Two float bowl screw holes in an expensive (and not available as a separate part) carb main body I have were already helicoiled, but the person who did the repairs did a crappy job and now the inserts themselves have pulled out. I tried replacing the inserts, but one of the two new ones simply pulled out again, because there are simply not enough threads left over the length of the insert. So... anybody every run oversize float bowl screws in this situation?

It looks like my next size-up options are 6mm x 1, 1/4 x 20 or 1/4 x 28. I'd prefer to go w/ 6mm (smallest change) but the existing holes in the main body are already about .020" larger than the pre-tapping drill bit size and I'm concerned the result would be the tapped threads for the larger inserts might not have enough "meat" to engage properly with.

The concern w/ either of the the 1/4" options is that float bowl would need to be opened up "that much more" for proper clearance for the oversize bolts, and the metering block might also require clearancing. It would be nice to fix the issue w/o having to on more parts than necessary.

I use these a lot. I might even have the kit for the size you need at the shop. If I do, I will send it to you. They work pretty well on wallowed out holes like you are describing. Might be worth a try??

http://www.timesert.com/

MB

Check these guys out... every time something falls off of one of my carbs and will not tighten back up they save me!

http://www.blp.com/frmCatalog.htm

Unfortunately, the "oversize" re-coil kits aren't available in a 12-24 thread size and the special 1-piece inserts use the same size taps as the helicoils which pulled out the threads.

I'm wondering if I can re-install new 12-24 helicoils w/ red loctite into the very bottom of the holes and run longer bolts that reach into where there are still threads to hold the inserts...

"I do something similar to that. drill and tap, install aluminum bolt with loctite 271. cut off flush. drill and tap to original size."

I wouldn't hesitate to do this even if I had to use a steel bolt.

Another update: there were simply not enough threads left in the original tapped holes for the 12-24 helicoil inserts to stay put. I gave up on that idea, up-sized the two stripped holes to M6 x 1.0 inserts and ordered some M6 socket-head cap screws to use.

I did give some thought to the drilled & tapped aluminum bolt approach, but was concerned the aluminum would be more strip-prone than the carb main body itself. In the end, I decided to go for reliability, rather than being able to maintain the OEM-size bolts.