hardened valve seats

[Guest lister]

can anyone tell me if the tr7 sprint engine has hardened valve seats and can therefore run on unleaded without modification.

 

As engine is going for a face clean and i would get it done at the same time .,

 

 

Thanks

Al

[mikehardwick]

Al

 

My car covered over 25000 miles in 4 years on unleaded with no adverse effects I am aware of. Certainly, the head - being alloy - had hardened seats fitted as standard by the factory.

I have heard it said that the seat inserts used are not up to the task of running unleaded, and some specialist firms offer an 'unleaded' conversion, but I have not yet seen any evidence that this is neccessary.

 

Mike

 

P.S. The reason for the past tense in the first sentence above is not engine failure - I went for a V8 conversion.

[Guest lister]

thanks Mike.

This seems to be the cencus of opinium on both this and the club triumph forum. So i'll go ahead and leave it as is and only change if there is a problem .

 

Thanks for the information again

 

AL

[Guest jeffremj]

The information I have come across over the years say the following:

 

1) Brico manufactured all(?) the valve seats for ali headed UK engines (Rover V8, Dolomite/TR7 engines)

2) I believe they were all to the same spec.

3) Brico said that the sintered seats are OK for normal use with unleaded

4) US TR7 valve seats are the same as UK items and the US has used unleaded since around 1980 (IIRC)

[malcolm]

Handy information that. So what are those 'unleaded' spec engines suppliers are trying to flog us at extra cost then??

 

Malcolm.

[anthonyt]

Some would call that marketing Malcolm, (though i personally feel that it is dishonest) caveat emptor i suppose.

[raydrink]

This subject has occurred many times in Stag fora (is that the plural of forum?) and the comparison has often been made with TR7 engines. The feeling has always been that the both cars' heads have always had valve seats that permit the use of unleaded fuel. The question has been whether the exhaust valves are up to the job.

 

In discussing the valves used in Stags it has been asserted that the Stag engine often used the same valves as the TR7, though the precise cut-in date or indeed the question of whether TR7 valves were used when Stag valves ran out, has never been precisely ascertained. The upshot of it has been that if the Stag did use TR7 valves throughout its life, then they could all run unleaded. Ergo TR7s can and have always been able to run unleaded as there was no difference in the UK and USA engine build specs (in that area anyway), and the USA was running unleaded when the TR7 was launched.

 

Unleaded exhaust valve has part number 155524.

 

Yes there are outfits out there who prey on the uncertainty of which valves are in 'your particular Stag guv' in order to get unsuspecting punters to part with hard-earned cash to have their heads converted to unleaded, but unless my memory is playing tricks there should be no such uncertainty about TR7s.

 

regards

Ray

[Guest jeffremj]

Handy information that. So what are those 'unleaded' spec engines suppliers are trying to flog us at extra cost then??

 

Note that I said 'normal' use :-)

 

The Brico sintered items (Stags would have used exactly the same material as Rover V8s and TR7s) are not as hard as 'fully' unleaded valve seats and so if I was supplying recon heads, I would use the 'best' seats available at the time.