timing difference for 1500 for different years?

[recordsj]

I have a california spec 1500 mg midget engine (FP17095UCE), don't know what year it is though. The smog equipment has been removed. Has Weber 32/36 DGV carb, pertronix electronic iginition.

From the Haynes manual it says the following for igition timing:
1500, except USA: 10deg BTDC @ 680 RPM
1500, '75-78, USA: 2deg ATDC @ 800 RPM
1500, '78 and on, USA & Canada: 10deg BTDC @ 800 rpm
1500, '78 and on, California: 2deg ATDC @ 800 rpm

Why the different timing specs for this size of engine? How do I konw which one I should follow?

 

[tosoutherncars]

J, start at about 12BTDC to get it running, and go from there. Just advance it until you get slight pinking going uphill in fourth, then retard a couple of degrees from there. Yes, the DGV requires more advance than stock, and the stock numbers are conservative to start with.

 

[recordsj]

that really doesn't answer why the timing specs are different. Does it have anythign to do with when the smog equipment is attached?

 

[startech47]

The timing is set at idle. The distributors probably have different mechanical and vacuum advance curves and might have different amounts of total advance. This would require different amounts of idle timing to achieve the same total advance.

 

[tosoutherncars]

Yes, smog equipment, different distributors, different emissions requirements.

Really, I was trying to answer "How do I know which one I should follow?" The answer is, none of them... None are specs for a de-smogged low-compression engine with a Cali-spec distributor and a progressive carb that requires more advance.

A couple of us have setups the same as, or setups very similar to you. Mine is a desmogged Cali 1500 with a DGV. Closest thing I can give you to a spec is approx. 10 deg. @ 800RPM. Should get you close, and you can fine-tune from there!

Let us know how it goes...

 

[recordsj]

thanks for the info, I figured that was why there are difference.