390 Stuck Valve, need help!!!!
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Run the compression test again, this time do a 'wet test'. Pull all eight plugs, block the throttle open (you did that on your first test, right?), then before you test each cylinder, squirt a couple of teaspoons of oil in the cylinder.
If the compression comes up a significant amount then more than likely the problem is the rings. If it still has no compression then it's either a valve problem or head gasket.
If there really is "0" compression on #7 I would bet that it's valve related. Usually if its a head gasket or ring related, there would be some compression.
Just because it's never run hot, it could still be a valve. Running hot can make a valve seize in the open position. But, seeing as yours is a '69, unleaded fuel could have caused the exhaust valve seat to recess or a chunk of carbon could be on the seat keeping the valve from sealing or a valve could be burned.
If it is a valve problem, now would be the time to pull the heads and have them upgraded for unleaded fuel. Have stainless steel exhaust valves and hard steel exhaust seats installed.
Mountain Pass
Joined: Mar 2014
Posts: 104
Likes: 1
From: Southeast AZ
Bronze valve guides/sleeves??
I've had a few experiences with stuck valves/bent push rods on FE's. Haven't done any of these for quite a few years. Back in old days- cheap was to knurl guides when doing valve job- bad choice- stuck valves/bent push rods.
Better to ream guide & press in bronze guides, but here again, make sure machinist understands proper interference press/fit and guide ream. Good luck...john
Better to ream guide & press in bronze guides, but here again, make sure machinist understands proper interference press/fit and guide ream. Good luck...john
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
If you have your heads rebuilt, a good source for the stainless steel exhaust valves is SI Valves in LA.
SI VALVES- ANTIQUE/VINTAGE ONLINE CATALOG
I used them when I had my heads rebuilt. They also have an intake valve they call the "seat saver". It's head is +.030" oversize for engines that have had multiple valve jobs.
Eight stainless steel exhaust and eight Seat Saver intake valves, including shipping ran me around $80.00 for my 390.
SI also has valve seats but my machine shop wanted to furnish the seats to be sure the cutters they use were compatible.
SI VALVES- ANTIQUE/VINTAGE ONLINE CATALOG
I used them when I had my heads rebuilt. They also have an intake valve they call the "seat saver". It's head is +.030" oversize for engines that have had multiple valve jobs.
Eight stainless steel exhaust and eight Seat Saver intake valves, including shipping ran me around $80.00 for my 390.
SI also has valve seats but my machine shop wanted to furnish the seats to be sure the cutters they use were compatible.
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