Cylinder Head Removal - Part Two

[bobc]

Ok, I think I'm semi-screwed....

I got the head off and besides the three busted bolts on the exhaust manifold to collector pipe it went pretty well...until, that is, I noticed that the link on the timing chain with the white mark wasn't were is was supposed to be.

At one point I had the cam sprocket in the right position (line and groove matched) and the link with the white mark was at the top of the sprocket. I messed with the engine after that, but thought I had it back in the right position.

When I looked after lifting the head off, the white mark appeared to be gone. At first, I thought it might have been wiped off, but then saw if much further down the chain.

I thought I was at TDC when I pulled the head, because number one piston was up, both valves were closed and the rotor in the distributor cap was pointing at number 1.

I've attached some pictures for help. Number 1 and number 6 pistons are fully up. You can see the white link in the picture next to the orange tool on the left.

I'm thinking that when I put it back together I'll put the chain on the sprocket in the best fit possible. I may be off a link or two. Then, without the head bolts, I'll turn the crank until I eventually get to where the white link is at the top, #1 piston is at the top, and the groove and line on the sprocket match up.

Short of pulling off the timing chain cover (really don't want to do that) does anybody have a better plan.

Perhaps someone can tell me what position the cam and crank should be in at TDC?

Thanks.

Bob

[ktm]

At one point I had the cam sprocket in the right position (line and groove matched) and the link with the white mark was at the top of the sprocket. I messed with the engine after that, but thought I had it back in the right position.

You probably did not re-align the mark after messing with the engine. The white mark is "behind" the chain wedge. There is no way for the chain to slide behind the tool with the tool in-place. You'll know if the chain slipped and the tensioner popped out because you will not be able to install the chain on the cam sprocket.

[Curtis240Z]

You might have turned the engine when you were loosening the cam sprocket. All bets are off now. Everything is a gamble without pulling off the timing cover. Sorry.

[bobc]

Thanks for the help so far. Couple of items. I'm sure the chain has not slipped and everything was all together (sprocket bolted to the camshaft) right up until the time I took it off, so the sprocket didn't move either. I'm also sure that the engine didn't move because the timing mark was pointing directly to the TDC groove on the pullley at the start and the finish of removing the sprocket.

It was weird because everything was exactly as I thought (key word thought!) it was when I did the original set up to see how it should look. The only thing that wasn't right was the mark on the chain. That's how I missed it, the pulley was aligned with the timing marker, the rotor was on #1 and the white marks I made on the sprocket were at the top of the sprocket and the sprocket groove lined up the mark on the cover. Just didn't notice that the chain link wasn't in the right spot. Nothing could have moved prior to me pulling the sprocket off.

I guess if I can't duplicate the setting, I'll have to pull the timing gear cover.

Thanks again.

Edited November 24, 2008 by bobc

[ozconnection]

This has happened to me in the past. Couldn't understand it. But there is some logic to it if you stop for a minute to think about it. The bright links on the chain are not exactly the same number of links from each other.

An example: Say there are 50 links total in the chain, and the bright links are separated by 17 links. Turn the thing over and it will take a while before all the 'bits' fall back to their respective positions. It would happen much more often if there were exactly 25 links of separation....do you follow?

Get a bicycle and experiment with the chain and mark two links with paint and make sure they are separated like the example above. Give it a go and you'll soon see what is happening in your engine.

Bottom line, doesn't line up with the bright links...who cares? So long as all of the other setup criteria is met, TDC, rotor pointing the right way, timing sprocket notches etc, you'll get it to run again properly. :classic: (Or you could have turned your motor when the head was still on with only the rocker cover off until the links were where they were 'supposed' to be).

[Carl Beck]

Hi Bob:

Sorry to hear your having too much fun with this.:stupid:

If you attempt to set the engine up using the approach ozconnection outlined - I'd suggest that you remove the rocker arms before you crank the engine over, until the bright links on the chain align with all the other criteria. Just a little insurance that you do no harm, and it is easy to be link off, so you'll want to verify before you close everything up.

But let's back up a bit - How many miles are on that engine?

If the engine hasn't been rebuilt in the last 5 years or more - You may have an unexpected, perhaps unwelcome, opportunity to replace an aging front main seal, timing cover seal, replace the timing chain tensioner with one that will not pop out the next time, and perhaps replace well worn chain guides. How old is that water pump anyway? Removing the front cover does offer the possibility of twisting off more rusted bolts that run through the water pump.... on the other hand better to do it now, than later.

I would guess that you removed, or had removed all the studs on the head while you were at it, and replaced them with new ones. 39 year old studs thermo cycled with engine temps, do suffer from metal fatigue, and their protective Cad. plating is usually gone as well. No sense twisting them off if you have to remove the manifolds at some point in the future. (pay attention to the lengths of the studs protruding from the head - as I recall there are a couple different lengths at different points)

FWIW,

Carl B.