bikerbilly18

The engine stumbled with a holly double pumper and quadrajet. Tried both rich and lean . Air/fuel ratio from 12.5-15 confirmed with gauge. The engine did the same thing when installed on another vet with another transmission before I replaced it with a crate engine. So I'm confident its not the carb that's causing it. Seems to happen around 2000 rpm regardless of engine temp. I feel acceleration drop and very quiet poping. Checked and double checked timing. Tried advancing and retarding. Ordered a new distributer and will have it in the next week.
Am I on the right track assuming spark issue? Or is there anything else I should look into?

If it helps:
Cam is mild
World torquer rt heads
Has decent vacume 15hg or so at idle.
Starts and idles well.
If I rev in park the stumble does not occur.

gungatim

time to put it on a scope and dig into the ignition system. miss/popping/detonation under load?

what do the plugs look like?

bikerbilly18

Replaced plugs during engine swap.

Jebbysan

Do a leakdown....you may have a small valve leak.....or a slight intake leak.....
Do you have a steady vacuum needle at idle?
Was the distributor the same in both cars?

Jebby

bikerbilly18

Yea same distributor when used on both cars. Vacuum is steady at idle.. And if I put my hand over oil filler hole on valve cover there is no pulsing on either side. Took it for another test today and confirmed issue does not occur when auto trans is in park. And stumbling only occurs if I press gas pedal down at least 75%

bikerbilly18

ok solved issue when i reinstalled on current car i crossed 5 and 7 plug wires. now im just hoping the similar issue when i bought it installed in the other vet was the same thing or the faulty pressure regulator making the holly go super lean. Preying other transmission isn't shot!