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#1
02-20-2007, 12:01 AM
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Holley carb power valve questions
I'm rebuilding a Holley 4557 for my 70 L78 Camaro. It looks like it had a 10.5 primary and an 8.5 secondayr power valve. The rebuild kit looks like it has a pair 6.5 valves? Is that too low to go compared to stock? This carb is really old and has been sitting for years so I'm doing a cleaning and rebuild and can't compare before and after. I'm thinking I need to stick with someting closer to stock instead of the 6.5's that are in the kit.
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69 Z28 JL8, #'s match - being restored 
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#2
02-20-2007, 12:25 AM
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Re: Holley carb power valve questions
I'm running the same power valve numbers 10.5/pri--8.5/sec on a 3310 that I use on and off and the car responds real good and idles well with no surging--Bring your engine to operating temp and take a vac.reading and then step down 2 numbers....to start.
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#3
02-20-2007, 12:55 AM
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Re: Holley carb power valve questions
Our L72 engine came with 6.5 poweR valves front and back.
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Chevelleless after 46 years......but we did find a low mileage, six speed, silver 2005 Corvette. It will just have to do for now. 
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#4
02-20-2007, 01:08 AM
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Re: Holley carb power valve questions
Jeff;
The original power valves for a 4557 are 8.5's both front & rear. If your engine is stock, I'd stick to that. Eric
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#5
02-20-2007, 01:29 AM
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Re: Holley carb power valve questions
The engine has 2" primary headers, HEI distributor, I think they're 1971 oval port heads(to lower compression), stock flat L78 intake and I'm going to assume stock cam. If I remember correctly, when I checked the compression and vacuum it was reading around 13 at idle. So I'm thinking the 6.5's will be too low. I would rather get the power valves right the first try so I'm in no hurry. Thanks guys.
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69 Z28 JL8, #'s match - being restored
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#6
02-20-2007, 01:38 AM
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Re: Holley carb power valve questions
Jeff;
Check your PM's. Eric
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#8
02-20-2007, 05:07 PM
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Re: Holley carb power valve questions
[ QUOTE ]
We run a 65 in the front and a plug in the rear of ours...seems to work...  [/ QUOTE ] Ditto that setup on the Deuce
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Marlin 70 Yenko Nova-350/360, 4speed M21, 4.10 Posi (Daddy's Ride) 69 SS Nova-396/375hp, 4speed M20, 3.55 Posi (Benjamin's Ride) 67 RS Camaro-327/250hp, 2speed Glide, & 3.08 Open (Danny's Ride)
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