The Triumph Dolomite Club - Discussion Forum

Is it possible to fit a TR7 head to a 1850 engine block?

I found some opinions in the archives but no consensus. Some say it won't physically fit, others speak of compression ratio loss due to a bigger combustion chamber in the TR7 head?
I'm after this one:
http://www.2dehands.be/auto-onderdelen- ... nt=234x104

Did I miss the conclusion on this topic?

They are the same. Well late ones for TR7's and 1850s have larger exhaust valves and no slot under
the rear inlet ports but apart from that it will fit perfectly.

Jonners

They are totally different.

If you would fit a tr7 head on an 1850 you will end up with a compressio ratio of about 1:6.

Jeroen

That's no option then.
Thanks!

Jeroen wrote:If you would fit a tr7 head on an 1850 you will end up with a compressio ratio of about 1:6.

Yeah, but at a CR of 6:1, it would probably run on some pretty low octain fuel, possibly paraffin or ATF (jet fuel, not auto-transmission fluid).

I remember when I was at tech collage in the 70s (doing motor engineering, after I discovered I weren't cut out for civil engineering, and before I found out that electronics was that easy) we had a Dutch lecturer (whose name escapes) who reckoned he'd run cars on wood smoke during the war. If I remember, he said that knocking was a bit of a problem with that. So that might work well at 6:1.

Thing is, thought, the stove that heats the pine, and generate the fuel gas, takes up all the boot space.

That, and you really need a chauffeur! So perhaps it's only an ideal fuel in Stoke-on-Trent.

Graham

MMMMMMMMmmmmmmmmmmm or perhaps a nice big turbo

Yes that idea crossed my mind!

Looking at a TR7 and a late 1850 head I am struggling to see the difference.....
The rear heater outlet is about all I can see and that is interchangeable...

Jonners

Jon Tilson wrote:Looking at a TR7 and a late 1850 head I am struggling to see the difference.....
The rear heater outlet is about all I can see and that is interchangeable...

Jonners

Combustion chamber cc's ?

Tony

I have just read posts on TR7 head on a 1850 dolomite,i recently changed my inlet manifold gaskets on my77 dolomite and noticed that there wasnt a slot under the rear inlet ports, do i have a TR7 head on my car, are there any other identifying features i can look for. My engine doesnt run smoothly at all despite balancing the carbs resetting the timing and fitting an accuspark ignition unit. The running can be best described as "heavy" and icant get a decent idle. Compressions are equal and every thing checks out ok. Should i consider changing the head for an 1850 type, but would welcome your views first.Thanks Tractor Boy

tractor boy wrote:... there wasnt a slot under the rear inlet ports, ...Thanks Tractor Boy

Apparently only early 1850s had this slot - none of the three heads I've used in recent years had a slot here, but the gaskets are cut for the slot just in case.

Thanks Bill the joys of owning a dolomite i learn something new every day!!. Tractor Boy

Googled some heads.

The upper is an 1850 one and the lower two tr7's.

The middle has a bigger cut out around the valves so a bigger combustion chamber. The lower is a low compression and this type i have two which was with the fuel injection sets.

Jeroen

The 1850 got the larger exhaust valves around the time the TR7 was introduced.

Anyone got a TR7 parts book?

Jonners

Just a question, but what CR would you likely get the other way around - 1850 head on a 2 L TR7 block and piston set? Possibly, as an alternative, with the US spec low compression TR7 pistons.