Head studs

[tim wood]

Hi all,
As part of my cylinder head overhaul I’ve removed all of the studs from the block so that I can throughly clean the surface and prepare.
This is a short stud block.
With all of the studs out and unfortunately I didn’t note which position each came from, I can see that that I have the 4 longer studs that accommodate the lifting brackets.
I understand that one of these should be a shouldered stud but I can’t see it.

Seems strange?
I can check for fit into the head once it comes back from rework but until then any thoughts.
Tim

[Simonpfhc]

Hi Tim,

The shouldered stud (dowelled) should be the second stud back from the front on the left hand side. You can see it the in attached picture as it is the only stud I didn’t replace!

[tim wood]

Thanks Simon,
The picture is clear,
My issue is that I have 4 of the longer studs none of which show the shoulder !

Tim

Once I get the block cleaned up I’ll insert them and post a picture

[tim wood]

First time I’ve got an image to work !

These are my 4 longest studs

[christopher storey]

Tim : just buy a single shouldered stud ( it is a different part no from the rest ) and place it in the no 2 position ( i.e 2nd from front ) on the left side . They are not very expensive

[tim wood]

Not a bad idea Christopher, I’ve got a few other bits to order

[abowie]

[tim wood]

Thanks Andrew, I’ve got that.
My question is why don’t I have a shouldered stud?
My only thoughts are that the head has been off before and someone has used an incorrect stud.
On another post I mentioned that the camshaft bolts did not have wire locking which possibly adds weight to the thoughts that the head has been off previously.

Thankfully the pistons and bores seem in good order and the head is being overhauled following which all should be good
I’m running a die nut along the studs and am sure that I will need to replace a few.

[abowie]

the head has been off before and someone has used an incorrect stud.

Sounds like the logical explanation.

[Allrand]

Check if the hole the cyl head at that position is reamed out to a depth to accommodated the shouldered stud. A non reamed out hole won't accept a shoulered stud. Don't ask.

[Simonpfhc]

Just to add a slight word of caution…..

When I bought a brand new dowelled head stud it did not fit into the recess in the block as the diameter of the dowel was too big. The original dowelled head stud fitted perfectly, so I kept it. That is why in my picture in my first reply all the other studs are brand new but not the dowelled stud.

If you have the same issue, you will need to skim down the dowel slightly.

[tim wood]

Hi Simon,
Thanks for your reply.
Could let let me know where you sourced your head studs.I’m in a frame of mind to replace all of mine.

SNG ?

Some of the threads look knackered anyway.

Thanks
Tim

[Simonpfhc]

Yes, SNG.

[tim wood]

The mystery thickens,
For some reason I decided to check the length of all studs.

The short studs seem correct @163mm whereas the 4 long studs are 170mm. I understand that these should be 173mm.
So as I have to purchase the dowelled stud it now looks as though I may also be in for the other 3 long studs.

I’m of the view that the “missing” 3 mm is needed and thus important.
Does anyone have any thoughts?

(As an aside the head cone off for a general overhaul not related to gasket failure)

Tim

[tim wood]

I think I may have solved the riddle of the 170mm studs.
They are part number C42355 used on some XJ6 engines with the pressed steel lifting bracket. This bracket is thinner than the cast unit hence a shorter stud is used.
My head is original to the block so either the studs have been changed or were used when the motor was made.
I think that the head has been off before ( no lock wire on the cam bolts is an indicator) so my guess is that these have been changed at some time. This also explains which they show much less discolouration than the other (short) studs.
I’m not prepared to use studs which I know are not correct
So it looks like another order to SNG.


Tim

[tim wood]

So the journey of discovery further unfolds.
I’ve been cleaning the block and piston tops. All the pistons are original and standard size. I can see that number 5 piston has some small dents in the surface which leads me to believe that this was the reason why the head has been off before.
The bores seem sound and I can see the cross hatching. I’m happy that I can just clean this all up.
As an aside I’ve had to rotate the engine to access to piston tops, in doing so I now know that the previous TDC position (with the cam timing tool fitted) was ever so slightly out.

Tim

[mgcjag]

Hi Tim..just to remind you dont forget that two revolutions of the engine to one rev of the dizzy..so you want your rotor arm pointing to the correct position befor fitting the head.....Steve

[tim wood]

Thanks Steve,
I’m on EDIS.

Why do all jobs turn out to be more than expected!
Tim

[tim wood]

I understand that it’s a good idea to seal the head studs when inserting into the block.
( short studs block )

Does anyone have thoughts on this and what sealant would be used?
Locktite maybe?

Tim

[abowie]

Permatex 56521 Thread Sealant is what we use.