holley help
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Senior User
Joined: Aug 2006
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holley help
I have a 1988 ford truck with a 302 and aod tranny, mild cam .498 lift .278 adv dur. hei distributor, 9mm ford racing wires power plus intake typhoon, right now i have a 750 vac. sec. everything else is stock runs good but kind of bogs down when 2nd gear kicks in is it too much carb for this set up.
Elder User
Joined: May 2004
Posts: 565
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From: saxton pa.
A 750 vacuum sec on a heaver vehicle with a 302 is a bit too big
, A 600
vac. sec would give better throttle responce, and be easier on fuel. A smaller
carb will give all around better drivability & economy.
Have A Good Day--------Hotwrench
, A 600vac. sec would give better throttle responce, and be easier on fuel. A smaller
carb will give all around better drivability & economy.
Have A Good Day--------Hotwrench
Moderator
Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
Yes the carb is a bit large, a 600 will give better performance.
But the problem you are having sounds like it is running out of fuel.
It could be from a weak fuel pump, partially clogged filter, a bad piece of rubber fuel line, or the floats adjusted too low.
But the problem you are having sounds like it is running out of fuel.
It could be from a weak fuel pump, partially clogged filter, a bad piece of rubber fuel line, or the floats adjusted too low.
Post Fiend
Joined: Oct 2003
Posts: 9,176
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From: Western Central NV
A 750 is abit big. What secondary spring are you running? Is the check ball in place? What jets are you running? You can run that 750 but your going to have to tune it. I agree what is your fuel presure?
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On the spring I wouldnt know it still has the original one since I bought it and on jet I have 80 in the front and a .37 squirtter I had to go larger because it would backfire with smaller jets and squirtter. As for the check ball it is in place the only other thing is probably to adjust the kickdown cable first gear shift around 20 mph but third gear goes in at around 4o to 45mph
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Post Fiend
Joined: Oct 2003
Posts: 9,176
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From: Western Central NV
Originally Posted by marioc956
On the spring I wouldnt know it still has the original one since I bought it and on jet I have 80 in the front and a .37 squirtter I had to go larger because it would backfire with smaller jets and squirtter. As for the check ball it is in place the only other thing is probably to adjust the kickdown cable first gear shift around 20 mph but third gear goes in at around 4o to 45mph
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Tuned
Joined: Oct 2006
Posts: 361
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From: Eagle River, Alaska
Lean run has caused back fire in my case. burnt down a car with a fuel line break. A vacume meter in the cab will tell alot. your vac. at shift may be to low for the Cfm of the primaries with stock jets and air bleeds . Carb tunings a bear with out a dyno,or exaust test, but can be done well with trial and uh, some error . Check the tail pipes for black soot. indicating rich mix. check plug color after running for a drive. Your holly has a power valve enrichment system that prob. isnt right for your combo of parts, back to checking vacume readings and so forth. lots of variables . Vac. runs alot of it . The cam you list has a healthy lift with mild duration.Sounds good for 3spd truck autoTrans shift pionts ,but rearend ratio and possibly, gearing of the auto overdrive may be keeping RPMs alittle low . Small blocks enjoy RPMs. As well ,to fully utilize the larger carb( CFM rating ), RPMs welcome. Best wishes.
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