Wrong Power Valve? - Team Camaro Tech
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post #1 of 3 (permalink) Old Jul 29th, 03, 02:37 PM Thread Starter
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Matt Jones
 
Join Date: Jan 2002
Location: Renton, WA USA
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Question

My 355 has an Isky 270 cam (221/221 108LDA), Vortec heads, 9.8 compression, and a Road Demon carb. It pulls 11-12"Hg of vacuum on my 5" gauge, and about 12.5-13"Hg on my 1" gauge (not sure which would be more accurate). Currently, I've got a 6.5" PV in the Demon.

My problem is at WOT from a stop. The engine revs up to the converter stall (2200RPM), then stutters like the A/F just isn't correct. I don't see any black smoke, and there's no backfiring through the carb. At about 2600RPM, the engine takes off and pulls up to 6200 as it should. Also, the motor can't even break the 235/60 tires loose, it just stutters until about 2600. At about 25MPH, I *think* I feel the engine stuttering lightly, but I could be wrong.

I think I've got the accelerator pump worked out (green cam, #31 squirter), 4-corner mixture screws at about 3/4" turn out, and I'm using the plain vacuum secondary spring. I use this spring because it gives the best performance when the engine is at WOT in high gear. Ignition timing is at 22* at idle (using vacuum advance), and the plugs show a rich condition (although engine as been idling alot lately). I'm using the stock jets, which I believe are 70 in front, 78 in back.

Phew, I think that's it. [img]graemlins/boring.gif[/img]

Matt Jones
Lead Mechanical Engineer
Art Morrison Ent. Inc.
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post #2 of 3 (permalink) Old Jul 29th, 03, 04:13 PM
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DOUG G's Avatar
 
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http://www.mortec.com/carbtip1.htm

try this for more info.

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #3 of 3 (permalink) Old Jul 29th, 03, 04:51 PM
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Location: Concord Cal. USA
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You have used up your acc. pump circuit before you need it. When the convertor locks that is when you need the extra fuel. Try bringing in the acc. pump a little later.
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