front seal + timing belt

[92sho16]

I did a search and i couldnt find the answer still. I am doing the front seal and i read you have to take the timing belt off. How do you know if the belt is in the right configuration when its put back on ?

 

[shobikes]

Yes- you must remove the timing belt. You're probably going to want to retime everything on assembly. What we did (See my post - "First 60k..." in this forum) was before removing the belt or anything, use the starter to repeatedly bump the engine over until the two marks on the belt were lined up with the two marks on the cam gears and close to pointing straight up. Since the cams turn once for every two engine revolutions, this should happen once every other full rev of the engine.

The new belt (I am assuming you are replacing belt) or even the old belt will have three marks on it - two at the cam gears, and one below, at the crank gear. Put the belt on so the writing can be read from the rear of the engine (upside down from the side you're standing when installing it), and when the engine is properly timed, the three marks will line up with the three marks on their respective gears, and the crank gear mark will also be lined up with the bump on the oil pump housing - at about 5 o'clock on the aluminum adjacent to the crank gear. For further reference, the keyway should be straight up, as well.

FWIW: The front cam seems to happily sit right where it needs to be. The rear cam will probably be hard to position if it moves - the orientation of the cam lobes makes it "pop" over-center in both directions. Wrap the belt around it and use it like a sling to carefully position it. Prepare to cuss at least once.

 

[autobahnsho]

And if the rear cam DOES "pop" (I like that sound for it! ) it becomes easier to turn it over the other way again.. I used a large piece of broken wrench to manhandle it, just be careful to not chip or crack the cam gear!!

 

[CALL AAA]

Just so I'm clear on this, if you rotate the cams, while the heads are bolted to the block, is there a chance that the valves can hit the pistons. Or even with Stage 1 cams, is it still NOT an interference engine? (is that the right word for it?)
If that made no sense, read on:

To get everything lined up, to put the heads back on, should I line up all the marks, before bolting the heads on? Or can I spin the cams, without the valves hitting any pistons that are all the way up?

Thanks,

 

[sdpatt]

The SHO engine is non-interference meaning that the pistons and valves do not overlap. You can spin the cams as much as you want separate from the crank. The only thing is that you have to align the index marks before installing the timing belt. Here is the topic showing the required alignment of teh cam and crank pulleys. You really need a service procedure to perform the belt removal/installation and the replacement of the front main seal. There have been manyposts on these topics. You can also check out the AutoZone service procedure link at the top of this section.

 

[CALL AAA]

Thanks, Scott.
I use a Helms manual, which has a pretty good description, but it doesn't mention when it's possible to turn the cams/crank, when installing. Does it become a problem, when you increase stroke?

 

[sdpatt]

Stroker crankshafts usually don't increase the height of the piston at TDC, but higher lift camshafts (i.e. Stage II) can cause interference if the timing is not maintained.

 

[CALL AAA]

Oh, yeah. I guess no one would make a cylinder come up higher than the block.
Duh!
Thanks, Scott.

 

[K-Dawg]

A strap wrench works very well for positioning the rear cams.