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By slumlord444 - 9 Years Ago
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There was a post some time back that this helps cooling on the T-Birds. I believe they said use a 3/8 pipe plug with a 1/8" hole drilled in it. Do I have this right? Not sure of the hole size.
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By GREENBIRD56 - 9 Years Ago
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1/8 inch diameter - that will do just fine - the brass 3/8 pipe plug will then screw into the short 5/8 hose coming out of the t-stat housing. Simply changes the amount of water that bypasses the radiator and recirculates "hot". Works on any of the engines - not just the T-birds.
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By DryLakesRacer - 9 Years Ago
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Worked for me, Along with a smaller water pump pully off a 302 Mustang...
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By slumlord444 - 9 Years Ago
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Thanks. Thought I was right but better to double check than to be wrong. Wrote it down and lost the note.
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By Canadian Hot Rodder - 9 Years Ago
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GREENBIRD56 (3/5/2015)
1/8 inch diameter - that will do just fine - the brass 3/8 pipe plug will then screw into the short 5/8 hose coming out of the t-stat housing. Simply changes the amount of water that bypasses the radiator and recirculates "hot". Works on any of the engines - not just the T-birds.
Hmm this sounds interesting and I may try this when I put my new motor in since I will be generating a lot more heat with my higher compression. My only concern, is a 1/8 hole large enough as to not dead head the water pump until the thermostat opens?
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By Ted - 9 Years Ago
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Canadian Hot Rodder (3/6/2015)
.....My only concern, is a 1/8 hole large enough as to not dead head the water pump until the thermostat opens?
Dead heading is not much of an issue due to the centrifugal nature of the pump but some degree of hole in the bypass is needed simply to bleed the air from the top of the timing cover housing before the coolant flow goes back down to enter the block. I’d be happier with a 3/16” or 1/4" hole size just to insure a piece of debris doesn’t clog the smaller sized hole.
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By charliemccraney - 9 Years Ago
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I don't think you'll have a problem, Rob. I think the restrictor is accompanied by a few extra holes in the thermostat, so a little coolant is flowing through the radiator right off the bat. These modifications make it take longer to get up to temp, which may not be favorable in your cooler climate.
I've been observing pulleys recently and the Y Block cars tend to have quite large diameter pulleys. More modern cars tend to have smaller pulleys. Y Block trucks have smaller pulleys, similar to those of modern cars. Larger pulley = less pump rpm = less coolant flow at idle and less airflow at idle since the fan is attached. My temp does creep up in summer, if I get caught in traffic.
I'm running a car pump and pulley, which is about 7 1/4" dia and that works out to about 10% underdrive for the pump. I'm working on a project now that requires new pulleys so I will make the crank to pump ratio 1:1 to speed up the pump and fan and we'll see this summer what that does. When I race, I set the idle speed at 1000rpm and I don't notice that issue at that rpm, so it does suggest that the pump is simply turning too slowly at my normal idle speed. No restrictor, yet.
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By 2721955meteor - 9 Years Ago
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my opinion is leave the bypass alone,refer to the post of the 55bird that found haveing all the original shrouding and a new rad or recored cured heating isues in hot weather conditions.to have heads survive you need circulation when stat closed, when you have hot spots you have steam ,when you have steam the temp guage does not register. nothing wrong with a slightley smaler pulley,but with smaller pulley and restricted bypass you will most likeley get cavitation,which is airiated watter which is cracked heads . or fresh engine scored piston ,blowen head gasket. modern engines have water punps with better impellers that work ok with higher speeds.. Ihave rebuilt 2 55 tbirds over several years,1st 1 was powered with a 312and some goodies. recored rad proper shroud,never got hot,even on hot summer days. 2nd one 292 bored to 312 bore,iskey cam no heating isues. my sugestion is service your rad and shrouding,and be aware of modern rad cleanig is poor at best. costic tankes ar not legal hear in bc,rad shops use sonic meathed which is ng. recor is the best .
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By Rusty_S85 - 9 Years Ago
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I personally wouldn't recommend restricting the bypass tube. That is just asking for trouble as that is what allows water to circulate through the block till the thermostat opens. Now if you have a heater that does not have some form of hot water valve either manual or vacuum then you could block off the bypass completely and not have a problem as the heater core is operating as the bypass to keep water circulating in the block.
When it comes to temperatures air flow is what you want. If you are not pulling enough air through your radiator then you wont do much cooling. Then throw in the fact that not all of these Y-block equipped cars came with fan shrouds you are now having more low rpm cooling issues.
I personally don't think there is a problem with the factory setup long as you are stock. Ive let mine idle at 600 rpm for almost an hour and the temp gauge just would not get past the low side of normal. This is also including the fact that I have a radiator that has four tubes separated from the top tank and a 30+ year old belt that might be allowing some slippage.
I would also recommend if you are going to be making more power or you just want more cooling they sell reproduction radiators that has more cores per inch resulting in better cooling over the oem stock radiator. I would go with one of theses personally but all of them have cooler hook ups in them and mine is air cooled, I am too picky to just plug the fittings, so that is something else to think about if someone is picky like that as well.
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By NoShortcuts - 9 Years Ago
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THANKS for coming in on this, Cliff and Rusty_S85,
A cooling system overheating issue has haunted the '55-'57 'Birds as I recall. I wonder if it is related to the water pump bypass discussion, though.
My recollection of an entry on a thread some time ago was that Ted Eaton made the point that the cast iron spacer used between the 'Bird water pump and the timing chain cover diminishes the ability of the 'Bird water pump to work effectively, particularly in low speed (parade type) vehicle operation.
It seems like there was also a comment that the SS (?) fins added to the 'Bird water pump impeller by CASCO Supply did help the apparent low speed vehicle operating temperature problem. Again, this is IF you were using the 'Bird-only water pump-to-timing chain cover cast iron spacer.
A suggested alternative (IF I remember right, from Ted) for the '55-'57 'Bird was to eliminate the water pump to timing chain cover cast iron spacer and instead use an appropriate water pump pulley spacer to align the pump pulley with the 'Bird crankshaft damper pulley.
Can someone confirm my recollection?
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By DryLakesRacer - 9 Years Ago
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This my story on the smaller pulley. First, engine is a stock 292 in a 1956 Victoria. Bought the car with less than 50 miles on total frame off restoration Engine and auto trans included. It ran hot when idling in traffic from the start. Stock 160 thermostat and 6 blade fan. Tune was on specs. Radiator was first even thou it appeared new. Went to 4 core, just took longer to get hot. Added bypass with 1/8" hole, same result. Added Chrysler high flow thermostat, same result. Sealed slot in front of radiator at the top of the framing forcing/sucking all air thru radiator by the fan. First thing that actually helped but waiting at a long signal temp went up. Soon after found the stock seal over the radiator and framing heat up got slightly better. Always had to put the trans in nuetral as raise idle while waiting at signals
Started the engine one day with rad cap off. Ran until I knew the thermostat was open. Saw little to no water movement in the radiator. Raised idle and there was movement. Light bulb went on-----speed up the pump like Greenbird said on this site and I read. Bought a 5+" Mustang pulley and shorter belt and the problem was gone. After thermostat open, plenty of water movement at idle My car is a cruser mostly in town and on the freeways of SoCal I drive no more than 65. That's 10 mph over the limit when the car was new. Thinking of putting back the standard flow thermostat maybe even going to a 180*.
That's it and what worked for me. The dual quads changed nothing but the cool factor and a little mpg. A/C is next and I have no fear of heating up with it......Good Luck
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By GREENBIRD56 - 9 Years Ago
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On a Thunderbird there are two primary design problems - the 1 inch open spacer behind the pump removes any chance of the impeller being efficient - and the radiator is much smaller than a passenger car of the same year. You can also hurt yourself by fitting a thermostat with too small of a passage (restricting the already poor flow) and allowing a poorly operating distributor to retard the spark. You get all or a combination of these in effect - the birds overheat, especially at idle. The bypass - being a "rapid warm up" feature, doesn't help a Thunderbird - especially when it just keeps on warming it up as the day goes by......
I think Ted's advice about removing the one inch spacer - especially if you aren't demanding a "perfect restoration" - is good approach to the efficiency situation. In a standard block (with no spacer), the design of the impeller is still so crude as to prevent any chance of "cavitation" until reaching some astronomical RPM - and certainly not the way we drive our street cars. Fitting the engine with a smaller pulley - like the 289/302 part - had a very favorable immediate effect.
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By NoShortcuts - 9 Years Ago
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Steve: THANKS for pinpointing the early 'Birds' two cooling system design shortcomings, identifying how the cooling system's cooling problem can be exacerbated by the flow restriction posed by some replacement thermostats, and drawing attention to how a malfunctioning distributor's ignition advance curve can potentially result in retarded ignition timing and subsequent engine overheating.
THANKS, too, for reviewing the merits of Ted's suggestion of eliminating the one inch water pump spacer from the 'Bird timing chain cover for those of us that are not dedicated to 'originality' in assembling our 'Bird engines, for your suggestions of using a restriction in the water pump bypass hose, and a different diameter water pump pulley which in conjunction with a more efficient radiator will likely resolve the potential cooling system issues most 'Bird engines can experience in street or highway use.
Regards,
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By 2721955meteor - 9 Years Ago
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re green birds talk of wp cavitation. ony time a waterpump can not move water ther is cavitation. in my case both birds had the spacer between the pump and front cover,tho i agree the spacer cuts punp eficencey some what but as long as the by pass is as desighened it woud be ok ,but more prone to cavitate if rad not adequet.remember 220 with a 15psi cap is not harmfull .lastly my examples wher std trans
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By NoShortcuts - 9 Years Ago
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DryLakesRacer: Kudos for your informative recounting of the steps you took to resolve the overheating issue you were experiencing with your 292 '56 Vic. What you have related is like a case study. Those who read your road-map-of-efforts-taken have a guide that will likely reduce the time, effort, frustration, and expense they have to expend in trouble shooting their overheating issue.
What you have done in submitting your entry to this thread is emblematic of how helpful one Forum participant can be to others who have a y-block technical problem. Thanks to you and all our other members who make the time to relate their hands-on experiences of what they did and how they did it. 
Regards,
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By slumlord444 - 9 Years Ago
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The 1" spacer on the T-Bird is a long known issue. There has been a stainless steel baffle available from the T-Bird parts people for years to fix that problem. I installed one years ago and noticed no difference. Installed a new Ford radiator years back when they still had them and noticed no difference. Going with the bypass restrictor, 6 blade fan, and an electric fan in front of the radiator on a manual switch. If this does not work may try a smaller pulley. On the T-Bird the low hood is also part of the problem. Simple high school physics. A smaller space is easier to heat than a larger space. Problem is we don't want more heat in the engine compartment. Car has always been fine on the highway and tended to heat up in traffic ever since I bought it in '65. A work in progress.
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By Canadian Hot Rodder - 9 Years Ago
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Interesting comments by all! it appears the the running hot issue is primarily with the T-Birds? I never had a problem with running hot, only changed my stock rad to aluminum one because the original brass tank was becoming annealed and prone to cracking from expansion. I run an electric fan on a 190 deg F switch. It would only ever come on if I got stuck in traffic for long periods of time or when I shut the car down.
This being said, I may be perfectly fine, even with the higher compression in my new motor? I will say that if it does tend to run hot, I like the idea of going to the smaller Mustang pulley over the bypass restriction! Can anyone specify what year Mustang / size of pulley would be a good fit?
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By aussiebill - 9 Years Ago
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DryLakesRacer (3/6/2015)
This my story on the smaller pulley. First, engine is a stock 292 in a 1956 Victoria. Bought the car with less than 50 miles on total frame off restoration Engine and auto trans included. It ran hot when idling in traffic from the start. Stock 160 thermostat and 6 blade fan. Tune was on specs. Radiator was first even thou it appeared new. Went to 4 core, just took longer to get hot. Added bypass with 1/8" hole, same result. Added Chrysler high flow thermostat, same result. Sealed slot in front of radiator at the top of the framing forcing/sucking all air thru radiator by the fan. First thing that actually helped but waiting at a long signal temp went up. Soon after found the stock seal over the radiator and framing heat up got slightly better. Always had to put the trans in nuetral as raise idle while waiting at signals Started the engine one day with rad cap off. Ran until I knew the thermostat was open. Saw little to no water movement in the radiator. Raised idle and there was movement. Light bulb went on-----speed up the pump like Greenbird said on this site and I read. Bought a 5+" Mustang pulley and shorter belt and the problem was gone. After thermostat open, plenty of water movement at idle My car is a cruser mostly in town and on the freeways of SoCal I drive no more than 65. That's 10 mph over the limit when the car was new. Thinking of putting back the standard flow thermostat maybe even going to a 180*. That's it and what worked for me. The dual quads changed nothing but the cool factor and a little mpg. A/C is next and I have no fear of heating up with it......Good Luck
All i can add is and not y block for a change, is when i ran 351 cleveland in 72 ford here at tthe drags and with no fan but a reduced diameter water pump pulley and never ! ran hot or got hot. Works for me.
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By GREENBIRD56 - 9 Years Ago
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Rob - On a T-bird there is some forward room to work with, so I put on a Hayden fan clutch - and they show a 10% loss in speed - so a "speed up" pulley is a good idea. I also used a '69 Pontiac 7 blade aluminum fan matched to the T-bird shroud - so you can see "originality" wasn't my goal. In looking for a foxy aluminum pulley to drive all of that shiny stuff, I found CVF Racing ........ and they had a selection of pulleys, four bolt mount - for small block Fords. Call them about mounting dimensions and centerlines - on mine, I bought a two groove and cut one off to net the "right" position. Not the cheap way to go - but made a nice looking custom installation that looks (and is) properly engineered. Photos are in my album over on the HAMB.
Getting rid of the inherent underhood heat of the 'Birds is a pain - and I'm running the iron exhaust manifolds - so I had them "JetHot" coated and that was very effective. Your sedan may need to have the headers wrapped. I have also sealed my carb to the hoodscoop with an air pan so the engine runs on outside air. None of this stuff looks (or works) like a factory 'Bird.
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By DryLakesRacer - 9 Years Ago
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Canadian.. My smaller pulley is a Transdapt chrome single belt for a 56/66 Mustang 289. It is 5 7/8" diameter. I painted it black. Transdapt and Spectre list them with 1, 2 or 3 belts. For some reason the single is listed at 6.125 diameter which probably would have been better. Suprise to me that the 2 belt is smaller than the 1 and the 3 is smaller than the 2.
Remember to buy a shim kit also, add until the pulley lines up with crank pulley. With the radiator out you could probably adjust the snout with a puller. I believe the belt was 1" shorter. Good Luck
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By charliemccraney - 9 Years Ago
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CVF racing have pulley specs online. The bolt pattern and pilot diameter is not limited to Ford, so you have lots of options.
http://www.cvfracing.com/
Something to keep in mind is how the pulley diameter affects the pump. Everything else the same, smaller pulley = higher pump rpm and larger pulley = lower pump rpm. I've only found one article about pump rpm and it is indicated that 7000rpm is a max for racing and for the street, you want it at least turning as fast as the crank. Source: http://stewartcomponents.com/index.php?route=information/information&information_id=8. With that in mind, for racing the smallest water pump pulley you want with the stock damper pulley, which is about 6 5/8" is about:
5.3" for a 5500rpm shift
5.7" for 6000rpm
6.2" for 6500
Formula, (shift rpm x crank pulley diameter) / 7000
Another thing to consider is with a smaller pulley, and therefore higher pump rpm, more power is required to turn the pump so you don't necessarily want to pick the smallest pulley.
So for street / strip, you want something no bigger than the crank pulley but no smaller than that required for your expected shift point to keep pump rpm below 7000.
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