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Inner and Outer Collar on Exhaust Valves

To: "6 Pack List (E-mail)" <6pack@autox.team.net>,
Subject: Inner and Outer Collar on Exhaust Valves
From: Hugh Fader <hfader@usa.net>
Date: Sat, 27 Apr 2002 16:45:30 -0400
Well, I made some progress on my TR6 engine today. I installed my timing
gears and degreed the cam. I ended up putting the shims I bought for the
crank gear behind the cam gear. They just fit around the two cam gear bolt
holes, so should not slip out.

While degreeing the cam, I wanted to make absolutely sure I was using
cylinder 1's intake valve not it's exhaust valve. I determined it was the
second valve from the front by looking at the valve sizes in the cylinder
head.

I also observed that the intake valves have the double collar installed.
Bentley is unclear about which is which, so I took a look in the Roadster
Factory catalog. (Those drawings are invaluable.) Turns out the exhaust
valves are supposed to have the double collar.

I don't know whether the machine shop made an mistake or if they duplicated
the previous owner's assembly mistake. Anyway, glad I noticed! What kills me
is that I just had all the valves out last week to clean up the head. I know
I didn't mis-assemble, because each valve and it's associated parts went
into its own baggie.

So now, my question is: What is the function of the double collar? The
exhaust springs will have more pre-load and more load when fully open. Is
this to keep them from binding or something?

- Hugh Fader

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