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Discussion Starter · #1 ·
I have a 76 spider So far I have removed the air pump and revised the intake manifold to take deeper breaths. I also removed the exhaust manifold and pipes up to the center muffler ... Replacing this constricted mess with headers from a 72 spider leading to duel pipes to the center muffler
Any advice o. Engine timing with this new set up ? Also wondering if any mixture changes are suggested on the injection pump
Thanks much !
 

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I just did the same job on my exhaust system. Put in new/old headers from a pre'74 and a 2 into 1 front exhaust section. (The air-pump was gone when I bought the car.)

The car immediately started backfiring and running weird. I had to completely retune my SPICA. I don't know if this makes any sense at all, but it seems the newly reduced back pressure threw the whole thing off. Of course, in my case, a PO had installed a CAT on a Non-CAT car, so my back pressure was probably pretty significant.

I think the deal with timing is simply to set the advance as far as you can without causing backfiring or ruining your idle. On my car that seems to be just slightly past the M mark at +3500 rpm.

I don't know if earlier S2's had the M in different spot. Anyone?
 

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Yes, put it all back together until you get expert input. As bad as stuff like air pumps is, it is not straightforward to get rid of it and actually improve performance.
 
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