I took it for a spin around the block this evening running on just the center carb. Still stumbles above 2500.

  Dennis in Lititz PA

Most engines will free rev better than under power pulls. Just reading here I'm suspicious of your fuel delivery system. Have you change your filters lately? Do you have an electric booster pump on it? Kind of sounds like not enough fuel getting to the carbs. I have to run a booster pump on my 56 with the McCullouch. Anytime I make a hard run, even with a 427 hipo mechanical pump, it would run out of fuel in second. I expect your new engine is demanding more fuel that before. Anyway thats my thoughts. Hope you get it cured soon. If not I bet it can get fixed in Columbus! Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I have just put an rebuild 272 in my 55 F100, with an IskyE-4 cam (installed 3º advanced),large valve G-heads and running one Holley 94.I have used the original pulley from the 239 engine but under first test run I forgot that the timing mark on the pulley don’t mark TDC but 10º advance, so on my first run my initial timing was in fact around 24º advance. Just thinking if the distributor set in its advance it will get much to much advance and probably run very bad! I have tried to run the 239 distributor but that don’t work very well. I have read that the engine vacuum can change quit a lot with the cam, so now I have modified the vacuum port on the Holley and running MSD-8383 distributor. Just my experience with the E-4 cam and timing.

Dennis:

You have changed heads. What valve springs are you using? Is it possible that the valve springs are "soft"? Are they shimmed as required?

John - "The Hoosier Hurricane"

John, I got the police package springs from Schuman. The timing pulley has marks at 0 and 10, my total advance is 26. Is that enough?

A couple of years ago when it was really hot at Columbus, I was running out of fuel at 3/4 track. That felt different. Now all 3 carb bowls would be full for my initial hit of the throttle.

I had gotten valves and springs from Schuman.

  Dennis in Lititz PA

Hi Dennis,

I think most run upwards of 36* total timing and backfiring out the exhaust when you let off is normally a retarded condition. Did you check your timing with No 1 cyl to TDC with the new crank? maybe the relation of No 1 at TDC is slightly different than the 239 crank was and your marks may be off.
Just a thought!

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Just an early morning thought. You mention you replaced the plug wires and cap. You also mentioned it backfires when coasting. Are you sure you have the right wire going to the right plug. Maybe you have two crossed and it doesn't show up until you put a load on it.

Just another 1¢ worth.

"The Master Cylinder"

Enjoying life at the beach in SOCAL

Dennis,

Obviously you thought about this, but backfiring on the "over-run" is ty[pically a lean condition.

Could be intake (underneath) or a dist Vacuum can, or a carb gasket/ internal leak. Have you checked plugs to try to isolate it? Master could right too, a weak spark could possibly act like that.

Frank/Rebop

Bristol, In ( by Elkhart) 

Or the ubiquitous "slipped damper ring" could indicate incorrect initial timing.

Dennis:

Can you stand one more thought from me? I assume you have a hand choke on your center carb, I can't remember for sure. If so, while running on the center carb, pull the choke out a little and see if it helps, at least until it needs more air. That would at least tell you if you are lean.

John - "The Hoosier Hurricane"