Engine hesitation under lite acceleration
Thread Starter
6th Gear
Joined: Jun 2009
Posts: 6
Likes: 0
From: Stillwater Ok
Engine hesitation under lite acceleration
I have a 78 Vette with a 74 454 block with 69 427 vette heads and intake, a mild cam and a holley 750 dual line double pumper. It has the black acc pump cams in it now. Under hard acceleration it runs like a raped ape. But if I am doing say 40 mph and the speed limit jumps to 50 and I accelerate to pick up speed, I get a split second hesitation and then it runs fine (no back fire). I have adjusted the carb repeatedly, set the timing, looked for vacuum leaks. The plugs, wires, dist cap and rotor are fairly new. I had a 68 GTO with a Hi po 69 428 pontiac and it done the same thing. On the Gto I changed carbs, distributor, wires, plugs, dist cap and rotor, Even tried several different centrifical weights and springs in the distributor. and nothing helped.
What could it be?
What could it be?
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
Make absolutely sure you have no vacuum leaks. All rubber hose connections are fresh, especially ones with no clamps. What do your plugs look like ? What's your jetting ? I assume you have also read the threads on problems with Holley street avengers and addressed any issues with the accel pump lever and contact points ? I chased the exact same problem for a while and it turned out to be a combo of several very small vacuum leaks and lean jetting.....
Pro
Joined: Jul 2010
Posts: 691
Likes: 25
From: Boynton Beach Florida
You can either try some different acc pump cams or install a larger discharge nozzle (squirter) the nozzle is the most common and easy remedy. Sounds like you just need a slightly great shot of fuel
