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Discussion Starter #1
I removed the head on my 78 Z, and now during reinstall I can't get the cam sprocket back on (chain is too tight).

Are there any tricks to getting it back on?

I didn't put the wedge in when I removed the sprocket as described in the Haynes manual, and my guess is the tensioner has expanded and took up the slack I need to get the chain lined up correctly.

One guy told me I might be able to force the tensioner back by loosening the camshaft tower bolts, tilting the cam from the rear, sliding the sprocket back on with the cam tilted, and then pushing down on the rear of the camshaft and using the tower bolts to tighten the camshaft back down.

This sounds like it's too risky. I don't want to damage any of the bearings or strip any of the tower bolt holes, or stretch/snap my timing chain.

Is the tensioner hydraulically operated, or pure mechanical? Seems like if it's hydraulic, then this trick would probably be OK, but if it's mechanical I might be in for trouble.

Any help out there? Has anyone successfully compressed the tensioner without having to remove all the timing cover stuff?

-Rob
 

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Discussion Starter #2
Re: Help: What's the trick: Cam Sprocket/Timing Ch

> I removed the head on my 78 Z, and now
> during reinstall I can't get the cam
> sprocket back on (chain is too tight).

> Are there any tricks to getting it back on?

> I didn't put the wedge in when I
> removed the sprocket as described in the
> Haynes manual, and my guess is the tensioner
> has expanded and took up the slack I need to
> get the chain lined up correctly.

> One guy told me I might be able to force the
> tensioner back by loosening the camshaft
> tower bolts, tilting the cam from the rear,
> sliding the sprocket back on with the cam
> tilted, and then pushing down on the rear of
> the camshaft and using the tower bolts to
> tighten the camshaft back down.

> This sounds like it's too risky. I don't
> want to damage any of the bearings or strip
> any of the tower bolt holes, or stretch/snap
> my timing chain.

> Is the tensioner hydraulically operated, or
> pure mechanical? Seems like if it's
> hydraulic, then this trick would probably be
> OK, but if it's mechanical I might be in for
> trouble.

> Any help out there? Has anyone successfully
> compressed the tensioner without having to
> remove all the timing cover stuff?

> -Rob
Well I've seen messages like this before...
Take the time to whittle a wedge to your liking,Haynes dimensions will get you close then fine tune it a little bit,
needs a slight curve on pass. side to keep chain tight to tensioner.
Then work it in while pulling up on the chain with your hand.
As far as I know the tensioners are more like a guide for the chain. Don't move.
Let's hope the chain didn't move/fall off of the crank sprocket ,if so someone else may be able to tell you the proceedure to get it back in time clearer than me.
For anyone else that's going to remove their head,take the time to make a wedge(I used oak)
now and save yourself a heap of time and agony later.....

Good luck!

Jeff
 

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Re: Help: What's the trick: Cam Sprocket/Timing Ch

> I removed the head on my 78 Z, and now
> during reinstall I can't get the cam
> sprocket back on (chain is too tight).

> Are there any tricks to getting it back on?

> I didn't put the wedge in when I
> removed the sprocket as described in the
> Haynes manual, and my guess is the tensioner
> has expanded and took up the slack I need to
> get the chain lined up correctly.

> One guy told me I might be able to force the
> tensioner back by loosening the camshaft
> tower bolts, tilting the cam from the rear,
> sliding the sprocket back on with the cam
> tilted, and then pushing down on the rear of
> the camshaft and using the tower bolts to
> tighten the camshaft back down.

> This sounds like it's too risky. I don't
> want to damage any of the bearings or strip
> any of the tower bolt holes, or stretch/snap
> my timing chain.

> Is the tensioner hydraulically operated, or
> pure mechanical? Seems like if it's
> hydraulic, then this trick would probably be
> OK, but if it's mechanical I might be in for
> trouble.

> Any help out there? Has anyone successfully
> compressed the tensioner without having to
> remove all the timing cover stuff?

> -Rob
I got mine back in once with a really long, skinny, flathead screwdriver. I can't remember if I got to the tensioner through the top of the timing cover or through the front main seal. If you take out the front main seal in the timing cover, you can reach the tensioner with a skinny screwdriver and sometimes you can push the tensioner back in, USE THE WEDGE THIS TIME!!!!!!!!
 

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DONT FORCE WITH CAM TOWER TRICK IT WILL RUIN HEAD

I did the same thing 8 years ago removed chain sprocket with out wedge.Sorry to tell you this but you need to take the front timing cover off.Its a real PAIN but it is the only way to ensure your cam and crank timingmarks line up!!! If you try that CRAP with the towers you will be sorry.Do it the right way and you wont have to worry about destoying your engine!!!! Later,Norm
 

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Discussion Starter #5
Found The Trick

<HTML>


Thanks for the ideas, folks. It IS possible to depress the tensioner and get the sprocket back on without having to disassemble everything. I just did it, and it worked.

I used an engine hoist, a rugged tie-down strap with rubber-coated hooks, a prybar, a screwdriver, a plastic tipped hammer, and a 1/2 breaker bar with a socket. I put the hoist over the cam sprocket, hooked the tie-down strap to it, and hooked the other end of it into one of the holes in the sprocket. Then I pumped the hoist slightly to put a good pull on the sprocket for tension.

I put the screwdriver handle into the chain housing (used it as a cushion for the prybar) and put the long prybar down into the chain housing until it touched gear at the bottom, then I backed it up a bit to where it seemed like its worn, rounded end was resting against the tensioner area. Then I used the breaker bar/socket to turn the crankshaft while I pulled pressure on the prybar. I pulled on the taught strap to center the cam sprocket.

And it worked. The tensioner released a bit, giving me more slack on the chain. The heavy pull of the engine hoist pulled the sprocket+chain up, and I tapped it onto the camshaft, being careful to have the crank pully at the TDC notch when I tapped the cam sprocket on.

So if anyone tells you that you absolutely have to disassemble the cover (and its dozens of but first... disassemblies...) to get the slack back in your chain, remember that you can pry the slack back in if you're really in a pinch. I could've destroyed my chain, sprocket, housing, etc. but I didn't, so I guess I was lucky.

Pulling straight up on the sprocket/chain had no effect. It was only when I started moving the crank pully that the tensioner backed off.

Just thought I'd let you know.

I wanted to keep the crank near TDC, so I turned it back and forth while pulling on the prybar.

</HTML>
 

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Discussion Starter #6
Re: Found The Trick

Now all you have to worry about is if the chain skipped a tooth or 2 one way or the other off of the crankshaft gear, your cam will probably be off timing, Hope it's not but you should do things right or your going to have headachs with it, sorry you didn't use the block but it's ok to learn by mistakes. I learned that way a few times also. You should have seen my first rebuilt engine.. ouch... good luck..
 

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Discussion Starter #7
Dang! Timing's off, flunked smog...

> Now all you have to worry about is if the
> chain skipped a tooth or 2 one way or the
> other off of the crankshaft gear, your cam
> will probably be off timing,

It runs, but I got a pre-smog test and it exceeds one of the emissions by twice the allowed limit. The printout said the probable cause is either the timing's off or there's a vacuum leak. A vacuum leak is probable because I guessed at some of the vacuum line routing, but a timing problem is more likely because of the mess I got myself into, and because of how I got out of it.

My guess is I skipped a tooth on the sprocket, and I'll have to take it off again. But THIS TIME I'll use the wedge!....

Any advice on how to determine which way I'm off? How will I know if I have to move the cam sprocket one notch to the right, or one notch to the left?

-Rob
 
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