Re: Looking for a timing Authority... Re '39 Six

Posted by Ross On 2016/12/25 9:25:55

If you have your timing set at tdc with the engine running you will find that the engine will speed up noticeably as you advance the timing to the correct position of 3 to 5 degrees BEFORE tdc.

If you move the distributor in the opposite direction and for some reason end up with the timing 3-5 degrees retarded, or AFTER tdc, you will have a very warm engine with no power.

Perhaps the terms are confusing: the spark must occur in ADVANCE of the piston reaching TDC on the compression stroke so that the fire has a chance to get going and push the piston down on the power stroke. If the spark occurs after tdc much of your power goes shooting out the exhaust valve when it opens. In addition, the faster the engine is running, the sooner the spark has to come as it takes a finite amount of time for the fuel to burn. That is why distributors have advance mechanisms.

I stand by my post, #7, on your original thread about this car.