Hot Rods help needed on a 55 desoto hemi

I joined yesterday and posted under "introduce myself," but am hoping to get more views in this discussion.

I purchased a finished 32 ford 5 window that has a 291 desoto hemi. it has 4 strombergs. runs on the center 2 and i disconnected the progressive linkage to the outer 2. it backfired through the carbs when over half throttle. ignition timing is set at 35 btdc. if i adjust to 10 it works worse. it has 35 deg of dwell and goes to 60 when it bogs down and backfires. the timing advances properly about 22 degrees during acceleration. it has a solid state pickup and mechanical advance. i cant find a control module. any ideas?

 

Sounds like it's leaning out, you didnt say if it ran fine before you disabled the outer carbs. I'd retrace my steps and reset it as it was when it ran fine, the carbs may be tuned to run with 4 and loosing the end ones resulted in a different AFR.

 

See above. I don't think you can do that. You now have 4 way lean cylinders, it sounds like.

 

rich, the manifold runs on the center 2 carbs and the outer carbs come in as adjusted by throttle stop. all 8 cylinders are running rich(plugs black). nick, i am trying to remedy the issue as i received it. it is a 35 5 window coupe built by someone, sold to someone else who never drove it who sold it to a dealer where i bought it as it is. his mechanic could not het the carbs adjusted any better than they are and had decided that it needed a distributor. knowing what i know, the distributor appears to be working correctly. and the engine just seems to drown on fuel

 

Ok, that's a bit more info. I also didn't see the model of carbs you're running, but I'm gonna guess and say they are Holley 94's/Chandler-Groves. If that's the case you could have any number of issues with them; Jetted too high, blown out/leaking enrichment valves, incorrect style enrichment valves (they come in modern rebuild kits and will screw in, but they are wrong for the older Holley carbs), enrichment valves with wrong vacuum signal rating, too much fuel pressure, stuck needle valve, gouged needle seat...you get the idea. Same idea with Stromberg 97's, minus the enrichment valve issues, they tend to be over jetted for multi carb setups.

If your distributor vacuum advance is hooked up to a full manifold source as it should be, that needs to be disconnected when making timing adjustments.

 

Is your intake a staggered four? Or inline? Or a log? Is it a 180 degree intake or 360? Engines that are backfiring though the carbs, in my experience, are lean. Way lean. If you are running 94s, the power valves can be a real challenge. I gave up and plugged them. But that is the wrong thing to do. If your plugs are wet, it can be because that cylinder is not firing. Have fun, good luck.

 

i believe they are stromberg 97 but markings on the side say sp-10. I will add a couple photos. 3.5 psi of fuel pressure. no vacuum advance, mechanical.

 

Yes those are Strombergs. I'd be getting a regulator to bring the fuel PSI down to 2, that's literally all that they need.

 

it has an inline regulator, i will try 2psi and see how it goes. thank so much

 

i adjusted it to 2 psi, better throttle response and went over 2400 rpm, i will have to redo the timing and see if it cured it completely. specs say 10 deg btdc and 35 deg dwell is that correct?

 

Hemis don't need a lot of advance I'd go for 30 degrees total.

 

Your carbs are not real Strombergs. They are Speedway repops. That might be part of your problem. Do some research and you will find that some people have had problems with them. You might want to look into getting some new ones from the real Stromberg company that are set up for your engine.

 

Those fuel lines are scary, get a 5 lb fire extinguisher

 

OK, I don't want to hijack this informative thread, but could you post a photo of your car showing the engine mounting in it? I have a DeSoto hemi that I was considering putting in a 32 Ford and I would like to see how well one fits in there.

 

Seriously, that fuel delivery system looks mondo temporary.
Nice lookin motor though.
It sounds like you have the problem on the run.

 

Totally agree. Those fuel lines are a fire just awaiting an opportunity, which you provide when you put fuel in the fuel tank.

Don't know about the cheap look-a-like carbs. If those were real, Stromberg designed and sold the model EE-1 (the Ford version was stamped "97") to operate at 3 1/2 psi.

Don't know about running on only the center two, would need to have the carbs off, and inspect the manifold design. I would suggest running on all 4 simultaneously. They will need synchronization.

Nice looking engine, except for the fire hazard fuel lines.

Jon

 

I know it an old post but I would try to set them at 1.5psi or the old Strombergs like to flood like crasy!!!
Just my 2 cents..