Destroyed head bolt threads HELP

[DylanS]

i Have a set of gp800 cylinders that were over bored and resleeved, and ported for a 5mm stroke
Basically I can’t get new cylinders

Every single head bolt is completely stripped out, and the guy who helicoiled it before absolutely butchered them to the point where I can’t even get them torqued.

I’m desperate, does anyone have any idea on how to even begin to fix an issue like this?
I can’t use inserts as the threads are crooked

Was considering having someone stick weld aluminum into the threads and having a machine shop drill and tap it out, but I’m scared it’ll warp the material around it

Anyone have any idea if there’s enough material to have it drilled and tapped to a 10x1.25?
Any suggestions would be a godsend at this point, thanks

 

[Jr.]

When head bolts strip, many people use Helicoils as the first form of repair.
The next form is typically a timecert or Keycert repair. Depending on the degree of oversize required.
Your issue is not unusual. But it will not be cheap! You will need to have a machine shop preform the work.
Typical repairs run in the range of $15-20. Per insert installed. If the previous repair was so poor that the holes are no longer square to the deck? And possibly lost location? Then you will need to bring your head with the cyls to the machine shop to help the machinist get the new inserts located correctly. Make sure the inserts are stainless.
Look for a local tool & die shop that will do small scale work.

Ski ya, Paul

 

[iQRTurbo]

Is there enough material to remove the helicoils drill and tap deeper and move to a longer bolt?

 

[cudaben]

I had a similar issue on a ported 760 cylinder.
I ended up having to weld to holes (tig) up and re drill and tap.

There are always ways to fix things, it just depends on your budget . It was cost effective for me to have the holes filled and retapped vs buying a new cylinder, boring it, and then porting it.

 

[vomitspot]

time sert is the way ! but like jr said not gonna be cheap

 

[TheBuzzard]

one of my cylinder holes that the head bolts to was helicoiled and it pulled out . the hole was so oversized that I couldnt just go to the next size.
there wasn't enough meat there for a time cert either. I ended up tapping the hole to 7/16 and making a step bolt.
7/16 on one end and I ground the other end down so I could thread it to 8mm or 5/16.
sure, I could have taken it to a machine shop and had it welded and rethreaded, but that wouldn't have had my ski back up and running in a few days after I blew it up and it would have cost a bunch of money.
its personally satisfying to hillbilly fix something and have it work.
any knucklehead can just fork out money, if they can afford it, and have something professionally fixed.
I takes a real mechanical genius to butcher fix it and make it work

 

[DylanS]

When head bolts strip, many people use Helicoils as the first form of repair.
The next form is typically a timecert or Keycert repair. Depending on the degree of oversize required.
Your issue is not unusual. But it will not be cheap! You will need to have a machine shop preform the work.
Typical repairs run in the range of $15-20. Per insert installed. If the previous repair was so poor that the holes are no longer square to the deck? And possibly lost location? Then you will need to bring your head with the cyls to the machine shop to help the machinist get the new inserts located correctly. Make sure the inserts are stainless.
Look for a local tool & die shop that will do small scale work.

Ski ya, Paul

Thanks Paul,
I was just unsure of there being enough material left for the machinist to even seat new inserts for the same size thread
I will ask my buddy tomorrow

Appreciate the fast reply!

 

[DylanS]

Is there enough material to remove the helicoils drill and tap deeper and move to a longer bolt?

I wasn’t sure if there was enoigh material to drill deeper and tap it, I’m going to rip the cylinders off today and try to see what I’m working with
Thanks man!

 

[DylanS]

I had a similar issue on a ported 760 cylinder.
I ended up having to weld to holes (tig) up and re drill and tap.

There are always ways to fix things, it just depends on your budget . It was cost effective for me to have the holes filled and retapped vs buying a new cylinder, boring it, and then porting it.

So you can have them tigwelded without melting/warping too much of the material?
That seems like what I may do for a permanent fix as the holes are awfully oblonged,
Thanks for the help man

 

[Req]

I was just looking at my container of Devcon liquid aluminum I am going to use for case porting and it says its machinable and tapable. @Jr. would probably know if its stout enough but I found it interesting.

Here is the datasheet
https://itwperformancepolymers.com/media/1013/aluminum-liquid-f-2_041418.pdf

 

[Jr.]

one of my cylinder holes that the head bolts to was helicoiled and it pulled out . the hole was so oversized that I couldnt just go to the next size.
there wasn't enough meat there for a time cert either. I ended up tapping the hole to 7/16 and making a step bolt.
7/16 on one end and I ground the other end down so I could thread it to 8mm or 5/16.
sure, I could have taken it to a machine shop and had it welded and rethreaded, but that wouldn't have had my ski back up and running in a few days after I blew it up and it would have cost a bunch of money.
its personally satisfying to hillbilly fix something and have it work.
any knucklehead can just fork out money, if they can afford it, and have something professionally fixed.
I takes a real mechanical genius to butcher fix it and make it work

There is a lot to be said about solid redneck engineering! The ability to think outside the box has taken me miles further than any school has ever taught me! Sometimes its the best route! It just scares me to suggest it sometimes when I don't know what I’m actually dealing with.........

I was just looking at my container of Devcon liquid aluminum I am going to use for case porting and it says its machinable and tapable. @Jr. would probably know if its stout enough but I found it interesting.

Here is the datasheet
https://itwperformancepolymers.com/media/1013/aluminum-liquid-f-2_041418.pdf

I like and use Devcon in multiple applications. I avoid using it in a known high torque application such as this?
It might get you thru an emergency fix? I don't know about a permanent one tho?

Ski ya, Paul

 

[Req]

@Jr. That would be my concern as well. I picked the stuff for case porting because it seems to flow well and doesn't shrink a lot and should avoid any air bubbles. I dont think I would trust it for high torque like you said.

I ended up with some extra, what other uses other than case porting and crossover fill have you found?

Off topic, sorry.

 

[iQRTurbo]

If you go the tig weld route in a blind hole such as a head bolt you will certainly not get good enough penetration and fill going in from the top. It will only burn in at best the top 3/8 of an inch. I have made many similar repairs on a host of other applications by filling with weld and had good luck repairing but I would recommend opening up the side of the cylinder to expose the length of the striped out hole and fill your way back out full depth.

That being said, only weld as a last resort if you cannot drill deeper and go to longer bolts or install time serts. Welding on the cylinder obviously produces heat that will anneal the hard casting and make it softer. Post a picture of your issue so we can make a more informative recommendation.

 

[DylanS]

work[/QUOTE]

If you go the tig weld route in a blind hole such as a head bolt you will certainly not get good enough penetration and fill going in from the top. It will only burn in at best the top 3/8 of an inch. I have made many similar repairs on a host of other applications by filling with weld and had good luck repairing but I would recommend opening up the side of the cylinder to expose the length of the striped out hole and fill your way back out full depth.

That being said, only weld as a last resort if you cannot drill deeper and go to longer bolts or install time serts. Welding on the cylinder obviously produces heat that will anneal the hard casting and make it softer. Post a picture of your issue so we can make a more informative recommendation.

i will get a picture up tonight
It’s just a bunch of 8x1.25 ID helicoils that are crooked enough to prevent the bolt from threading in and aren’t seated deep enough

I was worried that the heat would cause issues with wedling
I’m going to go to my buddies machine shop and see if he’s capable of squaring things up and maybe seating time serts if he has them
Hopefully I don’t have to open the sides of the cylinders up
I am unsure if it’s safe or if there would even be enoigh material to drill deeper than the depth of the existing head bolt threads
If there was extra material that would be an option but as of now I’m unsure
BIGcerts might be an option as the holes are drilled out to 21/64 and the big certs use a 26/64 with the same inner ID
But I’m unsure if there’s even enough wall left between that and the sleeve to drill it out any larger

 

[cudaben]

So you can have them tigwelded without melting/warping too much of the material?
That seems like what I may do for a permanent fix as the holes are awfully oblonged,
Thanks for the help man

A good welder will know how to do that properly.

Obviously the hole will have to be enlarged or cut open from the outside to fill it in all the way.

I had a few that were in need of repair. On the outside of the cylinder it was easy, I just ground down the material to expose a nice open area to weld.

On factory pipes with destroyed water screws i have had to really open the holes us, like to almost 1" wide tapering down and do multiple passes to build it back up to be able to drill and tap.

The heat generated can be confined to small area. It is also worth nothing for me in my 760 situation the ski started by itself and ran in my garage till it seized. This got so hot the paint blistered and the sleeves dropped. The metal was fatigued and it couldn't not hold the sleeves in their position. It took quite a while to figure out why I always had head gasket leaks... once it got up to operating temp the sleeve would drop. Finally the cylinder split on the very front showing me a stream of water pouring out of it. It was then that it all made sense and I knew that one was 2 far gone.

 

[DylanS]

A good welder will know how to do that properly.

Obviously the hole will have to be enlarged or cut open from the outside to fill it in all the way.

I had a few that were in need of repair. On the outside of the cylinder it was easy, I just ground down the material to expose a nice open area to weld.

On factory pipes with destroyed water screws i have had to really open the holes us, like to almost 1" wide tapering down and do multiple passes to build it back up to be able to drill and tap.

The heat generated can be confined to small area. It is also worth nothing for me in my 760 situation the ski started by itself and ran in my garage till it seized. This got so hot the paint blistered and the sleeves dropped. The metal was fatigued and it couldn't not hold the sleeves in their position. It took quite a while to figure out why I always had head gasket leaks... once it got up to operating temp the sleeve would drop. Finally the cylinder split on the very front showing me a stream of water pouring out of it. It was then that it all made sense and I knew that one was 2 far gone.

That’s extremely unlucky haha
So you don’t think the heat generated would be enough to warp the walls? I think I’d have to grind away the outside to weld as the holes can’t be enlarged anymore without hitting sleeve

 

[X2Kid]

Now that I'm older (and have some money) I just hand tricky stuff over to professionals and have them do the job properly. I then let the inherent nature of my gender (and age) let me forget the cost in next to no time and carry on my merry way. My bodging days are back in the past (along with the function of my knees, back and eyes).

And referring to cudaben's post, I have ALWAYS disconnected the earth cable on my battery when my 'ski's are unattended. I was always hearing horror stories of 'ski's starting of their own accord back in the early 90's. It seems it's still a trick played by modern 'ski's. The added benefit is that your battery will stay charged longer as there is no risk of a parasitic current draw.

 

[DylanS]

Now that I'm older (and have some money) I just hand tricky stuff over to professionals and have them do the job properly. I then let the inherent nature of my gender (and age) let me forget the cost in next to no time and carry on my merry way. My bodging days are back in the past (along with the function of my knees, back and eyes).

And referring to cudaben's post, I have ALWAYS disconnected the earth cable on my battery when my 'ski's are unattended. I was always hearing horror stories of 'ski's starting of their own accord back in the early 90's. It seems it's still a trick played by modern 'ski's. The added benefit is that your battery will stay charged longer as there is no risk of a parasitic current draw.

Yeah haha im just going to have a machinist take a look at this point
Yeah that’s always a good idea
I have a switched total loss so the worst that could happen is a destroyed starter lol
If it was easier i would disconnect my ground, maybe I’d better move my battery tray

 

[Zero Client]

Are you using girdled heads for the GP800 cyls? Not sure if thats even possible... but if you are using girdled heads then you may not need to use the factory head bolts. Maybe this isn't the greatest of options or a valid suggestion but its worth doing a little research. I for one always use both - head bolts and the head girdled bolts in a 701, but somewhere I've seen folks forgo the head bolts and just run with girdled bolts alone.

 

[DylanS]

Are you using girdled heads for the GP800 cyls? Not sure if thats even possible... but if you are using girdled heads then you may not need to use the factory head bolts. Maybe this isn't the greatest of options or a valid suggestion but its worth doing a little research. I for one always use both - head bolts and the head girdled bolts in a 701, but somewhere I've seen folks forgo the head bolts and just run with girdled bolts alone.

I am not running a girdle kit, although I probably should

My compression should be relatively high and I’m running a copper head gasket so I also had my doubts with sealing in compression using only four girdle bolts. Will most likely look into getting it studded for them anyways though as I have heads to accommodate them