jbenajes Posted March 11, 2009 Report Share Posted March 11, 2009 Hello, The supposed correct 3/8" stem diameter exhaust valves and corresponding guides do not fit my cylinder head, and the thinner 5/16" stem valves seem to be required. Egine number is TS61378E, but I suspect now that the cylinder head can be of a later engine version (perhaps TR4A). The casting has the following numbers on top, close to the exhaust valve of cyl #4: 302137 V2528 How can I tell? I cannot recognise the casting numbers on the head, nor the shape of the combustion chamber, that you can see in the attached photo. Any hint? Thanks. Jesús Quote Link to post Share on other sites
TorontoTim Posted March 11, 2009 Report Share Posted March 11, 2009 Hello, The supposed correct 3/8" stem diameter exhaust valves and corresponding guides do not fit my cylinder head, and the thinner 5/16" stem valves seem to be required. Egine number is TS61378E, but I suspect now that the cylinder head can be of a later engine version (perhaps TR4A). The casting has the following numbers on top, close to the exhaust valve of cyl #4: 302137 V2528 How can I tell? I cannot recognise the casting numbers on the head, nor the shape of the combustion chamber, that you can see in the attached photo. Any hint? Thanks. Jesús Although yours may have specific modifications, see this site for the low-down on all the TR heads. This should give you a good starting point... http://www.tjwakeman.net/TR/FAQ_heads.htm Quote Link to post Share on other sites
Don Elliott Posted March 11, 2009 Report Share Posted March 11, 2009 If the engine number you have quoted is correct for your TR3A, I guess that your TS number is close to TS 61100. That would mean that your TR is a 1960 or 1961. What was the octane rating for petrol in Spain in 1960 ? Pehaps you have a special head designed for low compression if the octane rating was low at that time. The large chamfer we see in your photo would lower the compression ratio by increasing the volume of the combustion chamber in the head. Quote Link to post Share on other sites
jbenajes Posted March 11, 2009 Author Report Share Posted March 11, 2009 Thanks for your inputs. Tim, the link is very useful, I will try to compare the details with my cylinder head and to discern from here. Don, my TR3A commission number is TS61256L. In 2007, I imported the car from the USA, where it was delivered at the end of 1959, so it must have USA specifications. The car has all matching numbers, according to the BMIHT. The engine has been reconditioned along its life, and it was fitted with 86 mm pistons. From your comments I guess that the chamfer in the combustion chamber is not original in TR3 cylinder heads. If this is the case, I wonder if this is exactly the evolved combustion chamber in the TR4A, or only something in between, perhaps to increase chamber volume and hence adapt compression ratio to the larger displacement. Jesus Quote Link to post Share on other sites
Rhodri Posted March 11, 2009 Report Share Posted March 11, 2009 Jesus- I have those two casting numbers on my TR4A head. I believe that the 5/16 valve stem is correct for a TR4A. Rod Quote Link to post Share on other sites
jbenajes Posted March 11, 2009 Author Report Share Posted March 11, 2009 I have read the information in the useful link supplied by Tim above, and comparing with the attached photo of my engine, it seems that the cylinder head corresponds to figure 4 in that web page, and hence comes actually from a TR3B or a TR4A, as suspected. Any comments? Jesus Quote Link to post Share on other sites
jbenajes Posted March 11, 2009 Author Report Share Posted March 11, 2009 Jesus- I have those two casting numbers on my TR4A head. I believe that the 5/16 valve stem is correct for a TR4A. Rod Thanks for the information, Rod. Our posts were uploaded at the same time, and I could not read yours before sending mine. Jesus Quote Link to post Share on other sites
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