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 holley tuning 
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Post holley tuning
Alo alo everyone :D this tuning question(s) is geared to the Holley double pumper individuals. So heres what I got.

10.5:1 compression rebuilt aluminum headed sbc, with a mild cam, rpm airgap, and holley carb(s). Heres my issue(s) I have 2 different carbs, both rebuilt. One is a 600cfm, the other is 650. timing is set to about 34 total timing.

1. when Im cruising for a while, be it highway or the street. When I drop it into neutral ( about to stop or slow down ). The motors rpm drops to 200 rpm, and will often want to stall. Both carburetors do this, and yes the needles have been adjusted, flaps, and I have a solid 17-18 vacuum. The only way I can stop it from stalling, is if I downshift through all the gears, slowly and ease it into an idle rpm.. OR i drop it into neutral and feather the throttle to keep it idling. ( both carburetors did this ) Also, once its eased into idle, it idles beautifully. So no Im not feathering it every time the car is idling, I only do it when the car is slowing down to an idle.

2. When Im at 1700-2000 rpm ( 2nd, 3rd, or 4th gear ). if I punch it, the car jumps forward as it should ( yes its got enough fuel with upsized squirters ).. But, it leans out after a second past 20:1 afr for a few seconds and stutters, then it picks up and runs a solid 12.5 -13 ish AFR through the rpm range. ( this is at WOT held open )

Issue 1. Ive tried playing with timing, and needles etc. cant figure it out.
Issue 2. Ive tried upsizing the squirters and helped a bit, but it still leans out after the pumps are emptied out.

Any help is appreciated, so long as its not ( rebuild the carbs ) lol.

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Sun Feb 09, 2014 2:05 pm
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Post Re: holley tuning
Raise your primary float height up a little. I always start with no dribble on level ground when idling for the fronts and just a little dribble on the rears, and it usually works fine but sometimes the level needs to be increased/decreased pending the car and set up. It sounds like the mains stop flowing on transition until the air speed is enough to draw the fuel into the venturi ( thinking this is the lean condition after the pump shots are done ) Might want to try some different power valves up/down a few and see if that helps? Could be fighting itself when the vac signal changes rapidly like it does on decel. Its been a while since ive messed with carbs, cant say i miss em much.

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1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

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Sun Feb 09, 2014 3:45 pm
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Post Re: holley tuning
tnx cam. I actually also realized that maybe my pump sizes need to increase, it might just be finishing the full shot as you stated too quickly. im fairly certain upsizing to larger diaphragm will solve that issue. Also it has come to my attention that with a standard transmission, it may be necessary to get a throttle return dashpot. which basically dampens the rapid deceleration of rpms when I let go of the throttle so it eases into idle.

Any one had any experience with these ?

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Sun Feb 09, 2014 9:15 pm
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Post Re: holley tuning
LS swap it and be done with it LOL

Or do the fast EFI swap and done

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Mon Feb 10, 2014 12:24 pm
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Post Re: holley tuning
I did use one of those "dashpots" once for AC load. Idle wasn't enough for AC so I installed one that raised the idle a bit on AC request. It also mellowed the thing out on shutdown as it completely closes the throttle blades. Could maybe wire it up to a vac signal switch so it holds more idle RPM until there is sufficient vacuum. Something like that should help

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1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Mon Feb 10, 2014 12:41 pm
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Post Re: holley tuning
LoL ray

yea I more or less tuned it a bit better.. I put a softer power valve in it, and it helped out with the lean condition a bit. and I also downsized the squirters a tiny bit. Tnx!

And I will look further into the dashpot system.

thank youzz

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Wed Feb 12, 2014 7:26 pm
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