Odd problem while driving..

[grassy]

Not sure what to call this problem.

Rebuilt 360, Edelbrock Performance Intake Manifold, Holley 670, new gas pump TTis..

When driving at a constant speed, you can hear the engine going up and down slightly...but not enough to affect the speedo.. but having perfect pitch, this is driving me nutz..

I am guessing that it may be because the gas tank isn't vented..

Should I be looking else ware for the culprit ?

Thanx

[FONT=&quot][/FONT]

 

[qkcuda]

Would you call it surging slightly? I had a similar issue with too much vacuum advance. The easy way to test it is to rev the car slowly in neutral and see if it starts to break down over a certain rpm. When I did that the problem became very apparent on mine. Disconnected the vacuum advance and no more issues. Surging can also be caused by a lean condition.

 

[abodyjoe]

is it lean?

 

[Snake]

well he has the 670 Holley its lean.

 

[grassy]

I thought we are running slightly rich....better a bit rich than lean was our motto when we raced..but not sure at the moment...however, the label surging would be accurate.

I do know I am running slightly advanced at the moment..

Don't I need the vacuum advance ?

Can I correct the lean condition...?

Still learning about this carb..

 

[dragondan64]

Just had that problem on my car and it ended up being the dang accelerator pump, changed it just got back from cruising around and problem solved! So check it for pin holes or cracks also check your air and fuel mixture screws they can cause a bunch of weird stuff, good luck!