I put on a set of Mopar Micky Thompson valve covers on my '75 B100 and now it's idling rough. I think it has to do with the PCV valve because if you touch it a bit it'll actually die out. I'm not understanding what is now different, because my van ran great with the stocker covers. The vacuum hose is good. I have no problem putting the OEM ones back on really, I'd just like to know what happened, lol. The MT's have a small "dish" or oil splash shield on the inside to keep oil from vacumming into the carb, I wonder if it's an air-volume deal? Thoughts appreciated!

Hi Jason,

Well that's a good one. I'd also be tempted to reinstall the stock covers, but I sure would be curious as to the effect on the PVC flow.

PCV valve blocked by contact with the baffle? Check for vacuum at the Breather opening on the opposite valve cover? A slip of paper should be gently drawn onto the opening by vacuum.


I just went through an Idle situation on my TBI 318 '88 B250 Had to learn a lot and read up on that part.

Maybe a shorter valve body on the PVC if so ? Could be that easy.

Good Wrenching and Van On 318's!

Interesting. What happens if you pull the PCV valve and put your finger over the end if it while the engine is running?

I'm gonna look at some vacuum diagrams. A leak? Might could take some Vacuum readings, There's two kinds I found out.
I love a good Mystery...