broken cam chain

[JasonRedbeard]

the only problem with that is that if both cams are still attached to the
head and u only turn 1 cam at a time u run the risk of bending more valves
as the cams arent being turned together at the same time.

So watch the lobes and don't turn an open valve across another open valve on the same cylinder.

It's rhetoric anyway though....the head will still have to come off at some point to replace whichever valves ARE bent. Might as well just yank it off and look.

[cywelchjr]

the only problem with that is that if both cams are still attached to the
head and u only turn 1 cam at a time u run the risk of bending more valves
as the cams arent being turned together at the same time.

If the pistons are all half way down the cylinders and not moving, you can move the camshafts all you want and not worry about hitting anything. You are already going to have SOME damage, just rotate it the right way to not do any more to get them all half way down.

[petejw]

If the pistons are all half way down the cylinders and not moving, you can move the camshafts all you want and not worry about hitting anything. You are already going to have SOME damage, just rotate it the right way to not do any more to get them all half way down.

hi cy,
its not the fact that the valves will hit the pistons, but if u
move the cams independantly of each other u run the risk of
the valves hitting each other, more than likely hes bent valves
but until he knows for sure, why risk it.

hi jason,
ur right it is a mute point, he will need to remove the head,
but u mentioned u could rotate the cams, i just stated if u did that
u run the risk of the valves hitting each other.

[BA80]

hi cy,
its not the fact that the valves will hit the pistons, but if u
move the cams independantly of each other u run the risk of
the valves hitting each other, more than likely hes bent valves
but until he knows for sure, why risk it.

hi jason,
ur right it is a mute point, he will need to remove the head,
but u mentioned u could rotate the cams, i just stated if u did that
u run the risk of the valves hitting each other.

Yup, natemoen found that out the hard way. And the head was already off the engine.

[natemoen]

Yup, natemoen found that out the hard way. And the head was already off the engine.

I even had the forethought to place the head up on blocks to prevent the valves from hitting the table...just didn't think about the other valves.

[TopCatGr58]

Yup, natemoen found that out the hard way. And the head was already off the engine.

Nate, et tu brute`? BTDT myself during my original rebuild in 2000. Had the head off, had done the valve lapping, thought it was a good time to check the valve clearances so put both cams in! Turned one, checked clearances, then turn the other, found excessive clearances..thought I had bent it against the table it was on! Replaced that valve, put the head on, torqued, timed, etc, then did a compression check just for S & G's, found 0 on 2nd cylinder! Had to tear it down. Found the opposing valve that had gotten slightly bent when it had hit the previous valve that got obviously bent! I THEN learned/realized that the valves WILL hit each other if they come out at the same time! Replaced that valve, and was good to go!

So....yes, turning the cams not in synch/time with each other can lead to MORE bent valves!

T.C.

[BA80]

I did find that if you set the opposite cam in the right position you can rotate the other 180º without hitting valves. At least on the early heads with smaller valves. I haven't tried it with a late one.

[skids]

I wonder if that would happen on the 78E valves, given the intake valves are smaller diam than the later models?

[BA80]

I did find that if you set the opposite cam in the right position you can rotate the other 180º without hitting valves. At least on the early heads with smaller valves. I haven't tried it with a late one.

Sorry....I meant 360º.

[BA80]

I wonder if that would happen on the 78E valves, given the intake valves are smaller diam than the later models?

78 & 79 are the same. 80 and up have the larger intakes. Nates engine is a 78.

[natemoen]

As Greg pointed out, nope doesn't work.