Re: Heli-coil on cylinder head
Dan, Time-Serts are very nice and quite frankly are a better repair than a Heli-Coil, however, they are quite expensive. You might be able to find a good deal on a 14MM Time-Sert kit on eBay if you look for a while.
For a less expensive repair which will probably work fine on your old Merc, the Heli-Coil kit should do the trick.
Can't post a link to any website with the product 'cause this site don't allow. However, if you just Google up "Helicoil 5334-14" you'll get plenty of hits. Or go to eBay and search for same.
Note that Perma-Coil 2200-14 is the equivalent of the Heli-Coil kit and one of those is listed on eBay right now for $9.95 Buy it Now +$4.95 shipping. Probably won't find anything much cheaper than that!
The nice thing about either the Time-Sert or Heli-Coil kits is that they use a stepped tap. The tap has a normal spark-plug-thread-sized part which helps the tap self-start into the larger, stepped portion of the tap which actually cuts the right size threads for the new insert.
Be sure to use some heavy grease (wheel bearing or similar) on the tap, this'll catch most of the alum shavings as you're cutting the new threads.
It'd also help to position the motor so that the spark plug holes point downwards as you're tapping the hole. A bit awkward but will keep shavings from falling into the piston.
When you're done threading, pull the motor over with the recoil with the plug holes still pointing down. This'll shoot out any stray chunks.
Before you install the new insert, clean the hole and insert with degreaser and use some red Loctite or equivalent thread-locker. This'll prevent the insert from backing out.
Note that your motor probably uses a "J"-series Champion spark plug which has a 3/8" reach. Be sure you use an insert similarly sized.
HTH..........ed
p.s. your motor doesn't have a separate cylinder head so that option is certainly out! And definitely don't run until fixed, if it blew out once, it'll do it again.
