For those who happen to read this and don't know, my builds are new this year. So the port engine has been down on power for a little while by 200 rpm or so. Possibly from the get-go but really don't remember. I always lift the hatch when starting to make sure there's not a leak or a problem and just generally look around. The old exhaust tips had metal internal flaps and made a ton of noise so I couldn't hear the lifter making noise. Switched them out for straight through tips with rubber internal flaps and now I can hear it. It's a comp hydraulic roller cam and I have roller rockers too. Is there a way to find out if a lifter is failing? The lifters were pretty tall. I believe that they (comp) switched to this style because they will work in many applications? FYI oil pressure is always great on both engines. I am using the AFR 265cc heads out of the box. The clearances from AFR are on the tight side for marine use according to the guys on this site. Can a push rod hanging up do this or do tight guide clearances just cause a catastrophic failure? I am hoping that maybe it was not adjusted correctly when assembled? I doubt this is the problem but a guy can hope. I will also call my builder and see what he thinks. I'll get the valve cover removed in the next few days. May have other questions after that. Thanks for your comments.

I have my doubts be a guide or plate but easiest thing to do IMO be pull the valve covers and ck your rockers for excessive play while rotating your engine. Ideally on the heel of the lobe but doesn’t have to be exact. Even ck at TDC and then rotate 360 deg and repeat. If you have a loose one you’ll quickly identify.

Regardless of outcome re-adjust lifters to spec and fire it up.

Just hope it’s not a lobe but kinda doubt it

You could also ck all the spark plugs for any noticeable color difference to help isolate which cylinder is causing the rpm loss and noise.

TIcking at idle or at RPM?

Both. I noticed it at first start up today on high idle. Still there at 800 rpm idle. Then took it to the ramp (about 10 minutes at 1000 rpm) and it was still there.

Not just exhaust leak or plug wire arcing?(Wishfull thinking)

What oil/weight?

Nope. They all make distinctive noises imo. My wishful thinking at this point is maybe the lock came loose on the rocker.

I had horrible luck with the new comp lifters and cams. I wouldn't be surprised if it was bad. The build quality now a days just isn't the same for lifters. If u pull a valve cover and find a loose rocker or a pushrod kicked out id be pulling the intake to check the cam. I ended up going to teague for there cams and lifters

Could pop valve covers….when idling push down on rockers individually. See if noise goes away.