This is a weird one. I know I am gonna feel stupid when I get the answer.

1979 RX7 12A

Points in the distributor.

The previous owner had locked down the timing advance plate and removed the vacuum pots for the leading and the trailing advance. The car was stumbling so I got pots off a salvage car and installed them. It fixed the problem and all was well until I installed an exhaust header about a month later. Now it’s all jacked up. The stumbling came back.

Checked the timing and its way off. The leading spark, that should be on the white mark (TDC), is past the trailing mark (red mark). I have the distributor turned as far clockwise as the slot will allow and it’s still not even at the trailing mark.

I guess I can pull the distributor out and rotate it one tooth but how could putting and exhaust header on cause this? Something else is going on.

Oh I also did the “removing the rats nest” thing but even with the vacuum advance lined removed I can’t adjust the timing even close to where it needs to be.

HELP PLEASE

 

I honesty have no idea why exhaust work would alter your timing. However I can say from experience that the points style distributor on SA's can be finicky at times. I had issues with one drifting timing, not to your extreme, and after a week or two of confusion I swapped over to the electronic style off of the FB's and never had another problem. There are several write ups on here as to what needs to be changed if you decide to go that route. Sorry I cant be more helpful.

 

If you put a header on an fb that I'm assuming you removed the emmisions and used the block off plates? Check the gasket seal at the plates with some starting fluid. Spray some around the block off plates and listen for idle changes. If it changes take them off and use some mr. Gasket or rtv or something of the sort to make a tight seal between the plate and the intake. This happened to me once in my 80' sa when I put my header on.