Hi Mark and Dick,
Here in NZ, we went to unleaded four or five years ago and phased out the
normal leaded petrol. The reasons for the change were mainly due to
politcal lobbying by green peace and the likes. In effect we have replaced
the evil lead with other wonderful chemicals like tolulene and benzene but
that is another story for another day (don't get me started on this one...)
There has been much confusion with the saloon Tiumphs as it appears some
models did have hardened valve seats (these were stellite faced). The
models with this had the smaller 30.3mm valves rather than the larger
valves. I am not sure if this applies in the States. In 1975, the saloon
cars were facelifted, and it was from this point on that the saloons
supposedly had hardened valve seats. As I said, I'm not sure if this
applies to the US Spec cars. I think I have a list of engine numbers so
I'll try and dig that out tonight when I get home.
With talking to various club members, the problem of valve seat recession
seemed only to occur on the higher compression ratios (thus affecting the
2.5 PI's TR5's, TR6's, Dolomites and Stags). One friend who uses his car
for commuting has put in nearly 200,000 miles on unleaded and suffered no
problems with VSR (he lives a long way out of town!). However, his is a 2
litre 6 (same as the GT6) with a low compression ratio (8:1).
With the larger valves, I have been advised not to fit hardened valve seats
as there have been reports of the seats dropping out if the motor is
overheated. Someone with more expertise than I may have some info on this...
I agree entirely with Dick, basically suck and see. Just keep an eye on the
tappet clearances when you do the regular maintainance. Any VSR will be
clearly noticable by a closing up of the tappets.
Hope this helps (and isn't too longwinded!)
Cheers
Bernard Robbins
'71 2500 PI (still no reverse gear so can't get it out of the drive!)
'73 TR6 (passed its MOT with flying colours woohoo!)
At 23:37 17/07/00 -0700, Sally or Dick Taylor wrote:
>Mark---Here's my version of the "quick and dirty."... Unfortunately,
>some of our suppliers like to try to scare owners of the TR6 into buying
>a few of their products, claiming the _______ will self destruct if this
>or that part isn't changed. So it is with the hardened valve seat
>inserts that can be installed in the heads of all TR6's. The valve seats
>from the factory are part of the cast iron head. (They must be machined
>out if the hardened ones are to be installed.) Since non-leaded gas is
>all that has been available for a good many years now at major service
>stations, it must now be obvious that our engines will run on this
>without undue harm. As a precaution, or check against such wear in the
>valve seats, a simple check can be performed. If your valve clearance
>(lash) between the rocker pads and the valve stems is not becoming
>smaller, there is no problem to deal with. Most stock clearances are set
>around .010. This clearance usually grows larger thru wear in the valve
>train, over many miles. Just check your valve clearances as routine
>maintenance, and adjust accordingly. Heavier valve springs such as
>those needed for racing cams may need to be checked more often.
>
>Dick T.
>
>
>
Regards
Bernard Robbins
NEC New Zealand Ltd
Network Solutions
P.O. Box 1936
Wellington
Ph (04) 381 6274
fax (04) 381 6284
email brobbins@wlg.nec.co.nz
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