Dear Auto Advisor,
I am down in PC for my summer vacation and my older classic car has get up and go problems.
My question is "How much mechanical advance should I get from my H.E.I. distributor?"
The car I am working on is a 1974 Pontiac Trans Am with a 350 engine.
I know that with the vacuum advance disconnected, I only see 5 or 6 degrees of advance when I bump the throttle.
Is this enough? The weights and springs move and snap back freely inside the distributor.
I hope this makes sense to you.
Follow these steps below to properly check your TOTAL Spark advance of your distributor on any car with a distributor.
1) Have an adjustable timing light hooked up and note what the timing is at
idle with the vacuum advance hooked up.
2) With your car engine is at normal operating temperature.
3) Hold the engine rpm’s steady at 2500 and “adjust” the timing light to see the TOTAL
Timing advance is.
Most vehicles have a total spark advance of 35 to 45 degrees. With a base timing of only 2 to 6 degrees with the vacuum advance disconnected at idle. On your Pontiac it is 18 degrees if my memory serves me correctly.
The reason you need to advance you timing at higher speeds is to give the gas time to burn completely. Gas vapors burn at the same speed, no matter if you are going 5 mph or 105 mph. So the faster your engine runs the more spark advance the engine needs to burn your fuel completely to save fuel and have proper performance and power.
Peace and prosperity in 2012!
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