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I don't want to put too much into this old lawn mower. The threads stripped in one of the bolt holes for the intake. I don't have a tap and die set, but I can try to purchase one from Harbor Freight. I also read about Heli coil inserts. What is the least expensive way to repair this? Do you think it will hold if I just use RTV gasket and use a single bolt?

The bolt looks like it is a 1/4-20 x 1

what kind of engine are you working on?

See what the next size up is in a metric bolt. Most hardware stores have individual metric taps and the bit needed together.

Scrubcadet10 said:

what kind of engine are you working on?

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It's a Tecumseh 100-10079d

A few ways to fix it.

Or go up to 5/16 self tapping screw

Or the poor man's route of grinding a slight taper on the end of the original bolt and put a couple of pieces of 16 or 18ga. Solid copper wire in the hole and crank the bolt in wedging the wires into the threads.

I noticed the threads came out (at least the top half of them did). Do they sell those self tapping screws locally?

What are your thoughts on this?

I'm guessing I would have to drill it out and tap it with the 5/16."

Forget the HFT tap and die sets. I purchased both a metric and SAE sets. They were so poorly made I return them as soon as opened them up.

bluefitness said:

I noticed the threads came out (at least the top half of them did). Do they sell those self tapping screws locally?

What are your thoughts on this?

Carbon Steel SAE Tap and Die Set, 21 Piece

Amazing deals on this 21Pc Carbon Steel Sae Tap And Die Set at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I'm guessing I would have to drill it out and tap it with the 5/16."

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A good hardware store should have them. Go up to whatever is just bigger than what you have be it SAE or metric and you should be able to cut in new threads without drilling.

Sets are waste of time and carbon steel ones ever a bigger waste of time , money & the resources of the planet
To do what you want you will need either a second tap & a bottom tap so there will be no threads down the bottom of the hole .
Extreme care is needed as the holes run close to the hole for the air:fuel supply and if you drill into that you are in for an expensive repair using solid air tight inserts .
The copper wire usually works if there is sufficient thread root to anchor the copper wire.
You might need to do it a dozen times before you get enough in there to hold as you have to do it a little at a time.
This was a common repair to motorcycle magneto points, where the steel thread went into the zinc arm .
Lots of goos , make a thread etc that do work IF YOU READ & FOLLOW THE INSTRUCTIONS which sems to be beyond the mental capacity of 99.9 % of the people who use it.

Take a close look at the hole. Are there any threads left at the bottom of the hole? Put a stud in completely to the bottom, then put a nut on to hold carb. Or put the stud in with some JB weld, leave it sit overnight. Sometimes put a strip of small dia. solder down the hole and force the bolt in.

Just get some duct tape and wrap the engine up like a mummy.... Normally any job worth doing is worth doing right...

bluefitness said:

I noticed the threads came out (at least the top half of them did). Do they sell those self tapping screws locally?

What are your thoughts on this?

Carbon Steel SAE Tap and Die Set, 21 Piece

Amazing deals on this 21Pc Carbon Steel Sae Tap And Die Set at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I'm guessing I would have to drill it out and tap it with the 5/16."

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That set is just trash. Not worth carrying to the trash can.

Hammermechanicman said:

That set is just trash. Not worth carrying to the trash can.

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the trash can is worth more than that set

Scrubcadet10 said:

the trash can is worth more than that set

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You got that right. The last Brute 44 gallon can I bought was around $50.

That's 5 HF tap and die sets...!

And if you don't know the trick of keeping a tap from sticking in aluminum you can break off one which is even worst to get out.

Don't you you chuck it in an impact driver and go to town?

Only if you want them to break. I broke several hand taps on the years before the machinist told me about the trick. Drilling out broken taps with carbide is not fun. Those broken tap extractors are a joke as I broken several of them too trying to remove seized and broken taps.

Hint its not oiling the taps either which works fine on steel and iron. It is another lubricate not usually used as a lube as but as cleaner.

When i tap aluminum if using a 4 flute tap i reverse and break the chip every 1/4 turn. 3 flute taps get 1/3 turn and reversed. I usually use WD40 instead of TapMagic on aluminum. Takes a while to get the feel. Most folks think you can just crank it in like a spiral turbo tap. Aluminum likes to gall and bind taps like taping some plastics. Been quite a few years since i neede a tap extractor. I still have a cigar box with taps in it the my father used working for the 3C during the depression. Being a government job when the program was over they gave all the mechanics and millwrights the tools they were using.