Skip Montanaro writes:
>I adjusted the valves on my TR-250 the other day. They all seemed tight, at
>least compared to the .254mm gauge I was using. (After years of working on
>metric cars I have very few English measured tools...) Is that typical of
>the 6-cylinder Triumph engine (valves tightening over time)? That was a
>problem with the VW and 356 engines I used to work on (same adjuster
>mechanism), but I always thought that was peculiar to those cars.
This is a classis sympton of valve head wear or valve seat recession,
sometimes happens on TR 6-cylinder engines if:
a) not enough lead in the gas, and/or:
b) engine running at too high a temperature, or
c) Wrong valves
a) is difficult to do much about, all the petrol (gas) in the world has
been starved of its added tetra-ethyl lead for some years now, since some
scientist decided it damages the brains of our children. Octane boosting
additives sometimes claim to replace the lead, but most of these work by
using tin, and UK trials have proved that this doesn't work.
b) is easier - check all the usual things, backflush the radiator, flush
out the block, clear last falls leaves out of the radiator duct, etc. etc.
If all else fails, fit a more efficiant radiator, and electric fan, or
something.
c) I've had problems with spurious valves for 6-cyl TR engines. Some are
made of very nasty material and recess quite badly. Genuine valves are
still to be had, and those made by TRW seem to be OK. A final fix may be to
get a cylinder head from a late model Triumph 2500S (OK, I know there
weren't many in the US) which had Stellite valve seats and Stellite faced
exhaust valves.
I've run a 2500PI on unleaded fuel for about 30,000 miles now, I've had no
problems with the valve gaps closing, but I *did* until I'd attended to the
above.
Richard Smith
R.G.Smith Automobile Engineering - Triumph & Alvis specialist
- British parts for British cars
- Tel: (+44) 729 823051
- Fax: (+44) 729 824092
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