Is it worth it to try to repair the threads on a 231 spark plug hole with a helicoil? Anybody done it with success?

simce they were designed initially for automobiles i would have to say yes they will. I used one in a honda 750 once.

Smile! people will wonder what you're up to!!

simce they were designed initially for automobiles i would have to say yes they will. I used one in a honda 750 once.

Yep, there used in Aviation on every engine Lycoming makes... they come from the factory with Heli-Coil inserts, lol

Later,
Jake

Jake Wiggins: AMA 856496

Except that the helicoil kit may cost more than a new cylinder!

Paul.

Helicoil kit cost more than cylinder

Yep, I checked into it, and the helicoil kit costs more than the $38 cylinder head. That makes it a no-brainer.

Keensert is the best, but a little pricy.
KD makes a threaded sleeve that will work if installed carefully.
You can find them at your local auto parts store.Fairly inexpensive.

Can you get a bigger spark plug?

And just tap and drill the hole out to the larger size? Kidding but who knows?

-=>Raja.

1005-G G26 3D Max, 3329 flts
Spectra-G G270 3D Max, 2194 flts
Whiplash-G G270 3D Max, 270 flts

Again, cost issue

If you have a machinist friend (or a buddy at the tool-shop where you work), I think it's simple enough to fit in a larger spark plug. But if you have to pay for the work, it's likely to be more expensive than $38...

What I like with the Heli-coil solution is that you know you're good to go for the next few years. I hate threading plugs into aluminium.

Gigi

My heli spending has gone way down since I got a Honda 919 :-)

Boys! Boys! Boys! for all the brains you guys demonstrate in building these sophisticated pieces of machinery, you forget one simple fact: Anytime you use aluminium againgst aluminium threads, its called anti-sieze, it keeps the threads from gaulding, the reason Heli coils work is because they are steele not aluminium threads.

Respectfully, Chuck Maddox

I can't say I've ever seen a spark plug with aluminum threads. Every Spark plug I have seen has steel threads. So it is not an issue of AL on AL galling. It is more a matter of using to big of a wrench and or too much muscle. You don't need to crank on a spark plug like it was a head-bolt on the Chevy 350 in your old pickumup truck.
As often as we pull out plugs to check for color I don't know if anti seize is necessary, but on the other hand it won't hurt.

Helicoils work because the new tapped hole is bigger than the old hole and therefor spreads the load out over a larger area. IE the same torque will have less PSI on the thread form because there are more square inches to spread the load out.

A small engine repair place might be able to do a Helicoil for a reasonable cost.

Jeff Borowski
RAMS Club President
www.ramsrcclub.com

Just Engines

Contact http://www.justengines.co.uk/ they'll sort you out.

I smile, cause I've no idea what's going on.

Whenever you're threading something into aluminum that you intend to remove and replace often, such as the sparkplugs in our engines, antisieze compound is priceless. It's one of those "ounce of prevention" things.

I also have to agree with Jeff that alot of guy's just use too much torque when tightening plugs, as well as, other hardware. We've all seen the guy with the Raptor or other plastic framed heli with half of the screw holes stripped. You can always tell by the number of big slotted panhead screws in the heli.

I've helicoiled a couple plugs on my Corvair engine (aluminum heads) that is used to power my Pietenpol Aircamper. No problems at all. It's actually a preferred modification since plugs get pulled and cleaned every 100 hours.