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#1
04-13-2024, 10:29 AM
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Holley tuning ?
I have a fresh mild 400 8.9 comp. with a 2801 cam. I bought a used 600 holley and rebuilt it. I have the idle set at 600 rpm in gear with 16" of vacuum. It runs fine and got it to idle fine. I have a 6.5 pv and 66 jets. Problem I have is the idle air screws are adjusted a little over a 1/4 turn out for the highest vacuum reading. I have read that they should be 1.5 turns out. If I turn them all the way in the engine will die. If i turn them out much more than a 1/4 turn Idle and vacuum drop. I don't know much about the history of the carb as to whether it has been modified anywhere in it's life.
Do you think It is ok to have them a 1/4 turn out? I am going to weld a bung in to use my af meter to see where I am at. |
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#2
04-13-2024, 11:00 AM
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If you do not have a stumble off idle when the motor is up to temp, or a cold starting issue then I would not fret over it especially if you get that gauge fitted up to keep a eye on it.
PS, the jets have 100% nothing to do with idle conditions so leave them out of the equation.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#3
04-13-2024, 12:45 PM
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If it runs good and doesn't foul plugs go with it. Mine are 1/2 turn out.
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Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
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#4
04-13-2024, 05:39 PM
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Put the o2 meter on, got it at 14.7 at idle 800 rpm, 14.2 at cruise 2000 rpms, 12.5 at wide open. I think this is perfect.
I also put a 195 deg thermostat instead of 160. Runs right at 190 and don't get so much condensation out the exhaust and better efficiency. Down side is oil pressure dropped from 40 at 800rpms to 25. Might have to step up to 10-40 instead of 10-30. This just a car for cruising no intention of racing it. |
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#5
04-13-2024, 07:49 PM
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Unless your carb is a 4150 some Holley 600,s have reverse idle air screws. The more you turn them out the leaner the mixture.
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http://www.machdevelopment.com/album...775/527566.htm |
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#6
04-13-2024, 08:12 PM
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I have found sometimes at idle , especially with a little bigger cam the AFR on a wide band may even need to be fatter in the high 12s to 13s. Also too lean a idle circuit carries over often until 2500 rpm and can be a cause of an off idle bog more than any accelerator pump changes can resolve.
A wide band will let you know what each circuit is doing.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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