Helicoil

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Coyote Jack

Coyote Jack

Member #55, I'm old
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I have the engine out to check the crank and I am going to address a few other small problems while I am at it. One is I have 3 exhaust bolt holes that need to be helicoiled. They still have threads way in but out near the header flange somebody stripped the threads. I want to have proper header bolts in all the holes so enter the helicoils. My question is, are there any pitfalls that I should watch for when drilling the holes out? ie: adjoining passages to look out for

This is a set of "X" heads that have a lot of porting done to them.

Jack
 
Make sure that the drill bit is square to the hole both sideways and up and down. I use them all the time on my vintage motorcycles.They work well and are strong but they have to be straight.
 
Best to pull the heads and drill them out on a drill press.
 
Jack, "You can do it". I helicoiled 3 of the holes on the exhaust sides of my heads, 2 on one head & 1 on the other. I used my drill press vise & some shims to make sure the face was level, plumb & square to the collet. I drilled them & slowed the press down to its lowest speed to tap the holes. I made sure to use green LOCTITE on the coils to make sure the stay. If I can do it, you can. LOL
 
I've used Helicoils but prefer Keen inserts better. No wire to break off, coil to come unthreaded or bind up on install.
 
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Something to consider.....The end faster holes are "wet", in other words, they go into the coolant system. I'm not sure if they may require extra attention to seal from seeping if they are heli-coiled.
 
two things. 1- use the help coil drill bit. 2- make sure you drill straight / tap straight. It is easy . you can def do it. Oh. yeah. patience. take your time.
 
All great advice. So I take it I won't have any problems with the drill going in a place it shouldn't as long as I do my end correctly.

Jack
 
Locomotion said:
Something to consider.....The end faster holes are "wet", in other words, they go into the coolant system. I'm not sure if they may require extra attention to seal from seeping if they are heli-coiled.
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I have already been thinking about that. Must get everything sealed up real good.

Jack
 
I would also make sure you don't drill too deep, I would think there is water behind the blind holes. if the Helicoil is too long after drilling and tapping and installing, you can trim off the excess with a carbide wheel. The open holes on the ends of the heads, I would stop the tap short, so the Helicoil had a positive stop. Will keep it from threading in
 
Figure out the depth of the hole put tape on your drill bit at that point then you fer sure won’t go to far .
 
A Body 440 WHY NOT said:
two things. 1- use the help coil drill bit. 2- make sure you drill straight / tap straight. It is easy . you can def do it. Oh. yeah. patience. take your time.
Click to expand...
Agree- I accidentally used the wrong tap to clean the head bolt holes on a sbc , use the supplied drill bit
I drilled the holes without a template and it turned out beautifully
 
There is a block to keep things straight and perpendicular. If you use the block and are careful it will be good as new.
 
Heli-coils should be stainless steel, but ant-seize is always a good idea, especially stainless steel to stainless steel.
 
One issue you may run into. The head exhaust ports have been heat cycled for many years which hardens the cast iron. Use a quality drill bit.
 
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