Two more 1850 head questions.

[MIG Wielder]

Hello All, Thanks for your advice so far. Couple of other questions if you can help please.
* In the 2nd photo what are the 2 extra tapped holes for above cylinders 3 & 4 please ?

Edit > Answer 14/4/17 : The version of the Dolomite head with those 2 extra tapped holes comes from a Saab 900. Thanks to Jeroen for that.

* In the 1st photo it looks as if the top right tapped hole for the rear-of-head-plate has got a tapped insert in it . Rather like a helicoil, only larger. What is this called please ?
I know on the Sprint there is a measurement you can do to determine if the cylinder head has been skimmed before. Is there a similar measurement for the 1850 head please ?

Thanks,
Tony.

[new to this]

Tony

in picture one, that looks like a time sert

Dave

[MIG Wielder]

Hi Dave, Thanks very much for that. I hadn't heard of this system before.
It looks like an alternative to the Helicoil thread system readily available in the U.K,
http://www.timesert.com/
I can see a positive advantage where the thread is in water or oil as it seems to seal nicely.
Cheers ,
Tony.

[tony g]

I thought time sert too but Ive not seen one with the 2 cuts in the head of it before.

Tony

[soe8m]

A saab 99 head. The insert is a plug that plugs the oil bore.

Jeroen

[DOLOMITE 135]

Edit > Answer 14/4/17 : The version of the Dolomite head with those 2 extra tapped holes comes from a Saab 900. Thanks to Jeroen for that.

To clarify, is this is a SAAB head because of the 2 extra tapped holes, or is this version of the head casting shared with a Saab 900?

[soe8m]

These holes are used at a saab to hold a defroster hose from the exhaust manifold to the airfilter box. Saab had this engine fitted some years before they were fitted to 1850's. I'm not sure of the very early 1850's if they shared the casting. The 1850's I had never had these holes and the oldest I had was a 1973 one.

Jeroen

[DOLOMITE 135]

Following on from the comments above about 1850 / Saab cylinder heads I decided to inspect the cylinder heads I have, as I have not previously noted any differences. As a result of this investigation I have identified that I have two types, three (including the one on my car) with the 2 additional threads to hold the Saab defroster hose (which I will call type 1) & two without (which I will call type 2).

Comparing the two types I have noted the following:
Type 1 has the above mentioned additional tappings, type 2 have small additional untapped lugs just above the exhaust ports.

Type 1 has a different profile to the rear of the head (to the left of the water transfer mountings in the photos below) and a different water transfer housing (type 1 up to 76 water transfer housing, type 2, 76 on water transfer housing).

Type 1 and 2 have differing oil / water galleries on the back of the head necessitating the different water transfer housings.

Type 1 has an addition slot under the inlet ports for cylinders 3 & 4.

Types 1 and 2 have a slightly different profile to the rear most water gallery on the face of the head.

I have not measured the valves so I do not know if these differ also.


I note from James467 thread and others that the addition tapped lugs are visible on the earlier cars, such as:
viewtopic.php?f=19&t=32242&start=15

So do we have a pre 76 head which shared a common casting with the Saab head, and a revised head for 76 on requiring in the new water transfer housing and losing the Saab lugs?

[soe8m]

The one with the lugs above the exhaust ports are for the egr on a tr7. I cannot see the chambers that well on my phone but the tr7 has a bigger chamber and I thought only tr7 heads have these lugs in their casting. I'm not sure if your type 1 and 2 are pre 1976. Maybe the stromberg versions. Saab didn't use these head's from 1972 on. Maybe that is the revision date.

Jeroen

[soe8m]

Just checked. My 1850 head has also egr lugs.

Jeroen.

[DOLOMITE 135]

All the combustion chambers look the same to me on my heads, maybe the heads were redesigned for the TR7 and the improvements were incorporated into the 1850's in the mid 70's?

[sprint95m]

Further to Jeroen's observation….

So do we have a pre 76 head which shared a common casting with the Saab head, and a revised head for 76 on requiring in the new water transfer housing and losing the Saab lugs?

Triumph produced two 8 valve slant four cylinder heads for the 1850 engine.

The early version has a coolant transfer slot under inlet ports 3 and 4
(said transfer slot is used on the Stag but not on a Dolomite).
The later (1850HL) is a quite different casting without the coolant transfer slot, a different transfer housing
and also larger exhaust valves .
(Complete heads are interchangeable. The EFI inlet manifold doesn't fit the early head though.
TR7 heads are not interchangeable.)



Triumph built engines for Saab for the 99 between 1967 and 72.
These were 1709cc for a time before the 1854cc was introduced.
After 1972 Saab started to build their own engines, modifying the design a lot as they went to the 99 turbo
and then 900 range.

Generally speaking, the interchangeability between the 99 engine and Dolomite 1850 is only for 99s to 1972 and Dolomites to 74.



Ian.

[Jon Tilson]

One further difference on TR7 heads is that the rear transfer housing has a heater pipe outlet, which is annoyingly slightly larger than
dolomite heater pipes.

Other than that the wisdom goes with what I;d always believed, early and late heads. Hadn't noticed the tapped holes on early ones before now.
So those holes always go with the slot and smaller exhaust valves then.

So how much different is a TR7 head Jeroen? Is it just the combustion chamber size?

Jonners

[DOLOMITE 135]

Looking at Rimmers' web site they refer to 4 gallery water jacket (my type 1 above), and 3 gallery water jacket types (my type 2 above).
The 4 gallery water jacket is to 76 and the 3 gallery water jacket 76 on.
They list the same exhaust valves for both types, but differing inlet valves. The 4 gallery water jacket type having the same inlet valves as the Stag, and the 3 gallery water jacket type sharing its inlet valve with the TR7.

[soe8m]

Here the difference.

The upper is my 1850 head and the lower a random tr7 head. The combustion chamber is significant larger. I'm using this 1850 head on a 2 liter engine

Jeroen