jensenracing77

The stock Jetfire setting is just 10 degrees initial timing and no other information. I had it set at 10 and then checked it at 2500 RPM and no load. I had 45 degrees total. I would assume this is mechanical and vacuum at full. I feel like 45 is to much but I don't know. I did not think to check just the mechanical advance without the vacuum advance hooked up. I have very limited experience setting the timing other than initial so I am not sure what is right and wrong. Is 45 to much? I feel like it is. It is a 215 with a 3.5 inch bore. Any input from the experts on this?

BangScreech4-4-2

Not an expert by any stretch, but I do know that timing is always checked with the VA disconnected and the hose blocked.

oldcutlass

You need to note what the timing is and at what rpm that the (total) timing stops advancing with and without vacuum advance. Then subtract your 10* initial timing from the total timing without vacuum advance which will tell you how much mechanical advance is built into your distributor. The numbers you posted are probably good for a turbo charged engine.

Sugar Bear

I don't know the answer to your specific question on that motor; however, consider confirming that the harmonic balancer is on zero when the #1 piston is exactly at TDC. If the balancer has slipped the ignition timing setting that is read on the scale will always be off by an amount equal to the balancer slippage.

Good luck!!!

jensenracing77

I did check that and good there. It is a temporary balancer because the original one is not back yet from having the new rubber put in it.

jensenracing77

Thanks. It will be another week or so before I fire it up again. I hope to have it back in the car Friday night but the car is not ready to fire it up yet. I done all this testing out of the car.

Fun71

Factory mechanical advance + initial advance is around 34 degrees, then vacuum advance added to that puts it at 44-54 degrees. So yours in in the correct range.

jensenracing77

Thanks, I will isolate the vacuum advance and test it again just to see where it is with just mechanical and initial.

BangScreech4-4-2

As noted, around 34° should be about right. You'll also want to make note of the RPM maximum value is reached at.

jensenracing77

Was messing with this more last night. I have the initial timing set at 7 and then with the vacuum unhooked I get 23 with the mechanical advance and then with the vacuum hooked up also I am getting a total of 45. It is running great right now but I am not ready to boost with it yet. No brakes on the car so my two test drives were nothing crazy and on my back road. When it is fully road worthy, I will play with it at 10 degrees initial and see how it does. Factory for the Jetfre was 10.

Thanks

oldcutlass

I would set it at 10 and go from there. Your posted numbers are not going to hurt anything.