Thread: timing - it PINGS !

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Mike,
Pat asked about the gas. Is your 91 octane fuel an ethanol blend or straight gasoline? An ethanol blend will start phase seperation within two weeks of storage, and as it seperates you will lose 5 to 6 points (or more) on octane rating - your 91 will actually be 85 or 86. Are you using a good dial back digital timing light, where you can set your rpm at say 3500, and dial it back until your timing mark zero's out on the dampner to pointer? If so you should be saying, "It's running 36 degrees total timing", not "...timings running about 36 and it's still pining." If you have a good dial back light, run your rpm's up until the timing stops advancing, and dial it back to see what the actual value is for your engine. Rotor position (which tooth you hit on the cam) is only important if the adjustment of the distributor base is restricted in some way, or if your plug wires are too short to allow the base to be adjusted to compensate for the rotor/cam position. You can be 180 degrees out, and as long as you can spin the distributor base 180 degrees you can set your timing accurately. It may look goofy, but it does not really matter in the way it functions.

If you have good gas and know that the timing pointer & TDC mark were properly aligned during the build then I would start backing off the total timing a degree at a time until it quits detonating. Once there, check the timing at idle & no vaccum advance to see where you are. Depending on what you find you may need to re-work the timing curve with springs & stops like Pat & Jerry mentioned. If you don't have a good, digital dial back timing light then you need to either buy one, or find a friend who has one and knows how to use it. To me 36 degrees total timing is not a high number for the engine you describe. Old, phase seperating ethanol blend gas that's been in your tank for weeks/months is a really good possibility here, IMO. Let us know what you find.

Well - I might know where I'm going wrong now. I am using Shell 91 octane
gas. It seems to run the best, but the method, I set the timing, - - probably
isn't the right way, as you explain above. I'll try running the rpm's up, and then
set it, and see what happens.