  Still, the darn thing wouldn't idle consistently and I had an intermittent miss. Finally pulled the gas tank.  When I looked inside the entire bottom of the tank was covered with rust.  It was getting by my fuel filter and clogging up the carb.  I put in a new gas tank and the car runs perfectly. No more miss, lots more power and no more headaches.  $150 well spent.
By Florida_Phil - 5 Years Ago
Those old HiPo FE motors had tiny combustion chambers.  I had a 406 6V Galaxie and I had to run high test with a can of lead additive.  I'm pretty sure it wouldn't run on today's gas.
By Florida_Phil - 5 Years Ago
On this subject, here's an interesting side note.  When I put the 1957 G heads on my motor, I took them to my machine shop.  These people do a lot of work for local racers and they have been around for a long time.  I asked the machinist if I needed to install hardened valve seats in my heads.  He told me the alcohol in the today's fuel makes this unnecessary.  My car is only driven slightly, so I did not pursue this any further.  Anyone have an opinion on this?
By Tedster - 5 Years Ago
Rusty, I have experimented some with tuning and carburetion and found a stock Y Block will tolerate a fair amount of ignition advance over and above the stock specs due to the lower compression, this was true by 1964 in the truck engines at least, with their 8 to 1 ratio. Fuel quality is not critical by any stretch. The factory spec was 6° BTDC base timing at that time, and further allowed another 5° for high altitude or to optomize performance and economy. So 11° BTDC was the initial timing spec for a stock truck curve. A car being generally lighter would likely tolerate even more if you play around with the curve and springs with a post '56 distributor. Some people run close to 40° on a stock Y Block, regardless of the number give it what it wants and don't worry about the number, if it isn't knocking or detonating. Keep in mind too, engine knock isn't necessarily audible!

Running lots of ignition advance, lean fuel mixtures, and electronic ignition may benefit from a slightly cooler heat range spark plug to minimize engine knock due to hot spots. I would believe you've got something else going on other than fuel octane. Keep an eye on the plug ceramic for evidence of detonation though, excessive advance can burn holes in pistons and other fun stuff. A small amount of spark knock on occasion during part throttle acceleration is not a cause for concern. Tuning is an art as well as a science!

A worn distributor will cause trouble with this for example, excessive distributor cam wobble will require detuning the engine to prevent knock. Excessive carbon buildup will do it. I found using both a wideband O2 sensor for carburetor adjustment and an ignition scope really upped my tuning game, it's remarkable how far out of tune something can get and still run reasonably well.
By Tedster - 5 Years Ago
For a stock street engine that does a lot of stop & go or just off idle acceleration, the mixture setting is important. Most driving is done there.

It's called the idle circuit but the throttle plate exposes the transition slot "just so" when the RPM and mixture is set just right. It's probably in play up to around 40 miles an hour. It needs to be set just slightly rich from a point that is just about as lean as you can get it consistent with a smooth idle. If you start cranking on the screws it will be way off. They are "precision cut", about an 1/8 turn on a single screw changes the engine AFR by a whole point.

Lean out the idle mixture and fatten up the pump shot. It sounds counterintuitive but that's how it works. Too much pump shot can cause a bog or hesitation too.
By Tedster - 5 Years Ago
Rusty, it stands to reason that since your other vehicles don't knock on 87 octane, the '56 should do just fine. You mentioned not having driven it in several years, I wasn't aware of that. It may be the fuel in the tank has started to sour or undergo what's called phase separation and go bad.
By Tedster - 5 Years Ago
I don't have fuel chemistry smarts but Ethanol was used to replace stuff called MTBE, whose purpose was to meet a federal mandate for oxygenated fuels. MTBE was banned however due to groundwater contamination issues, it's nasty stuff once it percolates into the water table, and it is persistent. So ethanol sort of makes sense as far as that goes, and it also increases octane. But it runs leaner and has other well known problems. I wonder what the percentage of ethanol is really needed to meet those requirements compared to what they are actually using. It's a very noticeable fuel economy decline even at 10%.
By Tedster - 5 Years Ago
I'm no expert, but I've read - not sure about this - but a carburetor is jetted for a certain flow or fuel curve and as such would not need rejetting when installed on a different size engine. So you might be right. On the other hand, looking at the charts the manufacturers jetted what appears to be the same size carburetor with quite a spread of jet size over the years depending on application. A wideband O2 sensor is interesting to use and experiment with jetting and carburetor tuning. Even with modern equipment though the plugs need to be looked at very carefully.
By Hoosier Hurricane - 5 Years Ago
Ted, late news releases in my farm paper talks about Trump wanting to switch to E15 gas year 'round instead of winter only.  You had bad gas at the Engine Masters, did they supply you with local pump gas?  My race car ran 12.0s at the beginning of the season with last year's gas still in the tank.  Then after I filled it with fresh 93 octane, it slowed to 12.5s, slowed from 112 mph to 106.  I couldn't find anything mechanically wrong, so I performed a crude alcohol test of the gas in the car, and sure enough, it checked well over 10%, nearly 15%.  My local Marathon guy assured me that they never have more than 10% in any of their three grades of gasoline.  Then I noticed that local gas pumps no longer have stickers on them saying they have 10% alcohol like they used to.  No stickers at all.  The fresh gas I put in in the spring was probably remaining "winter" 15% gas.  Also, my 2014 Chrysler van dropped from almost 22 mpg last summer to about 18.5 since September.  The supposed 15% gas was said to run from September to June.
By Hoosier Hurricane - 5 Years Ago
My local Marathon guy also told me that he has 90 octane non-alcohol gas available.  He said he sells it to other local farmers for their chain saws, lawn mowers, 4 wheelers, and older gasoline tractors.  He said they love it.  He'll deliver it to me if I have a drum he can pump it into.  Didn't quote a price.  Makes me wonder what new "stuff" is in the furnace oil I get from him?????  I suspect soy bean oil like they are making diesel fuel from now.

The Midwest farmers love the idea of E15 year 'round.  They grow more corn that ever, and there are a lot of ethanol plants around here.
By Hoosier Hurricane - 5 Years Ago
The racing alcohol is METHANOL, not ethanol.  My buddy using it in his big engine drag car used 3 times as much as he did gasoline.
By charliemccraney - 5 Years Ago
When you say stock, are you talking about an engine that has never been apart or had any significant work since it left the factory.  Or is it an engine that has been rebuilt, trying to keep it as close to stock specs as possible?  There can be significant differences, depending on who did the rebuild and the attention to detail.
By charliemccraney - 5 Years Ago
Most octane boosters are misleading.  They'll boast something like a 10 point increase.  So you'll think awesome, that makes my 87 a 97.  Nope.  Read the back of the bottle and 1 point is 1/10 of an octane number.  So the 87 will be 88.  In this case, you're probably better off to simply try the next grade of fuel.
By Ted - 5 Years Ago
As a general rule, I use premium fuel in all my carbureted vehicles simply due to the reduced ethanol content in premium versus the 85 - 89 octane grades.   Even my ’50 Ford with a Flattie gets a regular diet of premium grade gasoline.  Unless driving the vehicles regularly, I keep the gas tanks on the low side so the fuel can be constantly refreshed.  The reduced ethanol content in the premium grades of fuel by itself will increase the shelf life of the gasoline.
By Ted - 5 Years Ago
I find that the Holley 4000 carbs (Teapots) are overly sensitive to ethanol laden gasoline and require up to a two number increase in jetting in which to compensate if using 91-93 octane fuel.  If using 85-89 octane fuel, the problem will just be worse as the lower octane fuels have a higher percentage of ethanol in the gasoline than the 91-93 octane grades.
 
The first symptom of the lean jetting in those carbs is a hesitation right off of idle and on the more worse situations, a lag in part throttle response where the engine seems sluggish or not wanting to take the fuel.  The increase in primary jetting fixes both of these.  I’m fortunate that I can ‘drive’ some of these engines on the engine dyno and simulate actual driving conditions.  With that information and computer generated data, the jetting is corrected before the engine goes in the vehicle.