Compression Test.....Pressures ??
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,473
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From: Clearwater Florida
Compression Test.....Pressures ??
OK...With all the spark plugs out , cranking pressures with a five count on the compression strokes should be ??? Spec-wise , the car is an 87 with a 409 inch motor , -14cc dished forged pistons , 58cc heads , approx 11:1 compression , Comp Cams XE268-14...duration @ .050 is 224 in....230 ex....114 LSA ....I'm seeing 235-245#..... is that high ??? The engine is clean inside....carbon build-up-wise........
Corvette Enthusiast
Joined: Oct 2007
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From: So. Cal.
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C. Test
I have always used the 10 % rule. All cylinders sould be within 10% of each other.
Melting Slicks
Joined: May 2001
Posts: 3,014
Likes: 18
From: Raleigh, NC
235-245 isn't bad. A stock 350 out of an old truck or something would likely be around 125 per hole, a 350 out of a mid year Camaro or other semi-performance oriented car might be around 175 or so. A really high performance set up for the street might be 300+.
I don't think you have anything to worry about there, as long as all the cylinders are within 20 PSI or so.
I don't think you have anything to worry about there, as long as all the cylinders are within 20 PSI or so.
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
A leak down test@ TDC is more accurate as I just went through this on C-2 forum as Jack did a compression test and it was 170 to 200 on his 327 was complaining of dirty oil in less then 100 miles and this engine had 400 miles on it since it was rebuilt and after we did a leak down test the best cylinder was 10% and the worst was 35% leak down and the average was 18% leak down.
Here is the link
http://forums.corvetteforum.com/c1-a...blem-saga.html
Here is the link
http://forums.corvetteforum.com/c1-a...blem-saga.html
Last edited by BLOCKMAN; May 10, 2009 at 12:24 PM.
