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Old 10-06-2012, 08:28 AM
cdminter59 cdminter59 is offline
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SBC 350 misfire at idle in gear

Originally Posted by ragee517 View Post
Timing is around 30 or 50 its not near the mark. Don't know if its helpful but with the vacation advance unhooked it still makes the noise. It sounds like its up front of the block or by the trans. It doesn't always seem to be in the same spot and as soon as I let off the throttle its gone.
Do you have a timing light with a advance dial on it? It makes it easier to check the mechanical advance. Start by setting the initial timing at 12* BTDC with vacuum hose off the distributor and plugged. Reset the idle to 800-900 rpms. Second step is checking the mechanical advance. Have someone rev the motor to 3000 rpms and hold it. Point the timing light at the scale and turn the advance dial until the line on the balancer is on zero. Adjust the distributor until you have the timing light reading at 36*. You may have to buy an advance kit to change springs to get the mechanical advance all in by 3000 rpms. Your timing curve should be 12* BTDC at idle and starting about 800 rpms the mechanical advance should gradually add about 24* at 3000 rpms. Now unplug the vacuum line and connect it to the full time vacuum port on your carburetor. You can check the timing again at idle and should red 50*-52* with the vacuum connected. Here is an article on HEI distributors to read.
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