318 Stalling Problems HELP!
Hi All,
I've been working to get a brand new long block running. I have gotten everything together and have set initial timing. The engine idles like a dream. It revs hard like a dream. The problem is if I slowly bring it up through the RPM's when in neutral, consistently at 2,000 RPM's its stumbles and stalls. If I immediately let of and let the RPM's fall it almost always stumbles but does not die. If i stay in it it always dies.
I'm at a loss and am looking to you experts here. Any help is much appreciated.
From the description
Your carb should still be on the transfers, maybe at the top, switching to the mains.
When you whack it open in neutral you get on the mains right away with the pumpshot covering the lean hole.
At idle,the mixture screws can compensate for a poor transfer circuit.
Ima guessing this is strictly a transition problem at the top of the transfers, or the bottom of the mains.
Since these circuits are intimately controlled by engine vacuum,so yes,low vacuum that can lead to this problem. But so can a multitude of other things, most of which have already been mentioned.
But here is the stumper
If I immediately let of and let the RPM's fall, it almost always stumbles but does not die.
If it was a transition problem, or it was a shorting point-plate; as soon as you backed off, it would be business as usual.
And the clincher
If I stay in it, it always dies.
In my experience I think only two or three things can cause this;
1) insufficient fuel in the bowl, or
2) a severely restricted exhaust system.
3) a flooding condition.
#3 you wouldda seen and we wouldn't be here,lol
#2 is easy to check; get a helper
#1 leads to a fuel-pump volume output test....... with the engine idling, and the gas-cap cracked open.
If this is adequate, we're back into the carb, checking the pumps ability to keep the bowl full, the wet fuel level,and the manifold vacuum signal............And just maybe, the T-port sync., but not for the usual reason.
Good luck