so I've been doing a lot of tuning lately and I've gotten rid of every problem except 1. when i step on it it barely stutters and then it gets going. and also in 5th at anything below 55 it'll bog a bit. and going up a hill it'll struggle a bit and bog as well in 5th and 4th depending on the speed I'm at. and also if i step on it and then let off and press on the clutch it'll just cut out and die. is this a fuel issue or a timing issue? or maybe something else? SPECS: roller 302 bored 30 over with a rolling thunder cam, e7 heads, weiland dual plane intake, holley street avenger carb (stiffest secondary spring, 35 shooter, 5.5 power valve, factory jetting), cam timing advanced, backed by a t5 trans. it has a HEI distributor with a spring kit (am using lightest springs) set to 18 initial and total advance at 38. thanks in advance!!
sounds like the low speed air fuel ratios are wrong. these can be adjusted with the idle mixture screws to a small extent. also the air bleeds can have an effect on this. you may want to try a different vacuum level power valve. the hard part is knowing if you lean or rich. im thinking its rich but not completely sure. does your distributor have a vacuum advance?
yeah the dist has vacuum advance. it has 20' of advance. and i got a spring kit so i had a lot of springs to choose from to tune in when it comes
what cfm is your carb? is the vacuum advance hooked up to the ported vacuum port or manifold vacuum port on the carb?
A rich condition won't cause one to die, I say it's lean... If it's any thing like the 670 Avenger on my 428, you'll need to increase jets at least two to three sizes in each end...
its the 670 street avenger. i have the vacuum at full vacuum. i did what you said earlier bryant and got the stock power valve (6.5) and it works beautifully. much smoother power and carries on for a longer rpm range then it did before. made a 1000% improvement. diddnt know the power valve did that much to be honest... it doesn't cut out and die anymore either. I'm still hearing / feeling a SMALL stutter at around 3-4 thousand rpm at mid too full throttle, but it is very well improved. virtually perfect under normal throttle situations.
that 3k to 4k rpm stutter is about when the secondarys should start opening. maybe go to the next softer spring on the vacuum diaphragm. i stopped messing with vac secondary carbs years ago. i have more fun with double pumpers so im drawing on old dusty knowledge on the vac secondary tuning.
Maybe even a 7.5 or 8.5 power valve. I had an 8.5 in a mild 302 with extremely small cam and there was no hesitation at any rpm, the thing was snappy as hell. That was a 650 vacuum secondary carb with a light spring.
the rollin thunder is around .520 at the valve i don't know that this cam will like a bigger power valve or not...
its a manual trans. 12 to 13 at idle that why i think the valve should be good. but i suppose trying one wouldn't hurt
I would try it if it were my car. The worst thing that could happen is you have to take it back out and you lose a few bucks.
