Have a 770 street avenger on my 440. Engine has 10.2 comp. Comp XE268H cam, RPM Performer, Headers and 3" duals. Primary jets are 72, and the secondary are 75. Seems like there should be more jetting than this. Fells like the car should go quicker than what it does. 73 Sat auto, with 3.23 rear. Is this average?

Id go at least 74s/80s..

The couple of Street Avengers I have tuned were extremely lean out of the box. Worse in my area with 10% ethanol .
I had a 670 that even the idle circuits were too lean to work well on a mild engine . Basically they need some help.
Keith

I bought this carb from a friend. I don't know if he messed with it at all. I've read other posts where a member had a 360 that was jetted high 70's and mid-upper 80's. That got me thinking that mine sounds way lean. I will try the bigger jets and see how it goes. thanks.

I have the factory jetting numbers for those carburetors out in the shop. Ill check where they ate stock for you in the morning .
Keith

I had to open up the idle restriction in the metering block a bit on my 770 Avenger. This helps richen the transition circuit.

leave the fronts alone go with 77 max in rear Then test car at track What you may need is a faster opening sec spring esp if running a open element aircleaner. Too many guy's jet like car is running open headers at the track

I had one that was on a pretty stock 440 with headers. They are 72/75 out of the box, and it was pretty lean. 75/78 felt much stronger and got the plugs looking decent.

Major issue with the 770 are the squirter nozzles, only 0.025... Try 0.029 or 0.031 that will wake it up and take the lag out of the qwik rev up on hard acceleration...


Just my $0.02...

Don't stray to far from stock to start but with ethanol blended fuel maybe 74/77 to start then try 75/78 as stated above.


and to bigger shooters think I'd start at 31

Thanks for all of the advise. I will go with the 74/78 combo, and see how that works. Maybe will try a .029 squirter too.