360 stumbles when going from full idle to full throttle.

I've got a 360 LA that had the same issue. Mine is also a low compr. engine that we shaved the heads drastically and put big valves in and played around with porting them. Its got a thumpr cam and a Holley 750 vac sec. Once warm she idled good and as long as I eased into in then stomped it ran great, but from idle to floored it would stumble. :banghead: My timing is like yours 20 initial 34 all in. Ended up being the accelerator pump shot, I changed the plastic cam on the accelerator for a quicker and larger acc pump shot and fixed it. With the low comp. pistons the 750 is a little big carb. but will work, it does for mine but it takes a little longer for the air velocity going through the carb to get the jets pulling the way they should so you will need a larger pump shot to give the jets time to catch because the velocity through the carb horn is reduce due to the bigger size.:burnout: