new 4150 street hp carb.runs great otb.my only issue is in park at idle if i jab the throttle fast it will hesitate a bit.im pretty sure its a pump shot issue.i get gas as soon as i hit the throttle so im sure the adjustment is good,im thinking of going up on on squirter size.im i going in the right direction?float is set to just dribble out the hole.timing is set at 38.deg.with vac.adv.not in use.chrome ign. box.under load going down the road when and full throttle is applied there is no hesitation.
holley 4150 tune,one issue
- Thread starter jdsduster
- Start date
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kennygene
Well-Known Member
Change your cam first, my 650 hp came with a pink cam an I went to the more aggressive cam and bigger squirter. Stock squirter was I think 28 and I went with a 40. I'm sure there is still more fine tuning to do but it's running much better now.
What is engine timing at idle? Put a timing light on it at idle and see where it is. If it's not in the 15-20 range, maybe more, it's not correct. Simple test. loosen up the hold down clamp and twist the distributor a little CCW, if it picks up rpm, it wants the timing. Reset idle speed and do it again. As long as it doesn't drag the starter or kickback, you'll be ok.
This gets back to there are two ways to set timing, the lazy way (total) and the good way, initial first.
Most mopars want in a lot more than the book or most distributors will allow when setting using the total method. You'll likely have to adjust the mechanical advance in the distributor. There are a ton of threads on the subject of setting up timing/distributors on this site.
Lots of assumed carb related issues aren't really carb issues at all. The issue is rooted in the ignition system.
This gets back to there are two ways to set timing, the lazy way (total) and the good way, initial first.
Most mopars want in a lot more than the book or most distributors will allow when setting using the total method. You'll likely have to adjust the mechanical advance in the distributor. There are a ton of threads on the subject of setting up timing/distributors on this site.
Lots of assumed carb related issues aren't really carb issues at all. The issue is rooted in the ignition system.
crack,ill check initial in the morning.i thought you never worried about initial and set it at total,i mean it really runs strong other than this issue. thanks
I just fixed a 340 with the same deal. If the engine cranks a bunch to start or you need to give it gas while cranking to fire, it's not right. That's MP manual total timing method and doesn't work best on street cars.
Soggy off idle. It had 10* initial, now 20+ and it fire right up and the throttle response is snappy and no longer bogs at all.
Let initial fall wherever works OK on a race car that's never street driven. To me it's unacceptable and cars will perform better in the 60' when the carb/ignition are tuned well. Low initial timing usually has a smell out the tailpipes like a fuel truck because the carb has to be rich to cover the inefficiency.
Soggy off idle. It had 10* initial, now 20+ and it fire right up and the throttle response is snappy and no longer bogs at all.
Let initial fall wherever works OK on a race car that's never street driven. To me it's unacceptable and cars will perform better in the 60' when the carb/ignition are tuned well. Low initial timing usually has a smell out the tailpipes like a fuel truck because the carb has to be rich to cover the inefficiency.
got it.
kennygene
Well-Known Member
I'm running 14 initial and 34 total with a timing limiter installed from 4secondaflat.
I still had trouble with acceleration in the primary side with the hp. I think I went from pink to the black cam but not sure. I'll try to remember and check it this evening.
I still had trouble with acceleration in the primary side with the hp. I think I went from pink to the black cam but not sure. I'll try to remember and check it this evening.
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