Tach RPM bounces around and engine stalls

[saludora]

Fresh 440 motor with solid roller ect. Got engine started and timed idle d and ran great. Warmed,it up took for test drive ran fine. Stopped at parts store and upon restart hard start once,started at idle RPM on tach bounced around and engine stalls. Driving it home was able to start with heavy throttle but when driving home slowed to go around corner and engine stalled. So bad gas, power valve, coroded distributor? Vehicle sat all summer,in garage. Any help would be great to start trouble shooting

 

[oldbee]

Bad gas is my first guess. Plugged passage/s in carb.

 

[moparwacko]

Didn't mention what carb setup, I've had trouble with Holley's after sitting - are you running ethanol free gas??? Eats up a sitting carb if it was never upgraded to newer type gaskets/power valve/accelerator pump. Running a Mopar elec ignition?, clue to a bad control control will be erratic ignition symptoms like you mentioned.(tach jumping) Check grounds really good, I run another ground wire from control case to engine ground on firewall after chasing gremlins like this many times. You could also throw a cheapie NAPA box on just to see (I keep one as a spare), before you go tearing into carb.

 

[saludora]

6 pack carbs, all ways 92 octane non ethanol. Msd 6al2 and billet distributor

 

[saludora]

I was thinking dropping a bottle of heat and octane booster in since it sat with half tank all summer

 

[Ranger16]

Is the tach actually responding to the engine RPM? Mine did that on and off for a year. Every time I thought I solved it, it eventually returned. In my case it was electrical and I think maybe several gremlins. One was a corroded connection on the starter relay battery cable. The final one was loose ammeter posts. I bypassed the ammeter and is has been rock solid ever since.

 

[saludora]

It does it them the engine stalls. Maby a bad fuel issue

 

[saludora]

Added heat treatment and octane booster and 5 gallons of 92 non ethanol fuel and so far idles and runs fine... Fingers crossed when I take test drive tomorrow