I have chevy with a mild 350 with vortec cast iron heads.I am running 10 initial and 30 total advance at 3000 rpm.It has a street avenger 670 and runs really good ,great power,but it idles rich I can only get the air/fuel screws 1/2 to 3/4 turns out from seated.Also it runs 17" of vac. Could I have a blown power valve even if it has the blow out protection? How do you tell if the pv is bad other than just replacing it? Any other ideas to check
I had the same problems with the same carb! Couldnt get the idle mixture to do anything. I put on a bigger carb so tht doesnt help. Holleys website has a great tech help section. Worth checking it out Posted using the Full Custom H.A.M.B. App!
I have been through their tech section and talked with them over the phone a couple times not much help.I had the 770 version on my chevy II had the same problem never did get it sorted out before I sold it.
Check both float levels, also remove idle mix screws and blow these and idle air bleeds (small holes inside air horn facing up) with compressed air or carb cleaner. Let us know what works Greg Also, if you're not running a fuel filter put one in.
I have had a few holleys and all have been good and trouble free. The street avengers are another story,both of them have nothing but problems since day one.I guess I am a slow learner becouse I bought the 2nd one.
What Hoop asked was my first thought, Its getting fuel be it from crap stuck in the needle a seat, a float to high. Perhaps even a shifted gasket on the PV leaking fuel into idle circuit.... When you screw both in, the engine should stumble and die...
I have always used a vacuum guage for tuning.I pulled the power valve out it seemed to be fine,I couldn't suck air through it so I assume its ok.Blew out all passages in the metering block including needle seats.put it back together and I still can,t get it to lean out at idle.I did how ever get it to stumble and die when I screw in 1 of the needles but, it wouldn't do it with the other . The float levels are at the bottom of the sight hole to where you have to shake the vehicle to make it come out.
Timing is too soft,total without vacuum advance should 35,not saying this is the problem,just added to it,try bumping the base up to 15 and try it.
This motor is a 69 bottom end with the vortec iron heads I have about 2500 miles on fresh build.Granted it has seen alot of garage time and not much road time at all. From what I have read from GM and other sources recomended no more then 32* total.At 30 total I am just below where it pings it might be a little conservative but I feel comfortable with it there. I have the part# 604 circle track motor and the paper work that came with it also said no more then 32* total.So I think I am in the ball park timing wise.
After pulling it apart and blowing all the passages out 3 times I got it to where it idles good and not so rich. the air/fuel screws aactually work.
I haven't and won't buy a 2nd one---talk about a PITA---tweaked it I don't know how many times and have had help from friends and still no results. Should have bought an Edelbrock.
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