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Unleaded conversion

Alastair Smith

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I am a newbie on the forum so forgive my question which I am sure must have been asked before. 

I am four years into a nut and bolt restoration of a Mk1 GT6, will be done next summer, and I am wondering about the conversion to unleaded. I believe, from what i have read, that this may not really be necessary but if I do go ahead with it could someone recommend a shop in the Yorkshire area to do the work please?  And an indication of what cost I should expect? 

Many thanks. 


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If you have the head off and doing engine work, I would do the conversion. Or at least have hardened seats fitted to the exhausts. You may want new valves too depending on how yours are. And while you are at it, get 3 angle seats cut (last lot I had done 8 years ago were £3 each in Sussex, I pay more than most except Londeners) And I think I paid £20 a seat. 

It may be worth getting a light skim while you are there, after all if the engine is apart..... (maybe new crank bearings and thrusts, even a hone and set of rings?)

I know the costs add up, but much easier now.


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Yes if left untouched theres years of lead memory in the casting and valve seats,  no need for any addatives .

But if the engines  being dreamt of a refurb then Clive right nows the time 

If the plan is to rebuild the car but leave the engine to see how it runs , well leave well alone , maybe decide later

This is the old compromise or utopia issue , if you expect to do many miles throw some budget at it but if its only sunday tootling 

Wait and see how she performs



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My Mk1 Vitesse had an unleaded conversion under a previous owner. My Mk3 GT6 gets driven a lot more and a fair bit harder and is still on the old lead memory. Neither car has shown any valve problems. I agree with Pete that it's a matter of what else you're doing. If you're going to have any head work done, get the hardened valves & seats at the same time. If you wouldn't otherwise be meddling then leave it as it is.

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There are two factors to consider. The first is the lack of lead in the fuel. I agree with all the comments, only get the head converted when other work is required. I have seen valve recession but only after the Triumph had been regularly thrashed up and down a motorway towing a boat. In others words after extremely hard driving. Not too sure how the owner hadn't already blow up the engine!

The second is the octane rating. The standard, premium, unleaded fuel is 95 octane which is a bit low for the GT6 engine. Either use an octane booster with premium unleaded or use super unleaded. Look for 97 or a higher octane rating.


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