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Re: chain tensioner

To: "Jack W. Drews" <vinttr4@geneseo.net>
Subject: Re: chain tensioner
From: "Michael D. Porter" <mporter@zianet.com>
Date: Sat, 29 Mar 2003 21:26:14 -0700
"Jack W. Drews" wrote:
> 
> I'd like to have a TR3 - 4 timing chain tensioner that is longer-lived than
> the crummy little sheet metal flapper.
> 
> Has anybody seen something in another manufacturer's engine that could be
> adapted?

Most later engines use an hydraulic tensioner. The tensioner block is usually 
connected to a shaft
which acts as both a guide and a piston, and fits into a small aluminum block 
connected to an oil
gallery in the engine.

The problem with fitting one to the TR3-4 block is one of space. One of the 
most compact tensioners
of this type I've seen is from a Datsun 510 engine, and it doesn't have enough 
room to be installed
without modification to the timing cover. 

But, part of the good wear characteristics of the later tensioners is that they 
use either dense
nylon or ultra-high molecular weight polyethylene (UHMWPE) on the face 
contacting the chain. I
wondered about making a block out of that stuff to fit the curvature of the 
chain with a spring
behind it, pushing on the timing cover, but haven't gotten too far with that 
idea yet. 

But, from working with UHMWPE in the past, I know it to have good natural 
lubricity and excellent
wear characteristics. The principal problem with it is that it has to have 
sufficient depth of
section to be bolted or riveted to whatever substrate is being used--it doesn't 
glue worth a damn.
Even the specialty cyanoacrylates made for gluing it have very low mechanical 
strength. 

Cheers. 

-- 
Michael D. Porter
Roswell, NM (yes, _that_ Roswell)
[mailto:mporter@zianet.com]

Don't let people drive you crazy when you know it's within walking distance.

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