Stumped and Frustrated with a Holley 670 Hesitation

70408dart said
Dont know if this will help or not but here is what I went through with my 770 Street Avenger. I bought mine used so I knew nothing about it. Put it on my 360 and it wouldnt run for crap. bought a rebuild kit for it and proceeded to take it apart only to find out the coating on the inside of the fuel bowls was literally peeling off in chuncks. Called Holley to try and order some parts only to find out Holley wanted that carb back and they sent me a brand new one. This probably wont help you but it might be worth taking a look at your fuel bowls. Food for thought.

Wow! your not the only one I have heard of this happening to. I doubt I could be that lucky.

OldmanRick said
From what I've read so far, this is not a secondary problem. You're either going lean in the primary or your timing/ignition is acting up at the hit/load. That #31 nozzle should be plenty, so I have to wonder if you're running a vac advance hooked to the manifold vacuum? Even being a little lean on primary jetting shouldn't cause it to dump at low speed full throttle? Is the primary float level consistent?

Anything else you can think of may help. Either the carb is bad, or we're just missing something? I'll keep thinking on it...

Trailbeast mentioned I should eliminate my HEI being the issue by hooking up 12v from the battery to my coil and taking it for a drive. Basically saying that if the problem still persists then we can assume that its not a voltage drop at the peak load time.

So even though the problem got worse when I removed the spacer your still leaning towards the possiblility of being lean on the primarys? I do have bigger jets, but they are 4 sizes bigger than the stock ones.

My vac, advance is hooked to ported vacuum, not the manifold vacuum.

I've checked my floats a couple times, but never with the car running. I didn't feel like I wanted fuel dumping on the manifold. I had the fuel set just so it was weaping out of the hole, (basically level with the bottom of the hole). I can double check that again.

I honestly cant think of anything else. However I can double check my timing and get back to you all with those numbers.