Spark Plug Thread Repair

adrake – 7/11/06
Anyone used a helicoil or spark plug insert to repair a damages plug hole? I've got a block that could use a something as it's in decent shape other than this.  Any ideas? I've already tried a chaser and not enough thread left to be of help. I'm thinking this thing needs something pretty small.  Anyone know of a kit that'll do the trick?
kethc77 – 7/11/06
Yes, I've used a thread insert and it worked fine, but block has to be off engine. I got the kit from an auto supply. The kits have a few inserts, a tool that follows the old thread and cuts/reams it bigger, then cuts the new thread for the insert, then you put insert in and ready for the plug.
butch – 7/12/06
U.S. spark plugs have been metric sized for a long time, why?  I don't know.  Most everybody except Ford used 14 MM for years.  Your Crosley uses 14 MM X 3/8" reach.
berard_m – 7/122/06
NAPA has a kit we use in times of need. You can get 3 eights, half inch, or 3 quarter reach inserts. (also 18 mm I've used on my hit and miss engines) Use lock tite or similar stuff. There is usually a tube of stuff that comes with the reamer and bushings, but I've had them back out with the plugs years later. I like to clean all the fresh hole and the bushing with Brake Clean or carbon tech to get rid of the grease on the surfaces prior to the final instulation. Liberal use of chassis grease on the tap/reamer will help to keep the filings out of the cylinder. Some will no doubt get in. Cautious tapping and frequent removal and cleaning of the scraps will also help. I always advise the customer that there is a risk of damage from some metal getting in the cylinder, but out of 50 or so we have done over the last 45 years, we've yet to have a problem requiring the removal or the head. Gun her good when you first crank her to blow out the leftover giblets.
apdrake – 7/12/06
You know, this is one of those "Duh!" things I shoulda known. Even more so when I took a spark plug to NAPA and got a kit. It worked perfectly. Got a little "coffee grounds" into the cylinder, but used a Shop Vac narrow nozzle to get the stuff out.
bugger5913 – 7/18/06
Years ago I used a helicoil on a 1959 Renault that had an aluminum head, worked fine. just use plenty of loctite on the coil to insure it stays in the block.  Every time I would change plugs the helicoil would come out with the spark plug.....