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#1
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I have a vacuum problem with my 1966 GTO. It is a stock 389 4bbl automatic.
The block has been bored .040 over and the heads have been fitted with screw-in rocker studs and big block chevy adjuctable rockers. The pistons have had .060 removed to lower the compression ratio. The cam is an Ultradyne(H6818) with a duration of 272/276 and a .454 lift and 112 degree lobe separation. I replaced the original Carter AFB with an Edelbrock EDL-1406. After isolating all the vacuum accessories, the vacuum reading does not exceed 16 inches after adjusting the ignition timing for maximum vacuum. Do I have a bad intake manifold. How do I check it? |
#2
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I have a vacuum problem with my 1966 GTO. It is a stock 389 4bbl automatic.
The block has been bored .040 over and the heads have been fitted with screw-in rocker studs and big block chevy adjuctable rockers. The pistons have had .060 removed to lower the compression ratio. The cam is an Ultradyne(H6818) with a duration of 272/276 and a .454 lift and 112 degree lobe separation. I replaced the original Carter AFB with an Edelbrock EDL-1406. After isolating all the vacuum accessories, the vacuum reading does not exceed 16 inches after adjusting the ignition timing for maximum vacuum. Do I have a bad intake manifold. How do I check it? |
#3
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The first thing we need to know is, how does the engine run? If you have a steady needle at 16" with no engine miss, you may not have a problem. Why are you adjusting your timing using a vacuum guage? You should be using a timing light, then adjust your idle mixture to the highest reading with the vacuum guage. If you think you have a vacuum leak, use a propane torch (un-lit) and move it around the intake manifold. If there is a leak, the engine idle will speed up where the leak is. If all else fails, check your cam timing. Late cam timing will also a cause low manifold vacuum reading
------------------ "Run wild with an Indian, not with the crowd in a Chevy" Check out my restoration at http://members.aol.com/jetmech15/gto
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Less said,,,,,,,, Less mended. |
#4
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I tried the propane torch. I get no increase in idle speed. Could this be retarded
cam timing? How do I check the cam timing without removing the timing chain cover? I don't beleive the cam is at all radical. [This message has been edited by Ccass (edited 11-13-2000).] |
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