700 Holley or keep my 850 Holley? HELP! - Team Camaro Tech
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post #1 of 6 (permalink) Old Jul 22nd, 00, 04:11 PM Thread Starter
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Join Date: Jan 2000
Location: Highland Village, TX, USA
Posts: 138

I'm working on my car tonight and I think I 'm getting some fuel foul on my spark plugs. I currently have a 468 in a 69 camaro with a 850 holley producing now, a little over 500 HP. I'm thinking of trying a 700 Holley I have in my garage with a raceing kit put on it. Which makes it maybe a 740.

I'm also very concerned because I think I'm seeing oil on my spark plugs. Oil foul on a new engine. I sure hope not.

So, with this 700 holley with a trick kit on it, or keep the 850 holley. With the 850 I get a liitle bog off the line. I guess I'll loose some top end power, but should get a better response at low end.

Watcha think???
Thanks for the help!
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post #2 of 6 (permalink) Old Jul 22nd, 00, 04:34 PM
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Location: Hayward,Ca,USA
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A trick kit is just a rebuild kit that comes with a variety of parts which are used for tuning. I would spend some time tuning your 850 or take it to a place and have them do it. A short while ago a friend of mine had carb problems with his freshly rebuilt 428 in his GTO so he used a carb that was sitting on his shelf. His car ran fine around town so he made a couple of full throttle passes with it, turns out the carb was very lean because of a blocked passage in his secondaries. To make a long story short by the time he was finished rebuilding his engine agian it cost him $3500. Good luck.

Steve R.
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post #3 of 6 (permalink) Old Jul 22nd, 00, 07:00 PM
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Location: Whitehouse, Texas, USA
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The smaller Holley will give better throttle response, and probably be ok for everyday street driving, but will be too small for all-out performance on a 468 cid, 500 hp engine. I would keep the 850 on it, and tune it correctly. It sounds like you might have the wrong power valves in it, that are opening too early at idle and low rpm, and "sooting" the plugs. Carb size selection is really based on rpm useage, and engine size, and has nothing to do with mixture. Check your engine vacuum at idle,(in gear if it's an automatic), and select a power valve that is 1-1.5 sizes lower than your vacuum reading at idle. If you get an off-idle "bogg" when the throttle is cracked open, try larger size pump shooters. Hope this helps.

[This message has been edited by Peace69Z/28 (edited 07-22-2000).]
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post #4 of 6 (permalink) Old Jul 23rd, 00, 12:56 AM
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Definately tune the 850. I found the power valve loose in my holley dp that was causing the plugs to foul. Also, I believe the size of the power valve should be 1/2 the vacuum reading. This is what the holley tech line told me. I have 14" vacuum and use a 6.5 power valve.
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post #5 of 6 (permalink) Old Jul 23rd, 00, 01:39 AM
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Location: Atlanta, GA
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How would an out of tune carb, be OIL fouling his plugs?? Sound like valve guides/seals to me. Another vote for sticking w/the 850 cfm and tune it or have it tuned.

[This message has been edited by 70 RS/Z-28 (edited 07-23-2000).]
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post #6 of 6 (permalink) Old Jul 24th, 00, 02:00 PM
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Location: Valencia, CA USA
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I'd worry more about the oily plugs than the carb...first things first. You said that it is a new engine, do you have a functioning PCV system hooked up? Oh and I would also tune the 850, you'll get more top end with it.
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