I'd say there's a major defect in that carb. Ring Holley's tech men and they'll should walk you through the diagosis to see if the problem lies with them or not.

 

carb

Where do you have the floats set at???

What fuel pressure????

Is the carb the "ONLY" thing you changed?????

Have you done anything yet to fix it????

Keith

 

I bought a new holley street avenger 670cfm. And put it on and the car would not go above 2,000 rpm without cutting out and back firing. But below 2,000 it ran great and idled prefectly. Just curious if anyone else has had this problem are might give me some ideas on what to look at.

Was it backfiring through the carburetor or the exhaust (after fire). Normally if you have a backfire through the carburetor, it is an indication of being too lean. An afterfire (backfire out of the exhaust) is normally an indication of being too rich. This can be caused from the carburetor being out of tune, or the ignition system not being set up properly.

 

Well i was running a 750DP and it ran fine i swapped to the avenger and all hell broke loose. It was backfiring out the exhaust. As for where everything is set it was put on straight out of the box no tuning. I thought carbs were supposed to remotely close to running ok out of the box.

 

carb

Well sometimes you can just bolt them on ,but most of the time they will need some tuning. I just put a avenger on a customers car and it started right up and idled close.... But the front float was about 1/2 turn to high, and the idle screws needed some adjusting.....

You really need to check the float levels.....

Are you running a vacuum advance on the distributor.....

Keith

 

Yes my distributor has a vacuum advance.

 

carb

Any chance you have the hose hooked to the ported vacuum on this carb and it might have been on the manifold vacuum on the other carb...

just for the fun of it put your timing light on it and tell us what initial and total timing you have...

Keith

 

I have the same carb I haven't any problems with it. Take your vacuum advance off going to the distributor. That's what I had to do. It was advancing it to much.

 

ive got a 770 on my 454 & after normal adjustments it ran fine. Ive since put in a larger booster, but thats it.

 

I also have had 2 570 Avengers on 2 305s that I put together, both ran great

 

The Avengers are no different than any other Holley carb. There is no magic making them somehow bolt on and go as they would like you to believe.

Avenger =
Powevalve blowout protection-A drill bit and check valve kit worth $1.00, maybe.

Secondary metering block

Quick change secondary spring kit-$20

Shiny finish

 

Well i had put the carb on a couple of months ago on my old motor and thats when it ran ruff. Now i have a new motor and just got it started today and it was running the same as it did before. So tommorow im going to check the float level and see how everything sits. Im going to try and do some tuning and see what happens.

 

carb

I think with some tuning you are going to get it straightened out...

Keith