engine diagnosis 101
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Pro
Joined: May 2006
Posts: 583
Likes: 0
From: Pittsburgh PA
engine diagnosis 101
1977 with 100K on the meter. Starts and runs fine, no misses at any of the RPM range. When running after warm up it begins to smoke lightly, not generally the some you see with bad rings. What do you think? The engine is coming out for a rebuild but I am courious as to the cause of the smoke. Thanks for the input, Jack
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Before you pull it, do a leak down test and a good compression check. The leak down will tell you if there's any leaking past the rings (with 100k I'd expect some) and also you can listen at the intake and exhaust for possible valve problems. Again at 100k, I'd expect valve guides to be worn and the seats in fair shape. But as you said, it's running fine, just some smoke. I'll guess it's blue (oil) so I'd be back to rings and valve guides.
Unless you're looking to stay with the original block/heads, you might check prices on crate engines compared to rebuilding your engine. Lately, the prices have gotten real competitive
Unless you're looking to stay with the original block/heads, you might check prices on crate engines compared to rebuilding your engine. Lately, the prices have gotten real competitive
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
Depends on the color of the smoke and if on accel or decel.
Generally
Blue= oil burning
Black= too much fuel for the air/rich
White= water/coolant being burned/injected
100k does point to blue smoke and rings and or valve seals.
Get a plan before you rebuild.
It is safe to count on a bore job.
Valve job
maybe a crank grind.
Get an idea of what you are after in the build.
find a reputable machine shop.
You will have to decide between long life or long power.
A compromise can get you a strong pulling trouble free build.
Generally
Blue= oil burning
Black= too much fuel for the air/rich
White= water/coolant being burned/injected
100k does point to blue smoke and rings and or valve seals.
Get a plan before you rebuild.
It is safe to count on a bore job.
Valve job
maybe a crank grind.
Get an idea of what you are after in the build.
find a reputable machine shop.
You will have to decide between long life or long power.
A compromise can get you a strong pulling trouble free build.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
