MK1 head stud options

[camstevens]

Hi All
An interesting problem (well, not really a problem, as such) to solve. I'm in the process of refurbishing an old head...generally pretty sound; it has been fitted with 1/2" BSW to 5/16" BSW mild steel reducers, with original 5/16" studs screwed in. I have torque tested the fittings and they seem fine. I wish to upgrade the studs to SS, and I have a set of ACME 3/8" SS upgrade studs I would like to use, if I can.

I see my options being;
1. retain the mild steel inserts and purchase a set of 5/16" SS studs, or
2. have a set of SS 1/2 BSW to 3/8 BSW inserts made and utilise my 3/8 studs, or
3. have a set of SS 5/8 BSW to 3/8 BSW inserts made and utilise my 3/8 studs (and drill / tap head for 5/8).

Option 2 would be the ideal (less head work), but at Major Diameter of 0.375 for 3/8 BSW and a Minor Diameter 0.410 for 1/2 BSW, I'm not sure if that leaves enough meat between the threads?

Also a rather interesting repair on the exhaust V/V seats........probably effective though.

Cam

1/2 TO 5/16 insert

Dotty!

[camstevens]

Sorry, read chart incorrectly....Minor Diameter for 1/2" is only 0.393

[david.anderson]

Cam
Stainless nuts on stainless studs do not go well unless a good lubricant/anti-seize is used. However as these are head studs the heat may destroy the lubricant over the years and when it comes time for removal the nuts may gall and strip. Ask me how I know. Not such a problem with steel studs and stainless nuts or vice versa. The stainless nut is what will be seen so I would just use stainless nuts or make sure the anti-seize is long term and heat tolerant which some anti-seize are not.
The centre punching around the valve seat should not be trusted as it will only tighten the outer surface and the seat will quickly come lose in the head. The only safe way is to fit a slightly larger o/d seat.
David

[JohnnyBeckett]

hi, have you been onto the people who make recoil and see if they do a recoil to fit the size you need to fit the standard size studs

[camstevens]

hi, have you been onto the people who make recoil and see if they do a recoil to fit the size you need to fit the standard size studs

Hi
I was warned off using any form wire wound thread repair as apparently they unwind with the heat...Recoil do have a "Keensert" product, which are solid units but appear to be all metric.

I also have 3/8 upgrade studs from Acme, so any insert would have to use the existing 1/2 BSW socket (or larger if drilled out.

I see from other chats the Paul Wiggins had threaded in and pinned 6061 solid plugs (slightly proud), planed the whole surface flat, then redrilled and tapped for the new studs. This seems a nice clean way of doing it to me.

C

[JohnnyBeckett]

hi, i use UNI-THREAD for all my thread inserts they do all imperial and metric threads he has got me out of trouble a few times he is very helpful and knows is job and doing new inserts

[herman.noort]

Hi Cam, I wouldn't worry too much about SS nuts becoming stuck.
However, NEVER use STEEL inserts in an aluminium head!!
Steel has an expansion factor of about 8.8, and aluminium has an expansion factor of about 22!!
Best is to use a strong Bronze alloy for the inserts, I used Phosfor Bronze, which has an expansion close to aluminium.
Use coarse thread on outside of insert.
Go for the biggest diameter SS studs into the new bronze head insert.
Use low torque when tightening when the engine is cold, as per club/Bruce Longmans instructions.
Valve seats are also best made of a bronze alloy, like Cosybro.
If you mail me direct on herman@hnoort.nl, I can send you lots of info & photos about the notorious MK1 head.
Good luck!

[camstevens]

Hi All
Picking up on this thread again.......if I am using modern Otto type gaskets, would increasing the adaptor OD from the current 1/2" OD to 9/16" cause any material consequence to the gasket function? In any case would skim the head mating surface after fitting adaptors to minimise surface issues.

Cam

[nevhunter]

Consider Duralumin Inserts. Strong and near Al rate of expansion Avoid decking the Block if you can.If you are good with a Bellied file do it that way carefully. Use a flat surface plate and Blue to check the flatness. Some use Plate glass. Nev

[camstevens]

Hi
I just reading the Mk1 Otto gasket fitting advice again to see if there was any mention of using copper sealing washers on the 4 rocker box studs. The advice suggests using copper sealant under the 3/4" load washers.

Has anyone ever used copper sealing washers instead? I didn't see that suggsted as an option, so not sure if a bad idea.

C