The head should be 4.528-4.530" thick if it is more than .030" less than that,
definitely buy shims. They come in varying thicknesses, and the idea is to get
the total back to the original spec.
If you don't have a mike that big, or if you've already reassembled your engine
with new chains and tensioners, you can do a "pragmatic check" this way: Rotate
the engine backwards until the chain is taut on the tensioner side. Then push in
on the chain just below the cam gear. If you can push it in enough so that the
chain touches the upper bracket, you need to either shim the head (best
solution) or shim the tensioner (next best solution). Of course, shimming the
towers may require that you pull the head off again and take it to a shop to get
the cam towers lined up again. Sometimes the luck is good, sometimes it isn't.
Gordon Glasgow
Renton, WA
> -----Original Message-----
> From: owner-datsun-roadsters@autox.team.net
> [mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Boutros
> Boutros-Ghali
> Sent: Monday, October 07, 2002 8:35 AM
> To: datsun-roadsters@autox.team.net
> Subject: How to measure if timing chain is in "spec"?
>
>
> I successfully removed the crank pulley bolt and pulley. Thanks to all who
> responded, I used the car-in-gear-handbrake method with a sizeable breaker
> bar. The pulley came off with a gear puller I adapted to pull on the two
> bolts I threaded into the inner pulley.
>
> Once I get the new chain installed, how do I tell if it is tight enough? If
> I have to shim the cam towers, how do I know how big of a shim to buy?
>
> I measured the head the last time I had it off and its thickness was within
> tolerance according to the reference manual. The block deck could have been
> milled too much, but I think the engine has only been rebuilt once.
>
> Thanks,
>
> Ken Pearce
> B'ham WA 68-2000
>
>
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