[dbpontiac455firebird]

Hi all,
300ex no compression. Set to TBC — “T” in in the window, Cam lobs are down, stuck screwdriver in SP to confirm TDC, Piston was at the top. Test compression, zero. Put finger on sparkplug hole, I feel sucking, no pushing out. Put oil in the cylinder, retested, no compression. But oil came out exhaust port in the head where the header mounts. Seems odd to me. So though Id would post this before the tear it down and look around.

Thank you

 

[SlammedRanger]

Oil coming out exhaust ports is normal if you put a good amount in. Your only supposed to put like a syring of it at the most in. But if you did all that and have zero compression either you have a hole in the top of the piston. Or the headgasket is really blown bad. Only other possibility would be a bent valve but that would have made adjusting the valves near impossible. Welcome to the forums!

 

[dbpontiac455firebird]

Hi, thank you, great forum valves can be adjusted, So ill break down the top end inspect the parts. Thanks again.....

 

[SlammedRanger]

No problem always glad to help!