Thought I was making progress then problems again.

Cam on my 230.4 was shot and car ran like crap. Replaced cam and rockers and it ran pretty nice until it warms up. Finally figured out why.

Old cam was so worn the valves weren't opening all the way. With the new cam they do. Looks like it's pushing the part of the stem with buildup into the guide and they're hanging up. Of course then I lose compression.

Anyone have any suggestions short of pulling the exhaust manifold or head and scraping things down? Any additives out there that will help the exhaust? Lots for the intake.

There isn't a part to the guide that carbon from combustion would be forced through - if anything, it would keep them from closing all the way because the stem is open while the engine is exhausting the carbony gook, and then it has to close. It wouldn't be on the top of the stem from not having gone through the engine - any buildup would be oil sludge on the top end. And I HIGHLY doubt that'd be enough to keep your valves from closing.

It's far more likely a few of your valves are too tight when the engine's warm.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

I don't see how a new cam would affect the closing of a valve.
Weak springs *will* do it. They can be removed and checked/replaced without removing the head.

I see what you mean about buildup on the top end of the stem. Guess I was thinking backwards here!

I had done a compression check prior to changing the cam. It wasn't great but acceptable. After replacing the cam and running it a while it dropped the #2 cylinder. Compression was way down. Vac also is way down when #2 isn't firing so I must have a sticking valve.

It does fire on all 4 when it's cold. Once it warms up #2 is dead. Tried swapping the plug and wire with good ones too.

I did check the valve clearances when hot yesterday and it was still in spec. Even so I did loosen them up a few thousands to see if it made a difference but no improvement.

The old cam was worn about 1/8 inch on several lobes so the valves definitely were not opening all the way. No exaggeration either.

I can see how sludge might hold one open partially. Perhaps soaking it with marvel mystery oil might loosten it up.

If that doesn't work you may be able to clean them by using a string between the spring coils and polishing it.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.