1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

holley 4160 jet size for a 12a

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Old Feb 11, 2003 | 01:43 AM
  #1  
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Question holley 4160 jet size for a 12a

I just purchased a used holley 4160, 600 cfm. I know it is large for my motor although I did get it for a good price. I was wondering if any one out there would know what jettings to use for a stock port 12a with a racing beat intake manifold and headers? thanks for any suggestions
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Old Feb 11, 2003 | 01:50 AM
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don't forget if the carb hasn't been modified to work on a rotary then you'll need a open spacer between the carb and manifold
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Old Feb 11, 2003 | 08:50 AM
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Originally posted by Hyper4mance2k
don't forget if the carb hasn't been modified to work on a rotary then you'll need a open spacer between the carb and manifold
...now I am curious, why and open spacer between the carb and manifold.

I think I know the answer, I just want to compare notes here.

*shines spot light at you*

-Error
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Old Feb 11, 2003 | 02:12 PM
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yeah why the spacer
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Old Feb 11, 2003 | 04:01 PM
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damn i can't find the post i started about it, but it has to do with the fact that there has to be vaccume on both the primaries and secondaries for the carb to run right if you look at the stoc manifold there are little slits between the primaries and secondaries
and when rb makes the kit they modify the carb not the intke manifold so there is the need for the spacer like so

on the stock carb you can see the link clearly on the front rotar on the rear rotar its located below the butterfly

Last edited by Hyper4mance2k; Feb 11, 2003 at 04:05 PM.
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Old Feb 11, 2003 | 04:07 PM
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there is someone on here who can explain it more clearly than i could i belive it was mar3 who told me aboot it.
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Old Feb 11, 2003 | 04:31 PM
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Hmmm...now I gotta find out if my RB modded holley has this. I will have to check when I get home. :P:

-Error
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Old Feb 11, 2003 | 04:41 PM
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hey if you didn't notice error that your stock manifold
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Old Feb 11, 2003 | 04:41 PM
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Hyper4mance2k, I just realized that pic you posted is my intake on my '83 before I installed the RB intake.

http://3rdhour.com/gallery/album03/originalIntake

d'oh

-Error
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Old Feb 11, 2003 | 05:07 PM
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this is the old post with nice info!!
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Old Feb 11, 2003 | 06:34 PM
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Man, I totally forgot about that thread. That is when I first got my carb...that's been a good while back...LOL.

-Error
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Old Feb 11, 2003 | 07:24 PM
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its a good one
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Old Nov 3, 2003 | 01:11 PM
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Open spacer sucks ***! Have any of you tried it with good results? I tried it a few days ago and took it off as fast as I put it on, with a few jet changes in between!
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Old Nov 3, 2003 | 05:20 PM
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From: Trying to convince some clown not to put a Holley 600 on his 12a.
I don't know as much as Carl does about the open plenum design and when it's good - when it's not, ect. But I do know that if you utilize an open plenum you'll change the signal strength to the main jets and the air bleeds will HAVE to be recalibrated to match the fuel jet selection.
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Old Nov 3, 2003 | 06:33 PM
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Thats basically it Sterling. 813, were you using this on a RB holley? or a stock Holley. Actually that is a big plenum. I'd try a split, dual plenum spacer. Even on a V8, an open plenum spacer moves torque up the power band which kills the low end.
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Old Nov 4, 2003 | 07:46 AM
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Not a RB Holley. That is weird Carl, because my top end is what suffered? I truly dont mind a **** low end if the pow is where it is supposed to be! Somebody in another thread asked me if I changed my accelerator pump, which I didnt. Do you think that may make changes in the performance of the carb? The problem I experienced was when I would hit the gas to fully open the carb, the engine would bog and want to die. If I would slowly open the carb to full throttle it would open up but felt weak in the higher rpms ? Actually the low end felt ok. Iam not a big low end power kind of guy, so I really dont concentrate on the low. I like 5 and above that wants to shove the seat in your back! Which I am still chasing, but had with a damn stock carb on a 4 port/street port 13b!
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