Stumble @ Cruise

DeeVeeEight

Fast Pedalphile
Joined
Nov 3, 2008
Messages
2,265
Location
Southern New Jersey, USA
I have a fresh 355 with a mild build (355 hp, 390 tq.) roller cam, 9 to 1 compression, air gap intake manifold topped with a Holley 4150. Vacuum is at 16 inches, idle @ 750 rpm. Idle is great and the engine runs strong and smooth.
When cruising on the highway, if I accelerate lightly there is a bit of a stumble. I have been doing a bunch of internet reading but this is where I come for the answers I trust. I am leaning towards the primary jets being too lean. At first I found that the accelerator pump was out of adjustment and I have that back within specs (as far as I can tell) and it has helped a lot - but the stumble, though less noticeable is still there. Your thoughts as always, are appreciated.
 

69427

The Artist formerly known as Turbo84
Joined
Mar 30, 2008
Messages
2,943
Location
Clinging to my guns and religion in KCMO.
I agree with the previous post about first checking the operation of the accelerator pump.

Also, do you have the appropriate accelerator pump cam for your carb/manifold combination? A pump cam swap a few years ago cured the tip-in stumble on my engine.

My $.02
 
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