Your donations help keep this valuable resource free and growing. Thank you.
|
Intake valve stuck - increase performance? |
Post Reply | Page <1 234 |
Author | |
Archangeldvm
AMC Apprentice Joined: May/13/2021 Location: Ventura Status: Offline Points: 51 |
Post Options
Thanks(0)
|
Was checking the rockers and stuff for uneven wear and found something interesting. When bolting the rockers back on I pushed down on rocker over the intake pushrod. It went down and sprang back up. No other intake rocker over a pushrod does this.
I assume the rod springing back is from the spring in the lifter? Does this mean the problem is the camshaft love? Thanks for thoughts.
|
|
BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1713 |
Post Options
Thanks(0)
|
my guess is the lifter that springs back is leaking down where the others are not. but just a guess. If you get to the point where you get the intake off, and pull the lifters out make sure you keep track of them so you can put them back in the same location. Lifters start out slightly convex on the bottom. If you put two together bottom to bottom you can see the daylight at the edge. A lifter that is concave, maybe looks like a smaller circle recessed in the lifter face, is ruined. The cam lobe it was on is ruined. I'm not telling you to expect that, just telling you what to look for. If you have a worn out cam and lifters you won't be the first guy. the additives that protect these parts were removed from the oil to reduce exhaust emissions. dumb, huh?
|
|
Archangeldvm
AMC Apprentice Joined: May/13/2021 Location: Ventura Status: Offline Points: 51 |
Post Options
Thanks(0)
|
Thanks for reply and information. I will check them, or mechanic will, and see what problems I have. I have not had the car that long but I do know the previous owner was not using the higher zinc oil
|
|
Archangeldvm
AMC Apprentice Joined: May/13/2021 Location: Ventura Status: Offline Points: 51 |
Post Options
Thanks(0)
|
Update as requested. Finally took off intake (my first time) and found the problem.... Photos below.
Questions What would do this Looked at cam lobe and looks worn but wonder where all the lifter metal went to? What's next you all????? |
|
Archangeldvm
AMC Apprentice Joined: May/13/2021 Location: Ventura Status: Offline Points: 51 |
Post Options
Thanks(0)
|
Photo 2
|
|
1BadJav
AMC Nut Joined: Mar/07/2008 Location: Las Vegas, NV Status: Offline Points: 342 |
Post Options
Thanks(0)
|
Chevy had a problem with late 70s/early 80s 305 motors wearing the lifters and cam lobes. I replaced more than a few of those. I think the cause was inferior metal used to make the cam/lifters, but, don't remember exactly. It usually happened on the number 6 cylinder. Could have been an oiling issue as well. Could be a similar cause in your case.
Edited by 1BadJav - Aug/27/2021 at 6:34pm |
|
72 AMC Javelin SST - 401/727
|
|
Monk Daveohue
AMC Apprentice Joined: Aug/13/2020 Location: Southern Calif Status: Offline Points: 76 |
Post Options
Thanks(0)
|
What could cause it? Just lots of miles. 100,000 miles or more can cause it. What Next? New cam and lifters. Well, in order, pull: Radiator shroud, fan, radiator, power steering pump, alternator, fuel pump, pulley, vibration damper, timing cover, timing set, intake manifold, lifters, camshaft. At this point, I wouldn't bother trying to record which lifter came from which location. Actually I had lifters worn concave like that, but not nearly as bad, on a 440 Chrysler. Not all the cam lobes were bad. But a couple were worn down. If it weren't for those lobes I probably could have used the re used the old cam and just changed the lifters. They say never put old lifters on a new cam but you can sometimes use new lifters on an old cam if the lobes are still convex. I'd run a compression and leak down test on the remaining cylinders. If it has that much wear on the cam lobes the whole engine may be worn out.
Edited by Monk Daveohue - Aug/28/2021 at 4:25am |
|
JERSEYJOE
AMC Addicted Joined: Oct/23/2008 Location: TUG HILL NY Status: Offline Points: 1718 |
Post Options
Thanks(0)
|
With the bottom of the lifter worn like that I would say with 98% certainty that the camshaft itself is also worn to the point that the lobe lift is effectively zero. Excellent advice to pay someone to do a cylinder leak down test to assess the quality of the ring seal. If this test shows low leak down than I would install a new camshaft and lifters.
|
|
1985 J-20 PLOW TRUCK
1977 CJ 7 360 T-18 D 300 1970 AMX ex-SCCA car SPEED COSTS MONEY HOW FAST DO YOU WANT TO GO? |
|
BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1713 |
Post Options
Thanks(0)
|
Sadly you are going to have to replace the cam and lifters. You are right to ask the question "where did all that metal go?". That said I have an engine that had the same problem, hole in the bottom of the lifter and I did tear it down and the crank was fine. Fram filter must have done its job. No trash in the pan. Have not torn the oil pump apart but it stiill had oil pressure when it was trying to run. I know of one shop that trashed a customers cam because they didn't break it in properly. They bought a pre broken in cam and lifters and put it in and sent the customer on his way. So you wouldn't be the first to put a cam and lifters in and take your chances. There are lots of things that can cause that cam and lifter failure. You already mentioned oil without zinc. There was a bad batch of cams years ago. There were problems with the supply of lifters for years, and the "gummint" edict to take zinc out of passenger car oil to improve catalytic converter life really hurt those of us with old cars. Sorry.
|
|
Post Reply | Page <1 234 |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |