Stripped spark plug threads

Old 10-12-19, 10:46 PM
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Stripped spark plug threads

I have a 6.5 HP Briggs and Stratton engine on a Toro Recycler mower that has stripped spark plug threads. Do I just chase these threads with a tap and put in a new plug? Seems like I recall hearing about some thread insert repair kit.
Old 10-13-19, 03:10 AM
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I'd try chasing the threads with a tap first and see how that does. The insert you refer to is a heli coil, they work well although I've never used one on a spark plug.
Old 10-13-19, 04:28 AM
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Look at the threads real good obviously, but sure, if they look salvageable I'd try a chase. Slow and easy, make sure you have the lead where it needs to be, and unless you're going to take the head off put some grease in the opening and lead end to catch any chips. I've used Heli-coils a few times, not their biggest fan although they do have their place, but before buying that I would probably check the price for a new head. Maybe not valid, I don't know, but my concern with a Heli-coil in this case is that small engines get very hot, very fast, and I wonder how it would affect heat transfer and expansion and contraction.
Old 10-13-19, 01:42 PM
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I hope chasing the threads gets them back, if it doesnít donít do the heli coil. They suck. Youíd be better off finding a used cylinder head off eBay, or Iíve also heard of guys getting a larger spark plug, like the plug from a 350 Chevy, and tapping the hole put wider to accommodate.
Old 10-14-19, 04:39 PM
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Years back I made the mistake of applying seafoam on the spark plug threads before putting it back which resulted in a head replacement (DIY). That was 5 years ago, mower still going strong (Toro 2007).
Old 10-16-19, 12:05 AM
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Sav-A-Thread. Works well. If chasing the threads doesn't fix it (doubtful if it's really stripped all the way through the threads).

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