Heli Coil For Exhaust Bolts Help on 1961 Cadillac

[Jack Miller CLC# 24441]

Hi All,

I found that whoever had my car before me stripped the bolt holes in my heads that hold the exhaust pipes. I need to drill new holes and then tap in heli coils. My problem is that I can't get a drill in there to make the new holes. Do they make a drill adapter with a 90 degree angle? Or do I have to remove the motor or intake & head to do this. I originally rethreaded the holes to metric, it worked fine, but after removing the bolts, because I had to put in heli coils in the exhaust pipe end of the exhaust manifold (by the heat valve) the are now weak again in the center 2 bolts.
Has anyone here done this in the motor in the car and can advise?

Thanks
Jack
1961 Cadillac

[The Tassie Devil(le)]

Hi Jack,

From all my experience, you will need to remove the heads to drill, tap and insert the Heli coils.

Or, it could be cheaper to simply remove the engine and do the task.   This way, you won't need to replace the Gaskets and the like.   Nothing worse that a disturbed engine.

Plus, if some are needed, I would be replacing the lot.

Bruce.

[J. Gomez]

Hi All,

I found that whoever had my car before me stripped the bolt holes in my heads that hold the exhaust pipes. I need to drill new holes and then tap in heli coils. My problem is that I can't get a drill in there to make the new holes. Do they make a drill adapter with a 90 degree angle? Or do I have to remove the motor or intake & head to do this. I originally rethreaded the holes to metric, it worked fine, but after removing the bolts, because I had to put in heli coils in the exhaust pipe end of the exhaust manifold (by the heat valve) the are now weak again in the center 2 bolts.
Has anyone here done this in the motor in the car and can advise?

Thanks
Jack
1961 Cadillac

Jack,

If I may suggest, when I use the heli-coil for quick repairs I used thread locker blue or red depending on the application and torque. I try to keep the thread locker just on the outside making sure the inside is clean.

I’ve heard and also checked for heavy duty repairs the best option would be time serts more $$$ but permanent.

Good luck..!