cant figure it out
Thread Starter
|
New User
Joined: Sep 2004
Posts: 5
Likes: 0
cant figure it out
iv got a 351m 40 over it had a blowen head gasket so i replaced both of them and intake,headers etc.. fired it up and test drove it ran pretty good the next day i went running around and the oil pressure dropped (dummy gaudge) it was running like crap then i heard a knocking it sounds like its coming from the front of the motor we turned the crank and watched the rotor before it was fired it didnt seem to be streched any advice what range should the compression be when runing a test? thanks for any help
Freshman User
Joined: Aug 2004
Posts: 29
Likes: 0
when i tested the compression #1 cyclinder was 100 psi the next one was only 80 psi that was cold.. the truck sat outside im 35degree weather then i warmed it up and it got worse #1 dropped to 85 psi and the next was 65 psi im not to shure how good the tester is i am going to get a new one tomarrow and check it again after that i am going to pull off the timeing chain cover and look that over but after i get those chores done i will let ya know how it goes
Posting Guru
Joined: Dec 2002
Posts: 2,003
Likes: 2
From: chicago burbs
make sure you have the throttle held open during testing. to avoid flooding the engine, just wedge a screwdriver in the linkage somewhere. this allows the cylinders to get all the air they want to compress for the test. take all the plugs out before you start too, this will allow the engine to spin more freely and not pull down your battery and starter so much. if you only had 80psi in each hole it would be OK, not real good but OK. what's bad is when there is a big difference between the highest and lowest.
Thread
Thread Starter
Forum
Replies
Last Post
Countryboy1973
1987 - 1996 F150 & Larger F-Series Trucks
9
Sep 23, 2020 02:32 PM
mdsnjames
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
3
Jul 22, 2015 09:15 PM
Wiley
1948 - 1956 F1, F100 & Larger F-Series Trucks
2
Jul 29, 2003 06:51 AM
