Engine: 7hp, 1932

[Forumadmin]

Driven plate removed showing clutch plate.
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[Forumadmin]

Clutch plate removed showing pressure plate.
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[Forumadmin]

Pressure plate removed showing springs & flywheel.
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[TTHORN]

" 8 ' 1937
Re Cylinder head replacement.
I have the information regarding the tightening sequence after replacing the gasket/ head but can anybody pass on information about the required torque.
Also torque cold ? torque hot? and check plus further torque, if at all ,and if so after how long??
Also.
Am I likely to strip a thread ??

[Forumadmin]

I will leave this to those more experienced with these pre-war engines...but I would say there is no real guide. Torque figures were not used in those days. With old engines the torque used depends a lot on condition, mainly of the block and the stud fixing. If helicoils are fitted then you may be able to reach close to what the stud itself will stand. The gasket type governs how the torque is applied and what the bedding in method is. The flatness of the block and head and liner height will govern if anything will strip or crack.
Just take a lot of small increments . Take a lot of care and feel sympathetically how the metal is coping. Any sudden increase or decrease in the torque being applied shows something is wrong. A long wrench used with a finger is better than a short one with full force of the hand to gauge the torque.

[Keith Clements]

I am debating whether to move the last couple of posts in this Topic to the Technical/pre-war forum.....
This is effort for me to do, not a lot but too many postings in inappropriate places and it becomes a chore.

Julian, whose personal album this conversation is in, may like to comment.

[julian]

Hi Keith
I'm fine with the posts been moved to the technical/pre-war forum. As you say its better to move it now before the post expands.

[Forumadmin]

Please continue discussion here

[Keith Clements]

I should add that the threads on the studs and nuts should be cleaned with tap and die. They and the washers should be oiled prior to assembly to ensure smooth torque up. There might be some discussion on the desirability of oiling or using copper grease on exposed studs because it would alter torque values. Note that on studs close to oil or water ways that are inside the tappet cover (on a Jav/Jup) a ring of solder is applied as a sealant under a washer with a chamfer.

If studs are removed they should be replaced at a torque 40% of the stud's nut preferably with a threadlock for studs (Loctite 269 ) to prevent rotation.
https://jowett.net/Parts/TechNotes-Part07-CylHdGskt.htm

[Tony Fearn]

....the required torque.
Also torque cold ? torque hot? and check plus further torque, if at all ,and if so after how long??
Am I likely to strip a thread ??

Hello Tony.
Have a look at the attached scan of a drawing I made for another pre-war owner.

Barry 2.jpg

I've found it important to use a new set of cylinder head nuts when replacing the heads. You can see from the sketch how the bottom of a previously used nut splays outward, and when you give it the final turn, it will just go round and round and not do its job.
Use a flat thin washer under the nut.
Tighten the head studs using the sequence when cold, until they're up tight when using a normal ring spanner.
I've never used oil or grease on the threads/nuts.
Cleaning up the studs as KC suggests is good practice.
After running the engine until it's warm, tighten them all again using the same sequence. You'll get a bit more movement on them.
Perceived wisdom suggests using K-seal in the radiator water when all is finished, but use your own judgement.
Hope this helps.
Tony.

[David Morris]

Hi Tony,

On the subject of tightening torques, I liked the description given by Jowett's themselves in the maintenance manual for the WW2 Stationary engine.

They used the designation of 'TIGHT' and 'DEAD TIGHT' when telling the mechanic what to use, which I think nicely describes what to apply? This was probably around 15ft.lbs and 30ft.lbs. Obviously no torque gauges used then in Idle!

All the best,

David

[Keith Clements]

Make sure the nuts you are using are high tensile and not the cheaper ones. https://www.namrick.co.uk/acatalog/Home ... ts__1.html
Also of the correct height, on JAv JUp the nuts around exhaust are higher than normal.

[Tony Fearn]

Make sure the nuts you are using are high tensile and not the cheaper ones.
Also of the correct height, on JAv JUp the nuts around exhaust are higher than normal.

Hello again Tony.
Jowett Car Spares should have a set of the required size/shape pre-war cylinder head nuts.
As you can see from my sketch, they are of special design allowing easier use of the spanner when tightening.

I've always sparingly used gasket cement on the gaskets, but others say they never do this.

Hi David,
I too love the old terminology and phraseology of the Jowett instruction books.
Dead tight is obvious, but I've never seen the next designation -OOPS- written down, which occurs after the stud has sheared off due to excessive force, or just age!

Tony.

[David Morris]

Hi Tony,

Well yes, it could be 'OPPS', or perhaps something a bit more salty?

Best regards,

David

[ian Howell]

On my 1930 Long Four there are three different lengths of cylinder head nuts - all of the general shape as drawn by Tony.

They are fitted in pairs, longest at the top, then middle length, then short ones at the bottom (I think - I am in Wales and my car is in Sussex!).

This seems to be to clear the recesses in the heads and possibly to permit turning of the engine when removing the opposite side head nuts.

Any comments?