|
By customline3859 - 2 Years Ago
|
|
Good morning all. I've been working on a 292 with a 3x2 intake for several years now. I've gotten to a point where I can drive the vehicle for short trips, but I'm intermittently getting a backfire under acceleration once the engine warms up. Its also cut off on me twice at a stop. I think it might have been vapor lock, because it restarted pretty quickly. Ive sent the carbs out to be professionally rebuilt. I called the cam manufacturer and my initial timing is where it should be. (10⁰ btdc) I've been trying to do some research about what else might be causing my concern. I'm wondering if I'm getting an issue from the heat riser ports running under my center carb. I'm using the wide open gaskets, not the truck ones with the smaller opening. Could this be my issue? I'm trying to make the power tour this year and I'm running out of time. Any help would be appreciated. Cam is an isky 301333, Weiand intake. 292 bored .090 over. Red's headers that have been ceramic coated to lower under hood temps, gasket-match porting on a set of G heads.
|
|
By Joe-JDC - 2 Years Ago
|
Have you jetted up for the ethanol in the fuel? I would install a 1/4" phenolic spacer under each carb, remove the metal from the intake gasket heat riser hole, block the heat riser with a thin piece of metal, and set the initial timing at 12-14* and try it again. You can get the spacers from Speedway in various thicknesses. Backfiring is typically caused by lean mixture of fuel. Joe-JDC
|
|
By customline3859 - 2 Years Ago
|
I have not touched the jetting at all. I sent them away to Charlie Price at Vintage speed. Like I said, there is no metal in these intake gaskets at all. Ive set up an air fuel gauge with an oxygen sensor to monitor the mixture. Its at about 13.5 to 1 at idle. I am intentionally leaving it rich to avoid the lean condition. I have hard lines bent for my fuel already. If I have to go back and make those again due to a spacer, I'll pull the entire set up off and sell it.
|
|
By Robs36Ford - 2 Years Ago
|
2 other causes of misfire/backfire is a leak in the intake gasket or leak somewhere in the exhaust most likely closer to the header.
|
|
By Joe-JDC - 2 Years Ago
|
The first thing I would do after seeing your setup is to wrap the copper lines is to insulate them with a wrap or rubber hose to keep the heat from radiating on them and causing vapor lock. Copper is an excellent heat sink, and that may solve your problem. I cut 3/8" fuel hose to length, and split it to slide over the metal fuel lines. Works just fine.  Joe-JDC
|
|
By customline3859 - 2 Years Ago
|
|
Interesting. I'll try that out. I'll keep everyone posted on that. Of course it's raining today, so I won't know today. I'm also trying to sort out an aod kickdown cable, but that's an issue for another day.
|
|
By customline3859 - 2 Years Ago
|
|
Still backfired on me a few times while accelerating. I don't have a way to get the actual temp, but all the linkages in that area are hot to the touch. Engine also stalled out on me at a stop. Transmission shifted sporadically even though I made no adjustments to the kickdown linkage.
|
|
By Daniel Jessup - 2 Years Ago
|
Joe is hitting the right angle I think... check out this post on my blog concerning ethanol in the fuel and what it can do in high temp situations. The boiling point of gasoline is very low when ethanol is included in the mix...
https://www.hotrodreverend.com/post/2019/07/13/1955-ford-part-81-running-with-the-devil
|
|
By Joe-JDC - 2 Years Ago
|
|
13.5 is not rich enough with the ethanol fuel in my opinion. I would feel safer with 12.65-12.85 at idle and under acceleration. Float levels may be off even though you got the carbs rebuilt due to shipping and handling. I still think you need a phenolic spacer, and 1/4" should be able to be fitted under the base of the carbs with the fuel line block moved up to match. The lines could stay the same. Joe-JDC
|
|
By Ted - 2 Years Ago
|
Ditto on the comments about ethanol laden fuel running leaner. I typically have to add a couple of jet numbers to the jetting to compensate for 5-10% ethanol fuel.
I have had a couple of Ford Y 3X2 setups recently in the shop with the Ford/Holley 2V carbs that had been ‘professionally’ set up elsewhere. Both setups initially ran extremely lean when dyno testing them as delivered. Upon disassembling the carbs, I found that the end carburetor power valves had been removed but the end carb jetting had also been further reduced from the stock numbers. On both of those 3X2 set ups, the primary jetting was #55 and the secondary (end carbs) was #53. In the grand scheme of things, when blocking the power valves, jetting should be increased, not decreased.
On the last one I ran, I bumped the jetting up to 59P and 60S and immediately saw a plus thirty horsepower improvement along with the lean popping during load being reduced so I knew I was on the right track. I ended up with 59P and 67S jetting and the engine both idled and throttled up well. This particular engine had an Isky E4 camshaft so nothing wild in that department.
|
|
By Richard - 2 Years Ago
|
Vintage speed has adjustable main jets $39.99 a pair
i did not see any larger main jet then 60
|
|
By customline3859 - 2 Years Ago
|
|
I'll go ahead and order the spacers. I'm going to pick up a infrared thermometer to get a reading on the temps around the fuel lines. I try to use non ethanol fuel when I can, but I won't be able to guarantee that I can find it on long trips. I'll check the jets, but I want to say they're something like 51s and 48s. Does anyone have any dealings with Charlie Price?
|
|
By customline3859 - 2 Years Ago
|
|
Also, could I expect to need similar sized jets? I'm in NC, so we're basically at sea level.
|
|
By Ted - 2 Years Ago
|
|
Richard (4/2/2023)
Vintage speed has adjustable main jets $39.99 a pair.
I did not see any larger main jet then 60.
While it has not been clarified exactly what carburetors are being used, the Ford/Holley 3 bolt 2V carbs do use the conventional Holley jets which are available in most sizes up to ‘100’ through many different parts suppliers including Speedway, Jegs, and Summit. The Stromberg carbs on the other hand use main jets that are specific to the Stromberg carbs and slightly more difficult to find when looking for specific sizes.
|
|
By Hoosier Hurricane - 2 Years Ago
|
|
This is an afterthought, but would this Weiand manifold happen to be made for the '54 239 and 256 engines? If so, intake gasket sealing would be very iffy with G heads. Likely cause vacuum leak.
|
|
By customline3859 - 2 Years Ago
|
|
I will get the part number off of the intake when I get back to the house. The carbs are holley 94s. 1 1/16" venturi on the center and 1" on the secondary carbs
|
|
By customline3859 - 2 Years Ago
|
|
Intake is the Weiand FM 436
|
|
By customline3859 - 2 Years Ago
|
|
Jets were 56P and 50S
|
|
By paul2748 - 2 Years Ago
|
Would it be worthwhile to remove the 3 x 2 manifold and install a 2bbl or a 4bbl manifold just to check things out ? If the 3 x 2 is designed for a 54 engine as stated above.
|
|
By customline3859 - 2 Years Ago
|
|
Before I sent the carburetors away to be rebuilt, I blocked off the outer carb ports on the intake and ran it on the center 2bbl. I did not experience any sort of pop or backfire on acceleration. I don't believe the intake is leaking. I referenced a head to head article that Mr. Eaton posted and the intake I have is listed as a "large port" I have swapped the jets in the carbs to the 59P and 67S. I'm going hunting for the correct fittings for rubber fuel hose tomorrow. Spacers are set to arrive on Friday. I'll put everything back together then and see how it goes.
|
|
By customline3859 - 2 Years Ago
|
Well. I've swapped for rubber hoses. Added the spacers. Adjusted jets to 59P and 67S. Adjusted timing to 12⁰ btdc. Intake temperatures are about 170 ⁰ across all three carbs. Adjusted idle and mixture screws. Same symptoms. The only other thing I can think of is maybe the secondary carbs collar is set too far back, so I'm not activating them when I need to. I don't really know what else to do. 
|
|
By Hoosier Hurricane - 2 Years Ago
|
|
What distributor are you running? In an early post with a picture of your engine, the distributor is not visible, but the firewall is '55 or '56. Are you running a '55 or '56 all vacuum advance distributor. In your last post, you wondered if the secondaries are coming in too late. How soon do the open. Maybe they come open to soon and do not have enough air flow to start the fuel flow. Do you have accelerator pumps in the end carbs?
|
|
By customline3859 - 2 Years Ago
|
|
I have the later style distributor. I believe it's a 1960. Outer carbs have plugs in them. No power valves.
|
|
By Dave V - 2 Years Ago
|
|
Are you by chance using a Pertronix ignition in that distributor. They can give you these kind of problems
|
|
By customline3859 - 2 Years Ago
|
|
I am using the pertronix ignition. I've read that when the pertronix fails, that it is just completely inop though. I had this distributor in my last 292 2bbl and I didn't have any trouble out of it. It ran ok on this new engine with the outer carbs blocked off as well. Not to say that it couldn't have malfunctioned between then and now though.
|
|
By Ted - 2 Years Ago
|
Are you sure the end carbs are getting fuel and/or the float levels are high enough? This is potentially just one of the end carbs acting up.
Another option is to block the end carb pads and try each of the end carbs individually as a center carb. This might help to isolate a carb that is not doing its job and can be addressed accordingly.
|
|
By customline3859 - 2 Years Ago
|
|
I have not blocked the carbs back off to run on the center carb since getting them back from Vintage Speed. I just wanted to say I appreciate everyone's help with trying to get this diagnosed. I wish you guys weren't so far away. I'm in the process of removing this intake to sell it. The vehicle will make more power with the 4 barrel. The cool factor of the 3x2 doesn't outweigh the amount of hassle this has become. Thank you all for your time.
|
|
By Rudder2fly - 2 Years Ago
|
|
I to have been down this road. After spending $900.00 at Vintage Speed for carbs, $400.00 for Eldbrock 553 3X2 intake, and $ 125.00 progressive linkage countless hours tuning I just said the heck with it. I'm running a Holley Quick Fuel-SL-450 VS Slayer. Runs like a Stripped Ape. The flash under the hood is not worth the trouble.
|
|
By Dave V - 2 Years Ago
|
|
The last Pertronix that failed on me would not allow me to accelerate but would run just fine idling. I kept thinking it was the accelerator pump in the carb. That was a Pertronix II
|
|
By Joe-JDC - 2 Years Ago
|
|
I don't mean to be negative, but a few years ago, there was a forum member with a similar problem, and he sold his unit. I acquired the set-up, and upon tear down, the manifold had a huge dirt dauber clod in one of the ports. It was fuel washed and slick, so it had been run with the mud in the manifold. It was nearly blocking one port, so there was no doubt that it affected the idle and running of the engine. I ported the manifold, pressure washed it, and have run both the 94s and Strombergs on it with great success. Also, one of the adjusting needles had been run in tight, and backed out, breaking off the tip and making that idle circuit inoperative. I know this was supposed to be rebuilt carbs and built by an expert, but there are always little things that bite when you least expect it. BTDT. Joe-JDC
|