Spark Plug Thread Repair
Thread Starter
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HDF Community Team
Joined: Dec 2005
Posts: 5,403
Likes: 2,605
From: NC USA
Thanks for the input everyone. I do sincerely appreciate it! I may be over thinking this operation all together ....
Yeah, weld up and re-drill/tap would be the ultimate..
The "pro" heli-coil kit is expensive as is the time-sert which I kinda like the looks of, but I'm stingy
I have used a lot of heli-coils over the years for other things with total success.
There's lots of choices out there, many specific for ford engines. I'm a little gun shy of the ones that include a staking tool, though those inserts may work well as anything. I do like the idea of a 2 step reamer/threader. Again, I've never done one so have nothing but y'all's experiences to go by.
So, those that have used heli-coil kits, were those the coil type inserts like normal, (and look like you have to "stack" them to length?) or did you use the "sav-a-thread" that is marketed under heli-coil with one piece barrel inserts? And YD, the el cheapo set you used, was it similar to the time-sert style but with a different installer?
Yeah, weld up and re-drill/tap would be the ultimate..
The "pro" heli-coil kit is expensive as is the time-sert which I kinda like the looks of, but I'm stingy
I have used a lot of heli-coils over the years for other things with total success.There's lots of choices out there, many specific for ford engines. I'm a little gun shy of the ones that include a staking tool, though those inserts may work well as anything. I do like the idea of a 2 step reamer/threader. Again, I've never done one so have nothing but y'all's experiences to go by.
So, those that have used heli-coil kits, were those the coil type inserts like normal, (and look like you have to "stack" them to length?) or did you use the "sav-a-thread" that is marketed under heli-coil with one piece barrel inserts? And YD, the el cheapo set you used, was it similar to the time-sert style but with a different installer?
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,079
Likes: 2,151
From: Ohio
Here is what I'm thinking, Evo heads are known to crack from the spark plug hole into a valve seat, have one of those heads holding paper down. If your drilling out material in the spark plug hole area it is weakening the area that is already prone to cracking, just clean and inspect the area real well if your going forward with a repair coil system. On a side note Screamin Eagle heads went to the smaller spark plug to put more material in the area.
Thread Starter
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HDF Community Team
Joined: Dec 2005
Posts: 5,403
Likes: 2,605
From: NC USA
Here is what I'm thinking, Evo heads are known to crack from the spark plug hole into a valve seat, have one of those heads holding paper down. If your drilling out material in the spark plug hole area it is weakening the area that is already prone to cracking, just clean and inspect the area real well if your going forward with a repair coil system. On a side note Screamin Eagle heads went to the smaller spark plug to put more material in the area.
Road Warrior
Joined: Dec 2007
Posts: 1,286
Likes: 64
From: SoCal
t150vej,
1997bagger's post got me thinking that if/when you have your spark plug hole welded and re-drilled you could have it filled enough to re-drill it for the smaller Screamin' Eagle plug which I imagine is available in a heat range you need.
If you cannot afford the weld repair right now I'm pretty sure you can fix the threads with an insert.
I have heard that Helicoils don't work well in spark plug holes but I haven't had to repair one yet.
If you intend to do this with the head on the engine I suppose you could put air pressure to that cylinder from the exhaust port fairly easily to blow the thread cutting chips out at the spark plug hole. I figure you would get at least most of them out.
I hope you post the results of whatever you decide to do.
1997bagger's post got me thinking that if/when you have your spark plug hole welded and re-drilled you could have it filled enough to re-drill it for the smaller Screamin' Eagle plug which I imagine is available in a heat range you need.
If you cannot afford the weld repair right now I'm pretty sure you can fix the threads with an insert.
I have heard that Helicoils don't work well in spark plug holes but I haven't had to repair one yet.
If you intend to do this with the head on the engine I suppose you could put air pressure to that cylinder from the exhaust port fairly easily to blow the thread cutting chips out at the spark plug hole. I figure you would get at least most of them out.
I hope you post the results of whatever you decide to do.
Last edited by megawatt; Dec 15, 2019 at 07:19 PM.
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,590
Likes: 3,361
From: Cental, MI
Thanks for the input everyone. I do sincerely appreciate it! I may be over thinking this operation all together ....
Yeah, weld up and re-drill/tap would be the ultimate..
The "pro" heli-coil kit is expensive as is the time-sert which I kinda like the looks of, but I'm stingy I have used a lot of heli-coils over the years for other things with total success.
There's lots of choices out there, many specific for ford engines. I'm a little gun shy of the ones that include a staking tool, though those inserts may work well as anything. I do like the idea of a 2 step reamer/threader. Again, I've never done one so have nothing but y'all's experiences to go by.
So, those that have used heli-coil kits, were those the coil type inserts like normal, (and look like you have to "stack" them to length?) or did you use the "sav-a-thread" that is marketed under heli-coil with one piece barrel inserts? And YD, the el cheapo set you used, was it similar to the time-sert style but with a different installer?
Yeah, weld up and re-drill/tap would be the ultimate..
The "pro" heli-coil kit is expensive as is the time-sert which I kinda like the looks of, but I'm stingy
I have used a lot of heli-coils over the years for other things with total success.There's lots of choices out there, many specific for ford engines. I'm a little gun shy of the ones that include a staking tool, though those inserts may work well as anything. I do like the idea of a 2 step reamer/threader. Again, I've never done one so have nothing but y'all's experiences to go by.
So, those that have used heli-coil kits, were those the coil type inserts like normal, (and look like you have to "stack" them to length?) or did you use the "sav-a-thread" that is marketed under heli-coil with one piece barrel inserts? And YD, the el cheapo set you used, was it similar to the time-sert style but with a different installer?
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,198
Likes: 3,087
From: NW AR
If it was mine, and I had the head sitting in my hand(s), I would bring it to an automotive machine shop and have them weld it up, drill and tap it. If it was still on the bike, I would put the piston at BDC, fill the cylinder with shaving cream, put in a helicoil or timecert, (probably helicoil because they are more readily available), crank the motor to blow out the shaving cream/chips and ride on.
Met a guy at Sturgis, maybe '87 or so. He had a shovel and was running the old style giant spark plugs, like tractors use. He had the regular plug blow out the head on him. Just drilled and tapped it for the large plugs and kept riding. He had a lot of miles on it too. Especially by shovelhead standards.
Met a guy at Sturgis, maybe '87 or so. He had a shovel and was running the old style giant spark plugs, like tractors use. He had the regular plug blow out the head on him. Just drilled and tapped it for the large plugs and kept riding. He had a lot of miles on it too. Especially by shovelhead standards.
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Grand HDF Member
Joined: Apr 2007
Posts: 3,725
Likes: 3,070
From: Brighton, MI
"And YD, the el cheapo set you used, was it similar to the time-sert style but with a different installer?"
The set I picked up about 20 years is made by "Perma-Plug, from a farm and fleet store on sale for about 15 bucks.
https://www.walmart.com/ip/Perma-Plu...-Kit/199947031
It is the stake in place style, so might be a little risky with the evo head. Never had a problem with it backing out of the triumph head, but always wondered if it would I used red loctite when installing (along with staking it in per the directions) but with the heat, the loctite probably didn't help any in regards to holding it in place.
Do you have any planned down time with the bike? If you need the bike up and running then helicoil until you have some down time to get it welded up. There is a helicoil kit on amazon for 25 bucks. YD
The set I picked up about 20 years is made by "Perma-Plug, from a farm and fleet store on sale for about 15 bucks.
https://www.walmart.com/ip/Perma-Plu...-Kit/199947031
It is the stake in place style, so might be a little risky with the evo head. Never had a problem with it backing out of the triumph head, but always wondered if it would I used red loctite when installing (along with staking it in per the directions) but with the heat, the loctite probably didn't help any in regards to holding it in place.
Do you have any planned down time with the bike? If you need the bike up and running then helicoil until you have some down time to get it welded up. There is a helicoil kit on amazon for 25 bucks. YD
Tourer
Joined: Sep 2017
Posts: 280
Likes: 96
From: DFW Texas
Don't know about the Timesert sparkplug repair, but I did put in an oil pan repair on my wife's Honda (cast alum pan) and can say nothing but good things. Now the pan has a steel threaded hole and will never come out. I might even feel comfortable that I could take it to a Quik Oil type place and they wouldn't strip it out. Expensive, yes, but good, yes!