Hey there

I got my first comp gauge, so I decided to do a comp test since I've been having funny problems. First of all I have to say that I purchased a taiwanese gauge (oh, yeah, I'm cheap) in my defense the only thing I can claim is that piece of junk wa the only thing I could find down here.

Well, I removed all the spar plugs, the coil to dist cap wire and started working. Engine was hot like for setting valvle lash. cyl 1 was 98 PSI, #2 was 110 PSI, #3 was 95 PSI, #4 was 100 PSI, #5 was 115 PSI, #6 105 PSI. SO I went nuts and decided to do a wet test. #1 100psi #2 110 psi #3 100 psi #4 105 psi #5 120 psi #6 105 psi. I'm looking over blown head gasket and r burnt valvles am I? I ended up so upset that I retorqued the head to 11kg, with minor changes when remeasured.

When I finished my mill it had around 160 psi, give or take a few pounds, but I didn't measured those #'s with my ne gauge.

No oil leaks, no coolant leaks, no mixed fluids, sometimes I get a gas smell coming from the engine and it ain't carb or stuff like that. I do have a li'l bit more oil consumption, but I moved to synt 5W40 oil in my last change. I do have some come and go overheating problems (not major problems but still are there)

Any words?

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Hmmm, that's a big drop, and across all cyls... Possibly the gauge is wrong, or the original gauge was wrong?

A common reason for low comp readings is tight valves, but that is usually different for every cyl. Adjust lash?

New cam? Stretched T chain?

They are consistent, so you are looking at a symmetric problem (same for all cyls). Head gasket wouldn't do it, and burnt valves show up one or a few at a time...

Lou

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Home of Slant6-powered fun machines since 1988

I would either take the gauge back and get another one to see if it's different or get someone with a known good gauge to measure. Where was the 160 reading from? Could you get a reading from whoever took that reading?

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64 Valiant

Aha!

Thanks guys, I almost go nuts on this

History goes like that. I got a new cam when I put together my fresh mill, and grinder said to set .08 ex and intake. While I was breaking in the new motor, I loose taht lash like .10 on intake and .18 on ex. This was when I got my first 160 psi (give or take) reading. I wasn't happy with my grinder's specs about lash so I experimented everything, from zero lash to .20 .20 lash. I don't know wich pattern he used, but this cam likes very much low lash settings. Currently I'm .05 .08 and it works great but I suppose I have that to blame on my huge comp drop. I haven't got 2 even #'s on my cyls so I guess that I'm to due my apparent compression drop to that tight lash.

I'm gonna loose those valvles and see if i see some PSI raise.

thanks.
Juan

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.