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ambler

Helicoil repair

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ambler
was firing up a 3212H after sitting a year and went to put a little gas in the plug hole. Felt a little wobbly and foungd it stripped. Put a good head on it today and she fired right up. I would like to repair the old head. What size helicoil do I use? My search didn't turn up specs. I will locktite it. Thanks

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UCD
I believe all small shank plugs are 14mm and large are 18mm. The parts stores have Helicoil kits just for spark plug repair. Rule of thumb is if it takes a 5/8" s/p socket to remove it is 14mm if it takes a 13/16 s/p socket it is 18mm.

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Roy
"Rule of thumb is if it takes a 5/8" s/p socket to remove it is 14mm if it takes a 13/16 s/p socket it is 18mm." Not necessarily. 5/8" and 3/4" plugs are relatively new (last 20 years or so?). In the past, except for Fords, most cars ran/run 14 mm plugs that take a 13/16" socket wrench. Fords ran 18 mm plugs that also take a 13/16" socket. A Champion J-8 in Briggs engines is a good example of a 14 mm plug that takes a 13/16" wrench.

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DanD
I just looked at Jacks parts database and a brand new head for a 16 hp 326431 Briggs is $58.71. Should be less for this smaller engine. Don't think I'd spend $85 or even $35! Of course, shipping will add a little but it's not too bad from them.

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HubbardRA
Ambler, A "true" high compression head will make a very noticeable difference in the operation of the engine. When tractor pulling, I took the small combustion chamber head from a 10 Hp Kohler, then milled 0.060 off of it, and ran it on a 14 Hp engine. Major increase in power. With the work I did on it, I was expecting about 1 1/2 Hp increase. From the way the tractor felt when pulling, I think we got at least that much. Just remember that when you start raising the compression, the engine will run quite a bit hotter. I was running one trip down a track then shutting the engine down. I don't think I would try this on a real worker, because it would probably cause overheating problems. Most likely result would be warped head or burned valves because on the lack of uniformity in the way the combustion creates the heat in the chamber. There are some very hot spots around the valves. In fact, the factory uses this effect to help keep the exhaust valve clean.

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rsnik
The plug blew on the 2010 I bought a while back. The hood was off. Loud pop like a gun going off and the plug flew so far into the air it literally went out of sight and I yelled at the guy with me to take cover as I thought the plug could cause injury if it hit you, falling from such a great height. A guy at the fix-it shop referred me to his guy at Napa who sold a repair kit for $35. It's not a helicoil. It is what looks like maybe an 18mm insert that screws in (some locktite is provided) with a 14mm threaded hole in the insert. A tap with a tapered ream at it's base is provided which supposedly removes material until the hole is enlarged to the point that the tap engages and cuts new threads. I tried it and it seems to me that way too much material has to be removed. I used Marvel Mystery oil as a cutting oil and sucked out the metal debris with a special vacuum attachment and finally said "nuts to this". The ream is wearing out before I am making much progress and I get the strong feeling I should remove the head to do this so as not to leave metal debris in the cylinder. I have been looking for a used, 10 HP head on eBay for weeks but none has shown up. After reading this post I realize what I should have done is pulled the head and shipped it to Al Eden! :(

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