Aluminum head, still on vehicle. I know summit sells a tool to "repair" stripped spark plug holes, but I don't understand how that would work- because if a hole is stripped, the metal is gone, how can you re-thread it and fit the same size plug in there? What else can be done that won't require pulling the head? Would a heli-coil work or would I have to drill the hole bigger- meaning I'd get filings in the cylinder? If I end up pulling the head, then what is the best fix? Is aluminum easier to work with than iron? Thanks in advance

 

A heli coil will work , but you are going to have to drill the hole for the specified tap and you will get metal shavings into the bore but a shopvac should be able to take care of that. The best thing to do would be to pul the head and do it with acces to both sides of it.

 

How does this sound? Too good to be true? From the way it looks they say you dont need to pull the head.

SUM-900190
$25.95
Vendor: Summit Racing Equipment
Product Line: Summit Spark Plug Thread Repair Kits
Material: Steel
Finish: Black
The cure for stripped spark plug holes
M14-1.25 thread, with 3/8 in. short, 1/2 in. normal, and 3/4 in. long inserts, thread repair kit
Don't let a stripped spark plug hole get in your way. Keep our spark plug repair kit in your shop or at the track instead. Designed to work with aluminum and cast iron heads, the kit will permanently repair stripped threads easily and without drilling. Each kit includes an expanding tool, piloted tap, and short, normal, and long insert. Compatible with taper seat or gasket type spark plugs.
Sold as a kit.

 

sounds ok but i think i'd go with heli coils. you wouldn't have to pull the head to use a heli coil, but it'd be lot cleaner job if you did. if i pulled the head i'd do all the holes and not just one. is this a good time to mention antiseize and a torque wrench?

 

Definitely. Especially on an Alum. head.

You also definitely want to go with the heli coli if you want the repair to last. I've never had a problem with anything I've used a heli coil on; it will be stronger than new!

 

If you have a minute take a look at the picture summit gives with that part number. Isn't that basically a heli coil?
I am so paraniod about stripped threads, I'd never strip anything. I bought it that way, I swear! lol.

 

It looks like a heli coil, but those inserts almost look like they are solid. Heli coils are not. Hard to tell for sure from that picture, even the large pic. It does, however, look like something that would last.

 

Thanks. I just wrote summit an email asking about the kit, we'll see in 72 hours or less if this is safe to use without taking the head off. I'd probably still rig up a shop vac to fit in the hole after I was done just to be a little neater though.

 

what about that goup they sell at the autoparts store comes in a tube like RTV sealant says to fix stripped bolts and stuff. But I used a Heli Coil in the head of my 70 Camaro for my alternator never had a problem with it.

 

I've heard if you coat the drill bit with grease, the grease catches the metal filings, and keeps 'em from falling into the engine-- but I never tried it. Anyone try it, or hear of this done before?

 

That's actually a really good idea. The kit I'm looking at says it doesnt require drilling, but it's got to cut the metal somehow, and grease will definetly pick up most of the mess. Still waiting for summit to get back to me, thanks for all the ideas so far.

 

That Summit item is a standard industrial thread replacement shell, with an aftermarket automotive price tag.

You can get the same thing in steel, 300-stainless, 400-stainless, phosphor bronze, plastic, titanium, etc., from McMaster, Fastenal, Headco, and probably a thousand other industrial suppliers.



I'd insert all the threads while you were at it. That USED to be S.O.P. with aluminum castings in a performance application, but that was way back before the silicon aluminum casting process was perfected (incidentally, by Chevrolet as a result of the Vega).