Cam Head Exhaust - Stripped Female Thread - Helicoil

[Joe K]

Hello All,

The number one cylinder exhaust on my sandcast cam head is stripped and I need advise on how to fix it.  This is where the exhaust flange connects to the head.  Would a helicoil work and if so, how can I determine what size to use and or what metric size is the flange screw?     Does anyone have a couple spare helicoils I could purchase?  I know I would need the tool to insert it.

This may not be the proper fix, but seems like the easiest without taking the engine out of the frame, removing the head and taking it to a machine shop.

Thank you,
Joe K.

[markb]

I assume this is the flat head flange screw.  That would be a M8 x 1.25 thread.  A helicoil should work just fine.  I've repaired several stripped out threads with good success.  I would recommend buying a kit.  Then you have the proper tap, tap drill and tool.  Here's a link to one source:
http://www.mcmaster.com/#catalog/118/3284/=k06rb3
Part number 91732A951 might be a good choice.  It has some different insert lengths.  The 12mm seems like a good choice.  It depends on how deep the hole in the head is.  You may want to consider getting a bottoming tap (part number 91709A555) or grinding off the tip of the plug tap since it's going in a blind hole.  You just need to make sure the hole is going in straight.  Having someone eyeball the drill from the side while you look at the top would help.  Good luck.

[Steve Swan]

I like Timeserts.  The Timesert is just as easy to install as the Helicoil.  The Timesert is an actual insert that locks in the hole.  With heat and cooling, expansion and contraction, the Timesert would be my choice.  Certain metric sizes of Timeserts and and the installation tools are available at my local Autozone.  Am sure out there in Cal, you should have any number of  sources for these.  

http://www.timesert.com/

[Joe K]

Thank you, Mark and Steve.  After seeing the Time-Sert video, I think I will try that option.  I will let you know how it comes out.  And yes, Mark it is for the flat head flange screw.

Joe K.

[markb]

I agree, the Timesert is another good option.