So. Questions for the engine gurus. I have a 302. Had it built ahh about 15 years ago. It started in my bronco when I was mud racing in Wisconsin. Then into two different ice racing cars then a 1980 and 1984 tough truck bronco. So it has lived it's life at 6000rpms +++. Long story longer. It's been back in my bronco for 5 yrs or so running like day 1. I just put a PCV system on it and after cleaning it up changing oil and stuff I took a measurement of some header temps to make sure all were firing and hot. Well two cyl are about 1/2 as hot as the others. Funny thing is if I pull the PCV and plug the line the temps instantly rise. Can the PCV be pulling the mixture away from the cyl or something? I need to do a compression test yet but maybe rings are shot. Any ideas? Valves are adjusted and moving. Just weird that a PCV would cool the temps of only two cyl down. One on each side of engine.

Could be. Is the vacuum port common to those two cylinders and further from the others? Best place for PCV vacuum is at the carb base for even distribution.

It's #4 and #7. I put it directly into the intake. Maybe too much vacuum. I changed it to the air filter housing and everything is as should be. Have to go beat on it to see I guess.

My prev PCV was pulling from the carb spacer, then the other side vented to the air cleaner housing, set up from the factory.