Elvis runs, but when the engine's cold it only wants to idle. Giving it just a little gas very slowly causes it to quit. Doesn't seem to like much choke after 10 seconds of idling. Problem gradually gets better until when the engine is fully warmed up, it runs up the rpms better, but with still a hesitation when you start to put the pedal down slowly - stumbles, then catches up.

Tried changing the timing and dwell slightly, doesn't help. Turned in the idle screws to snug then back them out 1.25 turns, doesn't help.

Did the timing per the book (right at the mark for #1 with the vacuum advance disconnected. Advances about 0.75 inches when you run up the rpms (wish the pulley was marked in degrees). Idling at about 450 rpm. Dwell at about 25 degrees.

Feels like it's running too rich, but I've done the idle screws 3 times and turned them in slowly until it starts to stumble and then backed off a quarter turn which put me back at about one full turn plus, close to the 1.25 turns I started with.

This is a Merc 254 if that matters, Holley 94 two barrel, stock exhaust, stock everything so far as I know except converted to 12 volt. Got the plugs that Advance Auto cross referenced but don't remember the number, sorry.

Weak ignition? Tried it with and without the ballast resistor.

Just remembered, I had a bunch of backfires from screwed up plug wires when starting it the first time and probably ruined the power valve. Could that be it?

BTW, if you spray in too much ether or drip in too much gas with an engine that isn't starting then you can get a "backfire" in the muffler that will peel it open so the outside wrapper of the muffler is almost flat. Don't ask me how I know. When it happened, my 17 y.o. son took off faster than I've ever seen him move before. Sounded like 10 M-80's going off at once. The toasted muffler is now hanging like a deer head on the wall of the garage.

Advice?

-Scott

'53 F100 Elvis

 

Sounds like typical carb problems. There are really fine idle circuits in the carb body and if plugged they won't run worth anything.

I had similar troubles when I got my 48 running. I solved my problem by picking up an unknown carb at a swap meet. Slapped it in place when I got home and stood there amazed as the darn truck ran perfect.

Backyard mech trick you might try. With the air cleaner off, bring the rpms up to about 1500 and slap your hand or something non-flamable on top of the carb. You don't need to stall it, just bog it down good. Same effect as pulling the choke all the way out. Repeat as necessary....occasionally you can flood the circuits and flush the crap out that way. Only alternative is to totally dismantle the carb and clean it all out - like the carb shops do.

Never, ever run an old engine without an inline fuel filter. The screen in the fuel bowl only strains out birds and tennis shoes. Anything smaller goes into the carb circuits. (ok, maybe I exaggerated a bit)

 

I don't think you exaggerated at all!!

Yes, I've had good luck with the "revving the engine and then choking it" method in the past. I've typically started at a higher rpm (2000-2500) and then either slammed the choke plate shut or held my hand or a rag over the top of the carb until its almost dead and then let it clear out and see how it runs.
You better open the garage door when you do this or your going to choke yourself out. More than likely, you will need to pull the carb apart and clean it up.

Good luck
Bobby

 

I had the same trouble with my 51 F1. "burped" the carb a few times and it cleared right up. Good luck and let us know. Tim

 

Which hole is your accelerator pump rod in?

 

Is your manifold heat valve working properly, also you could try hooking the accel pump setting on the longest stroke.

 

i had some trouble with my 49, there is play in the excelerator pump linkage. the butterfly will move some before pump rod doe's.so i had to choke it some to tightin it up then push it back in when i got going. check your linkage on carb and tightin it up if play . took care of mine.

 

What's a manifold heat valve?

-Scott

 

Sorry I miss read you post, I thought it was a Flathead 6 cylinder. Your 8 uses the internal exhaust port to heat the intake.