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Discussion Starter · #1 ·
my th350 needs a vacume on the side of it
can i take this from the small pipe on the side of my holley carb

thanks
 

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drag race addict
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No, unless you want the trans to go into 2nd everytime you come off the throttle.
Permanent vacuum only, ie under the throttle or direct from the intake.
 

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Discussion Starter · #3 ·
ahh ok so can you tell me what the small pipes on the holley should go to then
there is a big one at the bottom and also a small 1 at the bottom in the front and also a small 1 high up on the side
 

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drag race addict
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Small one up high = ported vacuum.That is for the distributor if you don't want vacuum at idle. Small one under the throttle = permanent vacuum. You can use that. The big pipe is permanent too, and used for either closed engine breathing or a servo.
It's better to have a feed for the modulator directly from the intake, there is usually a pipe plug you can remove, but at a pinch you can use the little one under the carb.
 

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Discussion Starter · #5 ·
ok thank you for the advice mate
my inlet manifold does have holes in it but they have blanks in them
ill see if i can find a adapter for 1 of these holes

thanks
 

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motors built to combat smog, they used various things to make your engine greener, ported vacuum, charcoal canisters, EGR, low compression
 

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If you have modified a smog motor for more performance you may find it idles better with full vacuum, my motor idled rough with ported vacuum so I speed up idle which exposed transition slot in the Holley carb, then mixture screws don't work! I connected to full vacuum , reduced the idle speed screw, jobs a goodun!
 

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After the oil crisis in the early seventies the cars got heavier and made less power, 5 mph bumpers, lower octane unleaded fuel and emission reduction all played a part, fortunately in this country we can tinker with it, as far as I know you cannot in California, dont know about the rest of America
 
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