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Odd timing question

I recently purchased a 1970 vette w/ 350 small block. The spec manual say to set the timing at 6 deg BDC. However in order to get the car to run properly I had to set it at 12 degrees. What might cause this.

One theory I had was the person who rebuilt the engine set the timing chain on a number of spokes off. Secondly I'm curious if this could cause any other timing problems. Although the car runs fine I'm curious if this leaves the engine with little room for timing advance.

Your opinions are appreciated

Reply to
Eric Aiken
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Reply to
George

The distributor will have a certain amount of mechanical advance and a certain amount of vacuum advance, all of which are above whatever static advance you set it at. Usually you set it to a spec with vacuum line off and plugged, so you have just the mechanical advance working. Since the mechanical advance will come in variably depending on rpm, and depending on the weights and springs installed, it's really common to get some change. All that really matters is if the engine is running well. Typically, you'll get ping under load at lower rpms, and detonation under load at higher rpms if the timing is too advanced

I set timing based on total advance by running the engine at a speed so that it is at maximum mechanical advance. But you have to know what to set it to - I usually find that out on a dyno. If it's a street car, just set it so it runs good.

Brian

Reply to
Brian

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