Which head gasket?

[iani]

I pulled my head off this morning and was surprised to find that I have a recessed block head gasket, the engine number is CP51930HE and I thought this was well before recessed blocks came in. I've attached some pics, what gasket should I use?

[JochemsTR]

Ian,

the number on the block could have been altered. Maybe to get some “matching” numbers. 

If the block is recessed, you use a recessed gasket. 

Jochem

 

[peter.goreham]

Hi Ian,

In the early 90s I was restoring my TR5. As part of the engine rebuild I was having the engine block rebored at a local machine shop.

The owner of the engineering shop, who’d previously owned a TR6, recommended recessing the block to take the later gasket.

I took his advice, so like you I have an earlier block that takes the later gasket.

Worth checking for a tag on the end of the gasket before you order spares regardless of the engine number!

Peter

[astontr6]

1 hour ago, peter.goreham said:

Hi Ian,

In the early 90s I was restoring my TR5. As part of the engine rebuild I was having the engine block rebored at a local machine shop.

The owner of the engineering shop, who’d previously owned a TR6, recommended recessing the block to take the later gasket.

I took his advice, so like you I have an earlier block that takes the later gasket.

Worth checking for a tag on the end of the gasket before you order spares regardless of the engine number!

Peter

This question seems to come up a lot! BL went over to the recessed block design due to problems with the original head gasket/block design. The head gasket failure on the original blocks was caused by the block distorting along with the cylinder head and cracking between the valves. I worked on this problem over 45 years ago when I was an apprentice at Coopers also known as J Payen who made all BL's gaskets. As your block is recessed, in my view, only use the gasket for that type of block as the fire rings are thicker to take up the extra space and only use a torque spanner when doing up the head nuts and retorque after 500 miles? Engineering wise the later blocks/heads after mid 1972 are the better ones to go for, if looking for a replacement, as they have been strengthen.

Bruce.

[iani]

Thanks chaps, I'll order a recessed gasket, I already have the earlier one here.

Ian

[BlueTR3A-5EKT]

As Cox and Buckles & later Moss we sold new blocks and built numerous engines with new un-numbered recessed type blocks for 6 cylinder Triumphs.

As stated above yours could be a number matching exercise using a replacement block after perhaps a crank thrust washer failure.

Cheers

Peter W

Edited April 20, 2019 by BlueTR3A-5EKT

[iani]

From what I've read today, the presence of a strengthening rib on the lower end of the manifold side is a sign of a later block. Having checked my block, the rib is there, I take it the theory of this having been an un-numbered block given an old engine number is probably correct. Thanks gain chaps.

Ian