High crankcase pressure 440

Need some advice from the panel here!
Low comp 440, Hughes whiplash cam and springs, nice bores with cross pattern visible, haven’t taken the pistons out- trusted sellers words it was tight and healthy. First startup blew rear main seal. Second the valley pan and found the old pcv valve was shot. Had then problems getting the Mopar performance valve covers to seal.
On with a pair of stocks from the replaced 400” and a new pcv and valley pan. Pcv connected to 3/8” under carb, hose from the other side hanging loose. New startup. Adjusting new street Demon carb and setting ignition with vacuum gauge. Everything looking okay. Everything tight, no oil leaking anywhere.
First careful test ride and oil stick came out. Noticed some blueish smoke too.
Tied oilstick with zip tie but it snapped when I stepped on it. Runs like a king. New valley pan starts to blow up too...
Blowby from poorly sealing rings (or too big gap) or can I have missed something?

Last one I had a similar experience with was a pushed out head gasket into the valley pan area

blowby & a wrong/damaged/inop PCV will exacerbate it. Start with a leakdown. EDIT good point on the head gasket, I would do a compression test first.

That could be a reason! Have used steel gaskets to bump up compression a bit but couldn’t find copper spray

One could do a leakdown test but your post pretty much guarantees the outcome. There are several potential reasons why, only a tear down / inspection will pinpoint the cause(s).

My bet if it is not a head gasket is busted ring lands on cast pistons as it sounds like you are having crankcase explosions. Tear it down before you damage the bores. Never trust anyone that sells you an engine you can't hear run, even crate motors in a crate, I have learned the hard way and end up in a mess with my name trashed for finding the problem every time.

Just did a compression test. From 127 to 135 psi on all.
One odd notice is that all plugs on drivers side are black from soothe but all plugs on passengers side looks normal brownish
Weiand dual plane intake, tti headers, 2.5” exhaust, MSD distr w/ vacuum advance

A compression test can be misleading as it will not tell you what the rings are doing under load (Combustion).

Sounds like your issue is probably on left (drivers) side. A leak down test may help but it's only going to confirm what you already know. Its tear down time IMO

A compression test can be misleading as it will not tell you what the rings are doing under load (Combustion).

Sounds like your issue is probably on left (drivers) side. A leak down test may help but it's only going to confirm what you already know. Its tear down time IMO [/quote]

True on both points,but a leak down test will usually give you a direction and some issues are not visible to the naked eye & hopefully narrows the search!

Do the testing first (comp/leakdown) THEN tear it down. Good record keeping/baseline will never steer you wrong/be a waste of time. Holler how it turns out.

You need to lean down the primaries on the side of the carb. that feed the dark colored plugs
It might be a simple as leaning out the idle air mixture screws on that side also
As far as excessive crankcase pressure that you have fixing the idle mixture won't fix that, sorry
Remove the PCV and the oil filler cap and revved the motor up once it is warmed up to operating temps and see how much blow by is coming out of the valve covers, if you can see a steady up push you need to identify and fix the mechanicall problems

On a dual plane intake the primary feeds two cylinders on each side.

On a single plane, they both feed all 8.

Only time I ever ran into all plugs on one side being "dark" was an intake leak.

Update:
Must have been a stuck piston ring. Now it runs normal. Did a few short test drives, very carefully to start with and then a few tire melters later crank case pressure suddenly seems to be normal.
It runs like a king 🤴 with the Hughes Whiplash cam! 💪
The 833 all the sudden feels very close ratio even with 3.23 😄
Will tune the carb and timing a little more and then new plugs.

There can still be a little issue with not perfectly sealing rings but now it’s summer so if it continues running like now I’ll dig into it later.

Thanks all for your support 🙏🤗

I ain't thinking from a stuck ring but if it stays good then you're good. keep us updated.