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Engine timing

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Bob Buxbaum

Jedi Hopeful
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So, fully rebuilt 1976 1500 with a full complement of factory emission control garbage attached. The owner wants it stone stock. Factory time is 2 degree ATDC at idle. The engine starts instantly, idles beautify, and has the power band of an old tractor. The owner says that is how it has always felt.

Question -- can I SAFELY bump the timing a few degrees BTC to give a bit of help?
 
Does it have the original distributor and vacuum advance module?
 
At some point they were doing some crazy stuff with the timing for the sake of emissions. IIRC, it was required to keep the stock timing to work with the emissions stuff otherwise you'd get incomplete burn at idle.
 
Trevor Jessie said:
At some point they were doing some crazy stuff with the timing for the sake of emissions. IIRC, it was required to keep the stock timing to work with the emissions stuff otherwise you'd get incomplete burn at idle.
Click to expand...

I am well aware of the emissions issues. The question still stands -- can I SAFELY bump the timing a few degrees BTC to give a bit of help?
 
I do not know the answer. I suspect that bumping the timing might give it a bit of help, but at the risk of damaging the cat or over heating the cat. The 1500 engines have a pretty long stroke and I've always thought of them as just a low rpm high torque engine.
 
Trevor Jessie said:
I do not know the answer. I suspect that bumping the timing might give it a bit of help, but at the risk of damaging the cat or over heating the cat. The 1500 engines have a pretty long stroke and I've always thought of them as just a low rpm high torque engine.
Click to expand...


Umm .... no cat. Not a California car.
 
Only the 1975 cars did not have catalytic converters. My parts book puts the cut off at GAN6-166304

Does it have EGR valve still in place? What about the anti- run on valve? If those are missing, or are not working, then you are going to need to just tune old school and hope for the best.
 
I run my 75 Spitfire at 12 degrees before TDC. With a pertronix module. It also has HS 2’s. And it runs great. It’s the same motor. If you are too far advanced you will get pinging under heavy load. Then you will need to back it off a little.
 
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