I recently did a cam swap on my 69 383. went from a 284 to a 268. Car ran fine for a couple days and then it started running rough and the pcv valve is rattling like crazy. I checked for intake leak and found none. I checked vac. and got about 18 but it is not steady the needle shakes a lot. I tried moving the pcv hose from the front to the back of the carb and it seemed to geta little better but still surges. I have heard from friends and relatives that this is the best place to get good sound advice, so thank you in advance. Jim

Have you reset your timing and carb since the change?

Thanks stumpy, yes after initial break in the timing was adjusted and as for the carb, really didn't have to do much but adjust the idle. Like I said the strange thing was I drove it for a couple days before this started.

Is it sealing well into the valvecover?

I would continue to search for a vac leak. Possibly intake valley pan

Run a compression check

That thing got a hemi? Just Kiddin'. Check the hose and carb fitting for blockage. Also check the filtered cap on the other valve cover. If the vacuum gauge read a bouncy 18 a leak is likely, though it may come from the pcv. Try restricting the hose a bit until the rattle stops. If it all checks out try the suggestion at the end of this thread: https://board.moparts.org/ubbthreads/show...amp;Search=true
Say hi to Gail & the grandkids for me. Need to get down there for my parts and
Ron
P.S. if the link doesn't work do a search for "pcv valve"

Thanks I'll see what I can come up with and let you know. Ron ur parts are safe and FROZEN.

I had the fluttering PCV problem too. I think just too much air was going through it after my rebuild. I shoved a restrictor(an old 1/4" drive socket) into the rubber line by the carb and that cured it.