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| 390 Holley Air Bleeds https://www.slantsix.org/forum/viewtopic.php?t=39910 |
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| Author: | SV162 [ Tue Apr 20, 2010 5:51 pm ] |
| Post subject: | 390 Holley Air Bleeds |
Just a quick question for all you 390 Holley users/gurus. Should 390 Holleys (8007) have high speed air bleeds in the primary side? On my 390 they are just brass plugs, like the air bleeds are just blanked off. It has the idle bleeds in the primaries and both high speed and idle bleeds in the secondaries . My carb runs fine, but how??? I thought all holley carbs needed high speed air bleeds in both primary and secondary circuits.  Cheers, Jon. |
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| Author: | DusterIdiot [ Tue Apr 20, 2010 6:06 pm ] |
| Post subject: | Nope... |
Mine don't have them either... The high speed air bleeds determine when the mains will come into play...you plug them and the mains come on sooner...you drill them and they will engage later. The 390 is so small I suspect drilling them would bring the mains on at 23-2500 rpm instead of about 19-2000 rpm... For the slant six I've had to restrict them on larger carbs as the mains would come on too late for the transition to properly cover the gap between idle and the mains without a big pump cam... -D.Idiot |
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| Author: | SV162 [ Tue Apr 20, 2010 6:29 pm ] |
| Post subject: | |
That explains it. Thanks D.Idiot 
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| Author: | DusterIdiot [ Tue Apr 20, 2010 7:16 pm ] |
| Post subject: | Also... |
A note for others that are reading this thread, on the other side the idle air bleeds control a couple of items in your holley 2300/4150/4160: The idle air bleeds are for either adding or leaning the amount of air available to the fuel added by the idle mix screws. This also will do the same thing for the transition slot that picks up after the idle opening is long gone and the plates are sweeping up to open enough to start pulling fuel out of the venturi/boosters. If you get a stumble off idle, but are fine while at cruise rpm... the two ways to "dial" this in is to open the idle screws a bit more and see if the stumble goes away...and/or change to a different accelerator pump cam and set the tension tighter on the pump lever... it is a bit tricky because it's a "tug of war"... you can easily over compensate on both sides...more idle gas = black plugs, slightly worse mileage in town...bigger pump shot/cam = fine idle, big black cloud behind your car everytime you hit the accelerator pedal (most meathead musclecar guys do this and if it's a really rich shot you can wash down the oil off the cylinder walls during cold start ups in the morning....leading to premature cylinder/ring wear). FYI, -D.Idiot |
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