Helicoil Question

[sludgeguy68]

Found a stripped thread for cylinder head screw - bought a 5/16 Helicoil kit and started tapping. I noticed the Helicoil threads are kind of short in comparison to the length of the threads on the bolt.

Do I need longer Helicoils? The lower threads still seem to be intact; not sure if I can just put the short Helicoil in and it will line up. This is the first time I've done this...

1973 25hp rude
Thanks!

 

[Daviet]

Re: Helicoil Question

If your luck is anything like mine the threads will not line up. I have always drilled out the threads and installed the longest heli-coil I could get, has always worked for me.

 

[bob johnson]

Re: Helicoil Question

Found a stripped thread for cylinder head screw - bought a 5/16 Helicoil kit and started tapping. I noticed the Helicoil threads are kind of short in comparison to the length of the threads on the bolt.

Do I need longer Helicoils? The lower threads still seem to be intact; not sure if I can just put the short Helicoil in and it will line up. This is the first time I've done this...

1973 25hp rude
Thanks!

they will not line up...the start of your helicoil tap had no knowledge or correlation to the original thread!!!!!!!!!!!11...

if it does, it would be shear luck....

you can use two helicoils...back to back... they will line up with each other in the deeper tapped helicoil thread.....IF you cant find a long one



JUST make sure they are shorter in total length than the depth of the Helicouil tap, tapped hole!!!!

and make sure you drill out the old thread all the way!!!..BUT..DONT push the original hole any deeper!!!!!!!!!!!!!!!!!!!!!

good luck


bob

 

[sludgeguy68]

Re: Helicoil Question

Yup, couldn't find a longer Helicoil, tool shop suggested to break one tang and put the coils end-to-end. Will drill and see if it works... crossing fingers!

Thanks for the help!

 

[bob johnson]

Re: Helicoil Question

you should have to break the tangs til you are happy they both fit all the way into the hole..

if you screw the first one in and break the tang, then go to screw the second one in and it hits the first, BEFORE it is past flush, then you are in a little trouble...

leave the tang( it is possible to back out with the tang still in place...kinda maybe ish ha ha) on the first one after you screw it in to where you think is deep enough

then when the second goes in and touches the first one and is below the surface of the block...then you can break the second helicoils tang and then go ahead and break the first helicoils tang...

whew...that sounds confusing ha ha

good luck

bob

 

[sludgeguy68]

Re: Helicoil Question

Yup - I realized I couldn't put the top coil in without a tang, for some reason I thought it would just follow the first one

I pretty much did exactly what you said, kinda guesstimated how far down the first one should be, then put the second in, then broke both tangs. Looked like there was a small gap between the two coils, but I screwed the insert tool in and I think they lined up.

The bolt seemed to go in and torqued fine. I feel like the top coil might come out when that bolt comes out again, but hopefully everything will stay in place.

Thanks for the help, much appreciated!

 

[boobie]

Re: Helicoil Question

If it was me I'd just put one Heli Coil in it and be done. With two Heli Coils in it you still have to worry the threads will still line up. When done the threads in the block will be stronger than the orginial threads were.

 

[bob johnson]

Re: Helicoil Question

Yup - I realized I couldn't put the top coil in without a tang, for some reason I thought it would just follow the first one

I pretty much did exactly what you said, kinda guesstimated how far down the first one should be, then put the second in, then broke both tangs. Looked like there was a small gap between the two coils, but I screwed the insert tool in and I think they lined up.

The bolt seemed to go in and torqued fine. I feel like the top coil might come out when that bolt comes out again, but hopefully everything will stay in place.

Thanks for the help, much appreciated!

there is no worry about the thread slining up because you used two inserts..they are on the same path!!!! they cannot diverge ha ha


you are fine no matter how big a gap you have between them....as long as the second one is below flush you are fine...

two is way better than one....you spread the torque load out.... and cab basically torque twice as much before you pull the threads out...

not that you would....the helicoil is really strong once the bolt is inserted...

I wouldnt worry about either backing out...and if it does..you can grab the edge with a wire and pull it out....it will probably come out looking like a bent wire..and not a thread insert any more....

the wire will just take the shortest path.....done it many times


good luck

bob