Heli coils in heads - opinions

[erik70rt]

I recently found a set of heads for my 340 that fit my needs.  I know some of the exhaust manifold mounts have been heli-coiled.  I am leary of them in that will they cause fitment issues/leaks. 

Thoughts on heli-coils in heads? 

[TelisSE440]

I do have helicoil in my driver side 906 head. The rear exhaust stud which has access in coolant too. I didnt have any leaks but i used aluminum multi layer gasket along with copper gasket sealer. The helicoil was also screwed a little crooked, so i had  to drill the headers a little. Anyway, if you can avoid it don't buy them IMHO...

[Shane Kelley]

I would be worried about seepage on the end exhaust bolts where the studs usually are. Other than that I have no issues with heli-coils. They are stronger than the original material most times.

[oldmoparbuff]

I have had good success with helicoils.
I have a 360 in my truck that I had to helicoil exhaust manifold bolt.
Red loctite on helicoil.
Thread sealant on stud.

Edit to add, if you use red loctite on helicoil let it set overnight before you install the stud or bolt.

Manufacturer I used to work for, helicoils where an Engineering approve repair.

A better repair we did in cast iron was to drill, tap and chamfer to a bigger bolt.
Weld the bolt to the cast iron.
Mill surface and redrill and tap.

Required a skilled welder, preheating cast iron and a mill.
Hard to do in a garage.

[gzig5]

Done correctly, Heli-Coils will work fine and you'll never know they were there in normal operation.  The only time you could have a problem is if you have to remove the exhaust after some years, the coils may come out with the bolt.  If the price is right I'd go with them.

[YellowThumper]

Definately would stress the Helicoil point to seller for cost.
That said I would not shy away from purchases with them. If you cannot see them in person. I would request many pictures of the repairs. Direct face shots of them to show they are in correct location. Also with long bolts screwed into then and several side shots to confirm they are in straight. You dont want to see a crooked long bolt standing up.
Good luck.

[Chryco Psycho]

Coolant can seep up the outside of the helicoil even if you seal the bolt the to insert . timeserts are a better option

[JS29]

@Chryco Psycho  timeserts? Let's hear more, It sounds like a better alternative. 

[YellowThumper]

For visual, a Helicoil is much like a spring. Where the coils are not directly connected to each.
Timesert is a solid piece that is threaded inside and outside.
Thus more capable of sealing fluids.
FWIW I have repaired several with the Helicoil and they have all sealed properly.
Proper repair is key to success. If these are already Helicoil then you are tied to their repair. They need to instill confidence in the repair quality.

[Cudakiller70]

@Chryco Psycho  timeserts? Let's hear more, It sounds like a better alternative. 

Just looking at these yesterday

[73440]

Watched a video today using key lock insert in an aluminum head.
https://www.youtube.com/watch?v=en5s0x3583s

How does the key lock insert compare in holding power with the timesert ?

https://www.mcmaster.com/threaded-inserts