TrimDrip

Seafoam works good in oil.

Unless you you think it is piston slap, I would think it would be a lifter collapsing or a loose rocker.

Run the Seafoam then readjust the rockers. If you take the rockers off the number one piston and the pushrods are not level when they should be, you may need a set of lifters.

may want to try a heavier weight oil next time too.

Creetan

Seafoamed it and put 10w40 oil in it this time with Lucas Stabilizer. Going to put the Tstat back in tomorrow and see what happens.

raftdaddy

to check an oiling issue with #1 cyl can you not just pour oil in the spout while it is running?should just pour right on your valvetrain

MADMAC

It's just a lifter!!!!!! When it warms up as stated by Tony and A_peguin, it gets louder. Lifters are just a hydraulic cylinders. When they start to wear out they will get noisey, the warmer the engine and oil the less internal pressure they are going to hold. Even if you adjust it you are going to have the same problem. Some go sooner than others. Make sure oil is getting to it through the galleys to fill the lifter also.

If your pour COLD oil into a warm lifter, it will quiet it down for a little bit.