Centrifugal advance question

[tri-power 250]

I just checked my centrifugal advance with a dial back timing light, here are my advance numbers,
4*@750, 24.8*@2400 and 27.5*@3500. The vacuum advance was plugged. Do these numbers indicate the advance is happening too fast?? I am just learning how to read what the advance numbers.

The issue I am having is serious detonation at 60 mph @ 2500 rpm. That is why my initial advance is set so low to help reduce the detonation at cruise and my vacuum advance is plugged. I am getting a new set of advance springs this week and after installing them, I'll post the new numbers.

Ken

 

[wsa111]

Ken, the advance is coming in too fast & the total is a little high. I like to see the centrifigual advance on a stock engine in by 3000 engine rpms.
Are your advance numbers not including the initial advance.
What are the specs on your engine?? Compression, cranking compression, fuel octane used, carburation, A/F ratio.
Without all of this information it would be a guess as to what your engine needs.
The only way is to dial in a distributor on a sun machine once all the above information is known. Bill

 

[tri-power 250]

Thanks Bill,
My 250 is basically stock. The head has been shaved .070, big valves added, 2bbl direct mount. The idea behind this engine was to get as much out of it before the new engine replaces it.
Ken

 

[CZLN6]

howdy Ken:

Your curve is a little slow and a bit too much for my taste. I like to see all centrifugal advance in by about 2000 to 2400 rpm. And a total of around 20 - 24 degrees centrifugal. Then I add initial to about 16 to 20 degrees to suit the climate and the engine need.

You didn't say what you initial setting is. But, is the pinging at a steady speed or acceleration? What do your plugs look like? Just some thoughts.

Keep it coming.

Adios, Bill

 

[tri-power 250]

I installed the new springs, Steve Davis of DUI Performance Distributors, sent me. Great news, no detonation! The engine is running great.
My lesson learned is deal with great companies and they take care of you. If you are interested in buying a distributor, please go to: www.performancedistributors.com.
Ken