The Stovebolt Site Forums The Shop Area Engine Shop Stripped threads in carb housing, Heli-Coiling OK?

Got an issue with one of my Holleys on the '55. Been having a recurrent leak at the feul inlet, snugging up the fitting always seems to stop it for a while. Today, I noticed a slight feul smell, and sure enough, it was a bit loose. Tried to tighten it, but it wouldn't snug up at all. I took the fitting out, the threads are bunged up pretty good. I was considering Heli-Coiling it. Is this a good idea? I don't think leakage will be an issue, as it seals with a copper washer gasket. Opinions are appreciated.
BTW, this is a Holley 1904 single bbl originally from an International truck.

....when your at the end of your rope you dril and uae a heli-coil, or go looking for new parts, or good used, parts.

I would install a heli-coil to get by while I was looking for a better carb core.

The heli-coil will be many times better than the original was when the threads were brand new. Where there is high thread wear, like the cover bolts on a quick change rear end, we install heli-coils before using. Many of the aircraft aluminum or other alloy parts have heli-coils in every hole.

Don't they sell an oversize inlet fitting to repair that problem?

I repaired a Ford Motorcraft carburetor recently with the same problem. That one used a readily-available thread, a 1/2"-20. It will depend on whether the thread on the fuel inlet is a size that a Heli-Coil is made for, or something oddball.
Jerry

Thanks for input, guys. I've done plenty of helicoils in te past, just never in a carb housing. The threads are 1/2-20.
Dave, I'm going to holding off on the repair until Monday, when I can go to the local parts storer instead of the chain sotres, as they are also a Holley dealer. I'll ask about the oversize fitting.

Bill, I drilled and tapped one from a 5/16 to 3/8 once and that fixed the problem perfectly. I'm not familiar with the Holley carbs, so that may not be an option. 1/2" seems large for a fuel inlet compared to what I usually work with and I don't know if 9/16" is an option.

Jeff

That's what had me concerned, as the material around the fitting is a bit on the thin side.

Just a follow up; Got the helicoil job done. Not real proud of myself on it, as I ended up a little off when I drilled and tapped, but afer dressing the gasket seat to match the off angle, it sealed up fine. I do plan on hunting up some extra cores next time I hit the salvage yards. Fortunatly, I have several in my area that do not crush old tin.

Glad you got it fixed.

The following is just information and not directed at you.

The issue of stripping threads in many carburetor fuel inlets can be avoided by using two wrenches when installing/removing the fuel line. One wrench holds the fuel fitting, the other turns the fitting on the fuel line. Failure to use two wrenches will eventually lead to the softer alloy threads in the carb body becoming stripped.

Hopefully, this technique will help others.

And the helicoil, if available in the needed size, IS the court of last resort.

Jon.

No offence taken by me, Jon. I beleive the threads were a little iffy on that carb to begine with, who knows what had been done to it before I got my hands on it.

From Rochester:

http://www.thecarburetorshop.com/QJetcartoon.jpg

Jon.