cam bearings
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Junior User
Joined: Jan 2004
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From: colorado
cam bearings
Hey all, attempting my first engine rebuild on my 360. The only thing that was really worn (besides the heads and exhuast valves) were the cam bearings. They were really torn up.
Does anyone know why this happens? I'm thinking about doing the oil modification you all mention, but I'm planning on a stock rebuild so I'm not gonna run high rpms. Would getting more oil to the cam bearings keep this from happening?
Does anyone know why this happens? I'm thinking about doing the oil modification you all mention, but I'm planning on a stock rebuild so I'm not gonna run high rpms. Would getting more oil to the cam bearings keep this from happening?
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From: Long Island USA
What you were seeing was most likely loss of oil pressure from worn rockers and rocker shafts.
The mains and rods will get oil first, then the cam bearings second. Once you lose oil pressure from the rocker shafts, the cam bearings will certainly get a bit cooked and if you had a lot of slop in the top end, that was banging the cam around pretty good.
Replace the rockers and shafts, restrict the oil hole in the heads, and you should be good to go for a long time.
Also, who knows what really happened over time with that engine. It could have been starved for oil once, or twice
The mains and rods will get oil first, then the cam bearings second. Once you lose oil pressure from the rocker shafts, the cam bearings will certainly get a bit cooked and if you had a lot of slop in the top end, that was banging the cam around pretty good.
Replace the rockers and shafts, restrict the oil hole in the heads, and you should be good to go for a long time.
Also, who knows what really happened over time with that engine. It could have been starved for oil once, or twice
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From: Long Island USA
Argess, you are absolutely correct. I just checked an oiling diagram for the FE, and the oil goes from the oil filter to the front main bearing and front cam bearing, then to the lifters, which then feed the rest of the cam bearings and mains (and from there to the rods).
The number 2 and 4 cam bearings feed the rocker shafts.
To the original poster: What cam bearings were the worst? Or were they all the same?
The number 2 and 4 cam bearings feed the rocker shafts.
To the original poster: What cam bearings were the worst? Or were they all the same?
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Junior User
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From: colorado
o.k, one thing's loud and clear. Change my oil! Although I'm pretty diligent about that, there are times where it slips...
Actually, I just thought of something else, I've attempted my fare share of cold starts (-10) on the engine. It never had a block heater. Could starting it up in the cold rip through the bearings as well?
I will have to look tonight to tell you which ones were worst. I should probably also check to make sure that the holes in the bearings line up with the oiling holes. I've been spraying wd-40 in the passages to see where they go
As far as the oil modifications go, is it still a good idea for a stock rebuild?
Much thanks in advance
Actually, I just thought of something else, I've attempted my fare share of cold starts (-10) on the engine. It never had a block heater. Could starting it up in the cold rip through the bearings as well?
I will have to look tonight to tell you which ones were worst. I should probably also check to make sure that the holes in the bearings line up with the oiling holes. I've been spraying wd-40 in the passages to see where they go
As far as the oil modifications go, is it still a good idea for a stock rebuild?
Much thanks in advance
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 421
From: Long Island USA
The mods won't hurt anything, but the cost might be a bit much for a stock build. I'd at least restrict the rocker arms oil feed.
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From: colorado
I was planning on doing the drilling myself, the cost would be the high volume oil pump. Would I even need that?
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Anti-freeze can also take out bearings (leaking head gasket, etc.), but generally the last rod bearing will be the first to go (lowest oil pressure), not the cam bearings.
I always warm up my engine gently for a while....under load, but not high revs. Oil filters have a bypass in them (in case they get clogged), and everything will be sent to the oil galleries if you rev it cold. But the bypass also opens when the oil is cold and thick.
Drain oil when warmed up as it keeps particles suspended in the freshly agitated oil and they come out the drain.
Just speculation, but I'd say metal or carbon particles would drop out of the oil early and be a problem in the cam, crank or rod bearings in order front back.
I always warm up my engine gently for a while....under load, but not high revs. Oil filters have a bypass in them (in case they get clogged), and everything will be sent to the oil galleries if you rev it cold. But the bypass also opens when the oil is cold and thick.
Drain oil when warmed up as it keeps particles suspended in the freshly agitated oil and they come out the drain.
Just speculation, but I'd say metal or carbon particles would drop out of the oil early and be a problem in the cam, crank or rod bearings in order front back.
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Junior User
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From: colorado
update
Well, was trying to install the new cam and I think I might have found out why the bearings were destroyed.
The #2 cam bearing bore seems to be out of round. The cam will not fit in the second hole. We took the bearings back out, and put a straight edge, and it rocks slightly in just about a 30 degree section of that one hole!
Has anyone seen this before? It seems to be a day one defect, as there are no apparent marks on the block. Probably the previous builder just crammed the cam in there....
The #2 cam bearing bore seems to be out of round. The cam will not fit in the second hole. We took the bearings back out, and put a straight edge, and it rocks slightly in just about a 30 degree section of that one hole!
Has anyone seen this before? It seems to be a day one defect, as there are no apparent marks on the block. Probably the previous builder just crammed the cam in there....
