Anyone here weld sparkplug thread repairs?

[cardiffrob]

I've acquired another 1950s alloy sidevalve head (Real sidevalve, not an ALTA OHV conversion) but it appears one plug thread has been tapped off at an angle and the seat knackered up a bit. Does anyone here weld and recut threads or can anyone recommend someone to do it? A bit out of my league in terms of the skills required and I'd rather not make things worse. Basically, I'm chicken!

I'm fairly certain that the helicoil in it can be removed but the hole is now so oval that it either needs welding or some sort of oversized alloy plug let in and then a new hole cut.

Thanks

Rob

 

[Cobbler]

Hi Rob, I've never used them, but some engine rebuilders use a threaded bush insert to repair plug threads. I don't know what they are called or whether they are big enough to replace a Helicoil. I'm sure someone on here will know what they are. If no one comes forward, I have to go down to the local engine guy in the next few days & I will ask as I know he uses them.

 

[Seadog]

They're called Time Serts and are made by Wurth. There are a couple of similar ones on the market from other manufacturers I believe.

 

[mike os]

They're called Time Serts and are made by Wurth. There are a couple of similar ones on the market from other manufacturers I believe.

Sit down when you get a price

 

[Cobbler]

Sit down when you get a price

I agree, I looked at the price of the kits on line, but if it recovers a a damaged head, it may be worth it.

 

[Seadog]

I'd look for an engine rebuilder. Even if they charged £50 for the repair it'd be worth it I would imagine. There are 3 Google sponsored hits for your area Rob.

 

[doubleboost]

I have welded alloy sump plug holes up then rethreaded
As long as the alloy is decent it should not be a problem

 

[wristpin]

The Wurth Time Sert inserts are unique in incorporating an mechanical expanding locking function whereas the cheaper copies require the use of a thread locking compound. Worth the extra imo !

 

[dannyp]

anything on a cyl head really needs mecanical locking, espectaly if it's pokeing through into the chamber. i would have thought a spark lug is going to be getting towards the temps that would ease most if not all flavors of locktite.

ive not welded loads of heads but done a few. have and AC tig here with enough power if your stuck

 

[awemawson]

I'd be tempted to machine the hole oversize, and tap it with a tapered thread like BSPT then make a suitable insert, screw it in dead tight, machine off the surplus, and insert a roll pin in a blind drilling at the interface of the head and insert to stop it unscrewing.

Welding is going to distort the head, and it may not be a nice alloy to weld anyway.

 

[mike os]

I agree, I looked at the price of the kits on line, but if it recovers a a damaged head, it may be worth it.

Definitely. ...

 

[Burdekin]

I used Coventry Boring and Metaling. Give them a call, very experienced guys.

 

[cardiffrob]

Thanks, everyone.

I like the idea, Awemason. I guess it could even be lightly TIG'd at the top to prevent unscrewing. I also wondered about going to 18mm plugs. Only a 6:1 comp ratio so not exactly a high performer.

Burdekin. Ta. I'll call them today.

 

[cardiffrob]

Same as the one at the bottom here. I did also wonder if it was possible to braze the iron head to match the shape of the alloy one.



Awaiting a reply from Coventry Boring Co.

 

[clarkey31]

Its a time sert kit i have got in work Rob so you can borrow that and see if it will work if all else fails
Gavin

 

[cardiffrob]

Thanks, Gav. I'll have a look when I next see you.

I've also just had an E-mail back from CBM (Coventry Boring) and they simply say they can't help without giving any other details.

DannyP. Thanks for the offer. I may need your help or advice if other avenues don't work out. Ta!

 

[EddyP]

I used Coventry Boring and Metaling. Give them a call, very experienced guys.

They'll be the same cowboys that completely ******** a Volvo T5 block for me. Gave them the pistons and the details of the clearance and then they supposedly knocked the machine when they walked past and considerably overbored it.
Was not a happy bunny, especially as I'd spent a LONG time prepping the block, cleaning it up, painting it etc...
Then had to find another block which meant buying new mains and all sorts. All in I think they cost me about £300.

Certainly won't be using them ever again.

 

[doubleboost]

If you are stuck I would be happy to sort it out for you
Ether a bush or weld & re tap

 

[premmington]

Extra vote here for: Timesert kit.

I have used these on all sorts of vehicles and they work!

 

[cardiffrob]

Thanks, Doubleboost. I'll have a look at these Timeserts that Clarkey has got and if it doesn't work out I'll get in touch.