Jose Posted December 6, 2014 Report Share Posted December 6, 2014 Hi all, After one and a half years I still do not have my TR7 on the road. I have been fixing small things until I found out it has a broken exhaust valve. I have the head off now and I am wondering if there are other things I should take care of. I will change al valves as a matter of course, but I am wondering, are they prone to failure? I was thinkng in changing the timing chain and sprockets. I looked at RB and they offer a standard and a more expensive german chain, so I googled a bit to see what the difference is and read some comments saying they are no better and that the sprockets on sale now will break quickly, would it be better to keep the current ones which seem to be OK? Thanks! Quote Link to post Share on other sites
chris turner Posted December 6, 2014 Report Share Posted December 6, 2014 Why has the valve broke. I had a bucket break on a newly rebuilt engine, from now on I will only use original buckets. Obviously it broke the top of the valve and wrecked the NOS cylinder head. Quote Link to post Share on other sites
TriumphV8 Posted December 6, 2014 Report Share Posted December 6, 2014 Do not know about the quality of TR7 chain but there is a big difference between the replacement cheap chain and the one from German IWIS at TR6. As there is no tensioner on the TR6 you can see a huge stretch after short use. Although there might be a tensioner the timing will get worse. When valves fail beside poor quality and no reason to be found there are some reasons, that should be checked: First there is the poor valve clearance that prevents the valve getting rid of the heat when to tight. The valve can not rest on the seat what would allow to pass the heat from valve to head or when getting more worse will allow the hot gas to pass the slit between seat and valve and fry the valve. One more reason that should be checked is if the seat is in line with the valve guide and allows the valve to seat nice and full on the seat all around. Quote Link to post Share on other sites
john.r.davies Posted December 6, 2014 Report Share Posted December 6, 2014 (edited) Andreas, There is, or should be a tensioner on the timing chain of a TR6! See: http://www.canleyclassics.com/triumph-tr6-late-timing-cover-details Part No. 145866 John Edited December 6, 2014 by john.r.davies Quote Link to post Share on other sites
TriumphV8 Posted December 6, 2014 Report Share Posted December 6, 2014 (edited) Hi John! That funny sheet of metal is not worth being called a tensioner. It smoothes a little bit the tendency of the chain to swing on the powerless side but not more. I tried that with a fixed timing advance from my Megasquirt picking the trigger from the distributor that is welded for fixed timing.. You can see the timing jump at some lower revs and timing going backwards at very high revs from the chain riding higher on the teeth. I believe responsible for that is the play in the chain and from that I would try to get a chain very tight that keeps being tight fit over the mileage. So one has not to rely on that the tensioner does its work. But another argument for the IWIS is that the sides of the chain feel noticeable smoother and from that will not wear the "tensioner" that much. Edited December 7, 2014 by TriumphV8 Quote Link to post Share on other sites
Jose Posted December 6, 2014 Author Report Share Posted December 6, 2014 Thanks for the responses, I have no idea how the valve broke. When I bought the car it didn't even start after 10 years storage, but it was already broken. Good point about valve seats, they seem to be Ok, but will be lapped together with the valves so if this was the cause hope it does not happen again. Quote Link to post Share on other sites
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