carb m38a1 repair bolts thread question

ktm25089 · Post by **ktm25089** » Sun Apr 10, 2016 11:00 am

Hello
im trying to rebuild my original carb from the A1 to get rid of the chinese crap solex.The major problem is that a genius have replaced two of the carb cover bolts 10/32 with wood screws!!!!!!So,the damage is the threads and a small crack in the wall of the one.Is there something that i can use to fill the holes and drill and tap new threads?
everyone i ask,they told me that the zinc cast they use for the carbs is not repailable and only cracks.

Thanks
George

Post by **wesk** » Sun Apr 10, 2016 11:07 am

Sometimes the naysayers are spot on and sometimes they are not. Just apply a wee bit of two part epoxy sealer to the inside of the cracked threaded hole. Then follow the directions with a 10/32 heli-coil kit and see how it works out.

ktm25089 · Post by **ktm25089** » Sun Apr 10, 2016 11:57 am

thanks wes
i will try and inform

Post by **wesk** » Sun Apr 10, 2016 12:29 pm

Don't rush the heli-coil kit's tap into the cracked hole. Take your time and remove it if needed to clean the thread chips up as often as you feel the pressure becoming exceedingly high. Do the un-cracked hole first so you can get a feel for the tap.. You don't want to enlarge the crack. In fact if you can easily see the crack itself then you may want to stop drill it with a drill smaller than 3/64ths.

scoutpilot · Post by **scoutpilot** » Sun Apr 10, 2016 2:39 pm

X2 on wesk’s advice. Take your sweet time. Double check the depth of the hole and tape the drill bit for that length at a maximum. Stop-drilling the crack at its end should work. You can use JB Weld to close it and the holes. Just let it cure for a MINIMUM of 24 hours before you attempt to drill out the holes. Two or three slow turns in with the tap and a couple back out to clear the swarf. Again take your time.

Rick
Scoutpilot
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ktm25089 · Post by **ktm25089** » Mon Apr 11, 2016 3:31 pm

thanks will inform

costecon · Post by **costecon** » Mon Dec 17, 2018 10:04 am

Hi, I have the same problem in one bolt. The thread has been stripped and the bolt was actually missing . I have no crack though.
I was thinking to close the hole completely with epoxy and then drill and make a new thread. Not helicoil or something, just a 10/32 tap.
Do you believe it will work?

Post by **wesk** » Mon Dec 17, 2018 10:41 am

Do you believe it will work?

No.

The epoxy will always yield to the steel bolt. The epoxy threads you made would strip easily with probably about half the torque used on one of the other bolts.

You permanently fix stripped threads by replacing them!