[6pack] TR6 Combustion Chamber

[Ruffner, James A *HS]

Once again the "unleaded gas" boogie man.  Many years ago when I purchased a
'60 TR-3A, which I still possess, (it was used) I asked Bob Tullius, who
worked at the Triumph dealer at the time, and who was sponsored by Triumph,
what was the best gas.  He emphatically stated "use Amoco unleaded. It costs a
bit more, but is the very best for the engine."  I have had a valve or two
burn over the years (poor valve clearance set by the shop!) but never a
problem with recessed valves.  I still have a couple of original heads in the
basement that never needed any work on the valve seats.  I'm about to pitch
them.
________________________________________
From: 6pack-bounces at autox.team.net [6pack-bounces at autox.team.net] On Behalf Of
brian at asmoothmove.biz [brian at asmoothmove.biz]
Sent: Friday, March 09, 2012 12:27 PM
To: 'Cregg Cowan'
Cc: '6pack'
Subject: Re: [6pack] TR6 Combustion Chamber

Cregg: I think 9.25 is smart. You should have less trouble with fuel and
timing than I did.

Attached are two pictures. One shows the chamber after the work was done and
the marked-up version highlights the edges that were rounded out. The
rounding/smoothing was very modest - not a lot of material was removed, just
enough to take off the sharp edges.

Please warn your machine shop to be very careful not to encroach onto the
gasket sealing area when they are using the die grinder, particularly
between the cylinders. Cylinders 1 and 2, 5 and 6 are VERY close together
and you don't want to mess up that narrow sealing surface between them. A
good shop will take steps to ensure that the sealing surfaces are protected
by an errant die grinder hit.

May I say as long as your head is being worked on, I strongly recommend
having hardened exhaust seats installed. This eliminates the worry over
unleaded fuel and your exhaust valves. I even went with installing brass (or
bronze?) guides on the exhaust side as another upgrade.

Brian J. Alwin
1972 TR6 CC79085


-----Original Message-----
From: Cregg Cowan [mailto:cregg.cowan at sri.com]
Sent: Friday, March 09, 2012 10:54 AM
To: brian at asmoothmove.biz
Subject: TR6 Combustion Chamber

Hi Brian,

It so happens that I have my '73 head off right now for valve work and
decided to have it shaved (to a more modest 9.25 CR).
Can you point to a description of which sharp edges need to be removed?
I have the Comp Prep guide but haven't studied as carefully as I should,
I guess.

Thanks!
Cregg
Mountain View, Calif.

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marked up.jpg]

[demime 1.01d removed an attachment of type image/jpeg which had a name of
Photo549.jpg]

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