1850 head

[Henk]

Last week I purchased a used 1850 cylinder head. This afternoon I tried matching the Payen head gasket (NOS). I've two questions, see the image below.

The head's galleries do not always match the head gasket holes. It's not just a small difference in shape: holes but no galleries and galleries but no holes. Comparing my image to an image Jeroen took several months ago, his cylinder head has more water(?) galleries than mine.
Do I have the wrong head gasket, do I have the wrong cylinder head, or is it just a minor upgrade during production but exchangable?
The head gasket I received is NOS and it shows, the metal rings around the cylinder bores show some surface rust. Is it possible to remove it or does this weaken the gasket: should I bin this HG and buy a better preserved one?

Mine:


Jeroen's:

[Jon Tilson]

The heads changed at some stage when the TR7 was brought in, with larger exhaust valves.

Early heads have a slot under the inlet ports on 3 and 4 cylinders and smaller exhaust valves.

Jonners

[Henk]

Aha, thanks for clarifying Jon.
This means altering the head gasket according to the galleries?
Or maybe a better idea to keep the current (=old design) head. Any pro's or con's at using the newer design in stead of an older head?

[Jon Tilson]

Depends on what carbs you want to go with....

On balance the later head with bigger valves would be my choice with SU's, but the early head with strombergs
works quite well...

Jeroen should also add his wisdom...


Jonners

[Henk]

The car will get SU HS6 carbs.
I'll contact Jeroen for further advice.

[Jon Tilson]

Then use the TR7 style bigger valve version...would be my advice.

Jon

[AlanH]

Are there two types of gaskets?

I have had a look and can only find the one?

[Carledo]

AFAIK this head is perfectly correct and so is the gasket. the holes in the gasket around the 2 middle cylinders are smaller to restrict water flow nearer the water pump and let the water flow freely at the back of the engine which runs naturally hotter. Its like that for a reason, don't mess with it!

Steve

[Henk]

Thanks guys, I'll go further preparing this head for some skimming.

[sprint95m]

The car will get SU HS6 carbs.
I'll contact Jeroen for further advice.

Henk,
why the HS6 carbs?

Would it not be better to go for fuel injection since the appropriate parts are available for LHD cars (sourced from a USA version of the TR7)?


If I was you, I would ask Jeroen about the TR7 EFI set up. He fitted this to his 1850 a few years ago.



Ian.

[Henk]

Because I love SU's!
In my opinion a carburettor suits the age of the car better than an EFI, I find it to modern.
I choose the HS6 to suit the Kent DMS1 camshaft.

[Henk]

Contacted Jeroen, he confirmed that the HG is correct. He suspects that I'm using the old type head, with smaller exhaust valves though.
The blocked galleries are correct, the water has to be transported through the block to the rearside of the engine, then enter the head and flowing back to the front.

Additional question about valve timing.
The stock camshaft has these details: inlet valve opens 16° BTDC and closes 56 ABDC. This means that the camshaft has a duration of 16+180+56=252°.
Full lift is then reached at (252/2 = 126°, 126 - 16 =) 110° ATDC. Is my calculation correct?