390 compression specs,psi ?
Thread Starter
|
Senior User
Joined: Feb 2002
Posts: 465
Likes: 0
390 compression specs,psi ?
I did a comp test which went like this on a stock 390 2bll
passenger side front to back,125,125,85,120.drivers side
125,125,110,115, I think thats the order,whats the
actual compression cause my buddys car gets 165's and
his car runs 8.6 to 1, I have 8.5 to 1 so they should be
bout the same right? How much compresion can I lose before
needing to rebuild it? It still does the 1/4 mile in 16 seoconds
flat
390's are where it's at!!
Dory
passenger side front to back,125,125,85,120.drivers side
125,125,110,115, I think thats the order,whats the
actual compression cause my buddys car gets 165's and
his car runs 8.6 to 1, I have 8.5 to 1 so they should be
bout the same right? How much compresion can I lose before
needing to rebuild it? It still does the 1/4 mile in 16 seoconds
flat
390's are where it's at!!
Dory
Freshman User
Joined: May 2002
Posts: 36
Likes: 0
From: BOULDER CITY USA
390 compression specs,psi ?
I'm not shure on exact spec's, but with that 85 in there you should check out the problem. I was down to 48lbs in #6 cyl. and found that I had sucked a valva about 1/8in into the head. I still had great get-up-n-go just a really bad miss. Not sure if I'm actually helping you but just thougt I'd let you know. Good luck.
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
390 compression specs,psi ?
It might be an exhaust valve, does it miss or lope at idle?
Other than that, your compression is ok but low. I wouldn't start worrying about a rebuild until it goes below the century mark.
But then we don't know what's wrong with that low cylinder.
Barry
Other than that, your compression is ok but low. I wouldn't start worrying about a rebuild until it goes below the century mark.
But then we don't know what's wrong with that low cylinder.
Barry
Thread
Thread Starter
Forum
Replies
Last Post
406angler
1973 - 1979 F-100 & Larger F-Series Trucks
5
Jul 23, 2017 08:38 PM
TruckerATK
1957 - 1960 F100 & Larger F-Series Trucks
3
Oct 4, 2016 04:31 PM
Randoo
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
2
Jun 19, 2003 10:42 AM
