'72 250 Spark plug hole stripped
 

Was changing out plugs and wires and when I went to put in plug #5 (M130 inline) I noticed the hole is stripped and the plug won't torque down.

What are my options?

Thanks!

ryan

Timesert or Helicoil or new head.

Thanks.
Been checking options price wise online and the Timesert is considerably more expensive than the Helicoil - somewhere in the range of $250 to $30.

Is it worth it?

I have never used either before, although neither sounds terribly difficult and I have a pretty nice, straight shot at the hole.

I have never had much luck with Helicoil. Also seems like a one time fix, not something that would be removed regularly.

Timesert are great. I have had lots of success with them.

I'm assuming the head has to be removed? I guess the cut away material could be vacuumed out of the cylinder.

Timeserts are considered better. Should be able to thread with the head on the car. Use a strong vacuum at the thread site necked down with tubing to pinpoint the suction. Put grease on the threads of the tap to grab some of the swarf. You could open the exhaust valve on that cylinder and apply light air pressure with a shop vac exhaust or electric leaf blower to the tailpipe while tapping to blow chips out of the threads. Borescope the cylinder when done.

Good luck!!!

I’m really trying to avoid pulling the head…should be able to if I’m careful.

Shouldn't need to pull the head. Invest time into making certain that the tap is started on the correct angle. A long dowel fashioned into an adjacent spark plug hole would be a good reference. The longer the turning tool (extension) on the tap the better you'll be able to sense the angle. The side-to-side angle should be easy to see, it's the up-down that isn't so easy to get "spot on."

Good luck!!!

I am considering the Time-sert but there are numerous choices - do I need the extended version? Anyone recommend a kit for my application?

I'm not sure it's worth the cost as I've read a lot of "good" Helicoil stories...but I also own a 560SL with the same spark plug size, so it might be worth the investment.

TimeSert is preferred over Helicoil.

Just finished the repair today - no problems. After the suggestions made here I went with Time-Sert and am very pleased with the results.

Thanks!

nice news. -cth

Well done.

Drive on...congrats!!!