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Re: TR6 Timing sprockets

To: triumphs@autox.team.net
Subject: Re: TR6 Timing sprockets
From: "Robert M. Lang" <lang@ISIS.MIT.EDU>
Date: Thu, 30 Mar 2000 19:42:36 -0500
Hi,

Kieth Ehrlich was asking about timing chains and sprockets and stuff.

Bottom line: the new stuff doesn't have the markers like the originals did.
In fact, several that I have purchased and used didn't work like the
originals - you couldn't "rotate" them to get a 1/2 tooth of advance/retard.

You then need to make the marks on the gears _after_ they are installed.

If your sprockets don't have marks, someone in the past has changed them on
that motor. And they didn't do what they're supposed to do and mark it
after the timing is set.

Now, the initial message brought up whether this would effect your ignition
timing. The answer - well, while cam timing and ignition timing are
related, but - if your cam timing was way off, you car wouldn't run. Why?
Because the valves would be opening and closing at times that would cause
less compression (possibly) or not enough intake/exhaust breathing to
effectively scavenge the cylinders.

If you want a _theory_ as to why you need the large amount of ignition
timing that you site, I'll offer that maybe the lower crank pully has
rotated in the rubber a bit.

On the other hand, you indicate better power with the "n" degrees of timing
advance that you quoted (sorry, I don't have the original message), think
of it this way - that's what racers to to get the most power they can...
keep advancing 'till it pings and then back off a bit. It's called "power
timing".

If you swap in a new chain etc., you should put in a new tensioner.
However, make sure whatever you put in there is "good" to start with. The
ISOA newsletter has had some very detailed articles by Joe Pawlak about the
quality of components being sold for our cars, and being cautious is def.
the order of the day. If in doubt about any parts, get a second opinion!!!
And find a good machinist. And I hope that VTR might run some of Joe's
articles in TVT sometime... hint, hint. Note: great job on the articles, Joe.

Me - I gave up on the "big gear" parts that I had purchased before and paid
the extra $$$ to get a dial-in adjustable vernier cam gear. I can now put
the cam timing wherever I want it.

Hint - if you want to screw with the power a bit, you can get gains by
advancing the stock cam, but you need access to a dyno to know exactly what
you are doing... in other words, this is not a process for amateurs.

Good luck!
rml
p.s. I don't live that far away from you Kieth, give me a call sometime...
_after_ I get the race car actually racing.

=====================================================================
Bob Lang      | TR 6 Guy           | Editor: New England Triumphs
Phone:        | 617-253-7438 (days)| 781-438-2568 (eves)
Occupation:   | ComputerZ          | TR fixer-Upper
=====================================================================

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