Head studs

[Keith Clements]

Prompted by a discussion with Bill Lock and Richard Gane at the NEC I learnt there were different lengths of head studs because there are different thicknesses of head. (Even before they were shaved)
So here is my motley selection.
First the five different types (assuming the one at the water inlet has been extended)

Then the different sizes of lower studs.

Then of the upper studs

Then the centre stud oil feed.


Putting a ruler to the longer of the two sorts - all 3/8 BSF thread all top thread length first
No 1 178mm 17 mm 23 mm
No 3, 5, 7 125mm 18mm 22 mm
No 2, 6, 8, 9 106mm 16 mm 23mm
No 10 180mm 19mm 34mm then gap 24mm then 26mm at bottom or thread all 84mm
No 4 Oil feed bolt 3/32in hole drilled to depth 38mm then radial hole to open up. End turned down to 7mm for 9mm and finished off rounded. 23mm thread after turn down and at top end. Flat from 37mm from bottom to 12mm from top to make 5/16 in thick.

[Keith Clements]

Having been given Sam Glover's block (that is from his Jav) at the show to inspect I duly had a look on Monday.
This was my scribbled report

.nearside Stud 10 and offside stud 7 sheared... all others with good thread
Cylinder 3 2 4 liners seal corroded ..may just seal but would benefit with some build up
All lower gasket faces corroded would benefit with some build up
No 4 sude gasket seal scratch.. use plastic metal to fill.
Threads all good on ___Oil sump and splash pan. Timing cover and oil pipe ..clutch cover

Camshaft and main bearing faces good. All locators present.
Joining faces good free up and put back in the dowel cylinder.

I have blown out loads of sand but all oil ways should be cleaned and oil plugs replaced.
I have tapped all head bolts and am fixing sheared studs. Just need a long 3.8 bsf tap.
All other threads should be tapped and died.
Suggest lengthening or helicoil oil filter bolt holes.

So with the next task to check for porosity I set about removing the broken studs. I ordered a long 6mm end mill and long 3/8 BSF tap from Tracy tools .

The milling machine was aligned and this is the result. I only have one old rusted extended bolt to put in so cleaned up with a die.


All other stud holes were cleaned out with tap and a selection of old studs cleaned up.



The liners were set up with shims and the head put on with a rubber gasket.
The water transfer and water drain sealed and the compressed air input and gauge output clamped in place.



Unfortunately I could not get the system to hold air so will have to find another day to investigate.

[Keith Clements]

Sorted out the head studs again and measured difference between long and short in mm.
There is some variation of 1 to 2 mm between each type of stud.

Oil 129/124
centre 144/140
top 123/117
bottom 105/101
water transfer 61 with 2 x 16mm thread

[Keith Clements]

After vibration testing the engine for the SA I did the other of Sam's blocks.
Removing the stud is not that easy. I find drills wander so after centring the mill head, a 5mm pilot hole was drilled then a 6mm end mill was sent down the hole to re-align it. I did not have a mill long enough to go to the bottom of the second hole. So a 6.5mm drill was then sent down the hole to see if the hole was aligned properly. It was out by 1mm as you could see when it came through underneath. An air saw was used to cut the rusted stud close to where it entered the aly again. Then the rusted part was knocked out. The end mill was then used to align the hole. It needed a few passes to get the hole vertical. A 7.5 mm drill was sent down to see if it aligned with the cut off bottom part of the stud. The stud end was filed at a slight angle to bring the centre of the drill back into line. A 6.5 mm pilot hole was drilled then after checking this came out the bottom of the hole correctly the 7.5mm drill was sent down.
You should really use a 8.3 mm tapping drill for 3/8 BSF but I wanted to see if I could clean out the old threads. So I then used a very well tapered tap No1 in the first part of the thread. Then a no 2 and then the long tap which would go through to the bottom part of the thread. Job done.