SING F LTD14MM Spark Plug Repair 4 Inserts Thread Reamer Tap

love it

The spark plug thread tap was very difficult to thread. This was for a OHV Briggs & Stratton with a 5/8" long thread spark plug and spark plug threaded bore. I used a 1 1/2 foot long breaker bar 1/2" socket wrench with a 13/16 socket on the tap. With the lawnmower head off the lawn mower and fastened to a 2x6 about 6 feet long with deck screws with washers through the cylinder head holes and holes drilled in the 2x6 to fit the head alignment pegs I worked the breaker bar back and forth advancing it just a few points of a 12 point socket after 3 cycles with tapping oil. After over an 1 1/2 hours with breaks I got the tap through. I was sweating by the time I took a break.The tapping tool had cracked and razed the edge of the spark plug bore hole edge near the exhaust valve seat inside the cylinder head where the tap came through. That is probably not an issue, but I could have stopped using the tap 1/8" earlier and not had that happen.There were no instructions or any written information that came with the tool. Checking the Amazon description for this item had no instructions either. I found a YouTube Taryl Fixes All with a spark plug thread insert subject and he showed a similar thread insert kit recommended pre drilling with a 25/64s drill bit. That is 1/64s more than 3/8th drill bit. I didn't have 25/64 drill bit so I just continued on with my previous method.I tried the thread insert on the spark plug and it would not go on smoothly even after holding the spark plug in a vise and using curved jawed locking pliers gripping the thread insert to thread it up and down. I took some valve seat grinding compound and added that to the threads and worked the thread insert up and down the spark plug. That in short order got the threads working smoothly. I then washed and tooth brushed scrubbed off the grinding compound from both the spark plug and the thread insert.I used the spark plug to hold the thread insert to thread the insert into the hole. I used JB weld on the threads of the outside threads of the insert and the threads of the tapped threads of the head. The JB weld will lock the thread insert into the cylinder head and seal it. These thread inserts have been known to come out when removing the spark plug otherwise. JB weld needs to be monitored periodically as it cures because it flows and typically gets into places you don't want it. I watch and reposition the object using gravity to flow the JB weld towards where I'd like it over 6 - 12 hours. After 12 hours there is not much flow taking place with the JB weld. I let it cure 48 hours before putting on the lawnmower and starting the lawnmower.I spent about 3 1/2 hours on the project with the cylinder head already off the lawnmower when I started. If you've got a machine shop around your area I'd check with them about putting in a spark plug thread insert if you bring in the cylinder head. If it is $50 and they can do in a day I'd go for it. I think I've got a good permeant fix now, but a machine shop would do that also. The soft aluminum in lawnmower cylinder heads makes cross threading the threads almost a throw of the dice so it its best to put steel thread inserts into them. This thread insert unlike a heli-coil has a nice curved flange for the spark plug to seal against. This makes the spark plug ever so slightly have a little less depth into the combustion chamber, but it doesn't make any difference.If you buy this product I'd also purchase a 25/64s drill bit to pilot the tap hole. Even if you have one it would be best to start with a new drill bit. I like the solid thread insert better than the wire rap of a heli-coil. The thread insert after using valve lapping compound to work it back and forth on the spark plug seems like it smoother than a heli-coil. Hello-coils don't have to be cemented in.

Inserts are made of pot metal. Installed insert in chainsaw and it's fine so far. Just be aware

The tap was a waste of money