Blueyata

Hello! I’ve been having a weird noise come from my engine on cold start. It has been there ever since the first startup. It sounds like it’s either coming from the head or headers and can be heard through the exhaust until the car is warm. When it’s at operating temperature it completely goes away. It sounds like a loud tick or rattle and cannot really be heard over 3k Rpm’s.

Engine:
supertech 9.5.1 pistons with wiseco rings
eagle rods
king bearings
stock vvt head
boundary oil pump
fluid damper
arp main studs
fab 9 head studs

rotrex c30-94 running 17psi

Made a little over 250whp on 93 with conservative timing

All the work was done by a reputable machine shop and the engine was completely disassembled and cleaned. Valve lash was checked and was in spec (as far as I know).

compression numbers (warm):

cyl 1: 197
cyl 2: 190
cyl 3: 190
cyl 4: 206

I find it strange that cylinder 4 is so much higher than cyl 2 and 3, but the machine shop said it should be fine. I’m guessing this is probably due to the valve lash on cyl 4 being off and maybe they did not check it?

Maybe this is a header leak? No metal was found in the oil other than the normal break-in material in oil.

Here is a video of what I’m experiencing: