[wildman72]

I have a402 with and performer Intake holley 670 street avg on it. can any body please give me a starting ponit on the jet size I think they are 65 in it now. I know you alittle rich then drop it down 2 but where to start LOL

 

[Dave427]

I usually start with the stock jetting, which you are correct it is 65 in the primaries. You might have to go a bit richer, but you are correct again go by 2's. The secondaries have 68's in there. So if you go up 2 in the primaries, do the same in the secondaries when you get it close.

Dave

 

[Tom Mobley]

why do you think it needs changed?

 

[wildman72]

spark knock on load timming rite running 110 gas no carbon new heads so the only thing left is fuel.

 

[Dave427]

Honestly the carb is a tad small. But if its spark knocking, try richening a few jets. Are you running vacuum advance?

Dave

 

[wildman72]

yes vac advance set the timming at 8 btc running 110 fuel and yes I know a 750 would be better but dont have the funds to get one at this time.

 

[M.Maner]

Warren,something is way off the mark here. You are basically running no timing, with race gas, and you have detonation. What have you got for pistons in that thing,and what head casting number do you have? Do you know what the ignition curve is? Have you checked your balancer against TDC to see if it's slipped?
Mike

 

[Tom Mobley]

What Mike said, something is out of the ballpark here. Do you have 12.5:1 compression or something? Even if you have 12.5 the 110 should cover it no sweat. What's the big disconnect? Wrong gasoline in the tank? timing marks goofed up? advance mechanism in the distributor boogered? adding jet is not a fix for the problem, it's a cover-up for the real problem.

Something is way out of whack here.

 

[wildman72]

Yes thats what IM thinking too. well this is it I doing the Intake gasket checking all vacumm ports and resealing all checking the advance in the disy. going thrught it with a fine tooth comb.will let you know what i come up with.also going from 65 pri and 68 sec to 70 pri and 72 sec.a 50cc acc pump and a bigger squrter.the heads are 3964290

 

[Tom Mobley]

IMO you need to double check the timing marks are right before anything else. there's many discussions on here about this and how it's properly done.

 

[wildman72]

mite have found the problem my vacume line to my power brakes had a little hole in it.will let you know tomarrow when I get it going.l getting old cant do this like I use to lol

 

[wildman72]

well its not running yet went and took of the timming chain cover and checked the cam timming all was right there.

 

[M.Maner]

Warren,what was being suggested to you,was a check of the balancers TDC mark against the actual TDC position of the #1 piston.
Mike

 

[wildman72]

well her it is running and idels good check tdc balnacer was off a bit had a guy who builds these eng and race them give me a hand with it. It still has spark knok on hard acc no mater what we do hes is stump and beleave me that hard to to do.they are dome pistons running 12.5 to 1 comp.

 

[wildman72]

this is what I did to git rid of my spark knock no vac advance no pcv valve now no spark knock. it good haveing friends in drag racing.