I have a 77 280Z that I recently adjusted the valves on, Hot - I -.10, E .12. Seems to run OK but I have what sounds like a miss (puff-puff) at the exhaust. The only problem is that I found out the the head is a P-79 off of a 81-83 ZX. My question is, I think I know the answer, shouldn't I adjust the valves to the ZX settings, Hot I .25, E .30. Thanks

I am fairly certain that all the L engines (mayby not 83 P90a hydraulic) have

0.010/0.012 inch cold and 0.008/0.010 inch hot valve lash specs.

Checked the 82 AND 71 FSM

You are likely just getting the mm and inches specs confused. Common mistake.

Remember that setting the cold spec is just to get close, but after running it up to temperature, set them to the hot spec to get them right.

Jim

.10/.12 inch is hot. Cold values are .08/.10 inch.

Could be dirty/sticky valves.

I have a 77 280Z that I recently adjusted the valves on, Hot - I -.10, E .12. Seems to run OK but I have what sounds like a miss (puff-puff) at the exhaust.

The 10 12 is correct . the puff -puff could varywell be a burned valve. check the compression.