What Thread Insert Do I need?

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What Thread Insert Do I need?#3829

By Tomshayes - Mon Jun 30, 2014 12:39 pm

- Mon Jun 30, 2014 12:39 pm #3829

Hi All

Can anybody tell me what thread insert kit I need for repairing the rocker box stud threads in the cylinder head on my 1991 350.. I think it's 1/4" BCy... But not sure!

What Thread Insert Do I need?#37084

By PeteF - Mon Jun 30, 2014 1:52 pm

- Mon Jun 30, 2014 1:52 pm #37084

More likely to be BSF on the engine.
Same TPI (26) unfortunately so that doesn't help to identify it. The thread form is different so you should use the correct one really.
If you have the facility to measure the existing stud thread,
All the information is here.

Classic C5 Euro 4 at the moment.
Also CBf250.

What Thread Insert Do I need?#37085

By Tomshayes - Mon Jun 30, 2014 2:16 pm

- Mon Jun 30, 2014 2:16 pm #37085

Hi Pete

thanks but that's the problem, I have no way of measuring the thread other than by eye at the moment.

What Thread Insert Do I need?#37103

By simon - Tue Jul 01, 2014 8:01 am

- Tue Jul 01, 2014 8:01 am #37103

1/4 cycle mos def. 26 tpi at 60 degrees thread angle. Which differs from 1/4 BSF which is also 26 tpi but 55 degrees thread angle.

What Thread Insert Do I need?#37111

By Tomshayes - Tue Jul 01, 2014 6:10 pm

- Tue Jul 01, 2014 6:10 pm #37111

Cheers Simon..

I just happen to have that very Helicoil Kit.. Much appreciated!

Tom