Hi

Why is it so difficult to find the information concerning the right spark plugs for my olds 307 (1980 with 5A head). There is no information in the service manual !

I looked at the forum, I found nothing very sure.

Can anyone confirm me which sparks I may use ?

Is it the R46SX ?

Thanks a lot that will help me a lot.

 

The information is on the emissions sticker under the hood. Since there were variations for engine options and 49-state vs Calif, it was easier to just put it on the decal.

 

You probably want R46SZ (GM p/n 5613882), which is the substitute GM recommended for the R46SX (GM p/n 5613881) circa 1986. The SX comes preset with an 0.080" gap, while the SZ comes with an 0.060" gap. This was due to the wide gap putting too much strain on the ignition module and causing early failures that GM had to fix under warranty. Shortening the gap seemed to fix the issue and still not hurt the performance.

You could always regap an SX, but that's up to you. Regardless, I'd ditch the 0.080" gap and go with 0.050-0.060" plus or minus.

 

Hi

Thank you so much for your help. The reason I could not get the info on the emission sticker is the engine is in a cadillac (swap).

I will buy a set of R46SZ.

All the best.