Simple one for the engine builders!

[JJDraper]

I have just taken the head off my +2 twincam and decided to do something about the dodgy threads on the thermostat housing lump. They need helicoiling to sort them out, but I am not sure what thread to ask my machine shop to fit! The housing was held in place by one bolt & one stud both of indeterminate origin (one was possibly an exhaust stud). The original threads are still visible but not in good condition.

Any answers?

Jeremy

[NickD]

5/16" UNC

[JJDraper]

Thanks for the speedy reply!

[cliveyboy]

Hi Jeremy
How you doing.
We talked about the threads when you came over to visit recently.
Give me a call/email as I reckon I can fix that for you fairly easily and quickly in situ without taking the head off.

Clive

[JJDraper]

Hi there, too late! Head is off due to head gasket failure. Too much thrashing along motorways..... Still it lasted 30k miles.

I have now had a closer look at the threads and only the top quarter inch has gone, the rest is OK, allowing a 5/16th stud to screw into the remaining thread quite well. I think I might fit studs instead of using bolts. Anyone know any reasons why I shouldn't do this?!

Jeremy

[tower of strength]

Hi there, too late! Head is off due to head gasket failure. Too much thrashing along motorways..... Still it lasted 30k miles.

I have now had a closer look at the threads and only the top quarter inch has gone, the rest is OK, allowing a 5/16th stud to screw into the remaining thread quite well. I think I might fit studs instead of using bolts. Anyone know any reasons why I shouldn't do this?!

Jeremy

I think you may have trouble removing the housing at a later date due to gasket sealer and any weeping onto the studs.

Mark

[john.p.clegg]

Jeremy/Mark
I've had studs in mine for years now,don't know why lotus didn't do it that way,a lot better IMHO....

John

[JJDraper]

Thanks for the comments and advice. I have decided there is a risk to using studs (housing could get stuck, but I remove the housing twice a year to change the stat - summer/winter) and a risk to using bolts (crossing them or pulling the remaining thread). On balance, I will go for the studs, perhaps stainless if available from any suppliers(?).

Jeremy