TR6 TR6--late/early model head question.

[ALLAN]

Which head has the intake ports closer together- late or early model?, I always thought it was the late head, Im in a debate with BPNW regarding which gasket fits what head.

 

[Guest]

early i think

 

[Telly]

Definitely not the late head. Always heard '72 through '76 was the same as the British spec (wider spacing) and '69 through '71 was made only for the American models. I suppose the break point could be based on commission number between '71 and '72.

 

[ALLAN]

The original head that came off my 71 has the wide spacing and the motor that Im using now came out of a 74 and its head has the narrow spacing. Also I have a spare circle B head (dont know what years they were) and it has narrow spacing. The intake gasket that came out of my late model gasket kit has narrow spacing, now Im really confused!! Now I wonder if I have the right head gasket on my late model block with the recessed groove, I was assured by BPNW at the time that it was a late model gasket kit they sold me. The gasket looked like it did have a ridge to fit down in the groove--not much of one though.

 

[MDCanaday]

The early style head was used till 71 it is similar to the gt6 head.One quick way to tell is the boss for the EGR valve (over #5 exhaust), in 71 the new head had an undrilled boss that sometime in 72 got drilled and fitted with this smog device.Dont forget to have at least 100 thou taken off any tr6 head that has not already been planed..
MD(mad dog)

 

[Telly]

Ya, it does sound confusing. Suppose the PO could have made some changes and mixed and matched. Your certainly on the right track by making sure you get the right gaskets for the appropriate year head/block.

Terry

P.S. Roger Williams book "How to Restore TR5/250 & TR6" has a section on the different heads and blocks.

 

[ALLAN]

OK. Its an early model head that I thought was a late model head, I had it ported, polished, and shaved the I.D under the valve cover reads BIL , it is on my new motor ready to be installed. Is this the wrong head to be using or is it a good one ??------Also I have never seen a clear definite reason why the circle B heads are supposed to be better--why are they better?

 

[bobh]

The wide port head was used on the PI cars. That implies they are better. You can also read this article by Chris Witor to gain an understanding of the better flow characteristics of the 219016 head.
https://www.tr6.org/cylheads/index.html
The 219019 head is the low compression version of the 219016. The 219019 was used on the late model US spec TR6. I don't know when it they started using this head. I suspect it came with the introduction of the EGR valve.

BOBH

 

[ALLAN]

The circle b head has narrow spacing (its almost always said thats the best head) and no egr hole. My 71 head has wide spacing and no egr hole and the head installed on the my engine has narrow spacing and no egr hole, so I do not have a 219019 head. But this still leaves the question about the circle B head