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View Full Version : Fix for Stripped Thread in Dist. Housing?


ghaegele
05-18-2009, 10:32 AM
The threads in the distributor housing that hold the distributor cap down are stripped on one side. Otherwise the housing is in perfect shape. I'm in the middle of a rebuild and am considering replacing the housing with an aftermarket. But one thing after another needs replacing and I'm wondering if there isn't a cheap fix for this. Can I fill the hole with JB weld and then drill and tap the right thread? Any thoughts on how long that will hold?

Thanks for any advice.

David Masury
05-18-2009, 12:30 PM
Since all you are doing is holding the distributro cap down, then JB weld should do just fine. There are several other types of epoxy blends that have metla in them that makes them a bit better for cutting threads in. Just make sure that you clean the are really well before bonding.

David

ghaegele
05-18-2009, 02:37 PM
Thanks, David. Is there a brand you would recommend? Greg

Baltimore Sailor
05-18-2009, 02:52 PM
Since it's just the cap, why not just drill out both holes and rethread them for the next larger screw?

ghaegele
05-18-2009, 02:59 PM
It's a minor detail but the distributor cap comes with the appropriate size screws partially seated. If I retap to a larger size I have to find the right size screw, remove the provided screw, expand the hole in the cap and reuse the screw every time I replace the cap. Not the greatest inconvenience, but then the inevitable screw falling into the bilge, etc., and it becomes a headache I'd rather avoid.

Don Moyer
05-18-2009, 03:22 PM
This would be a really good problem to solve, since we'll likely see more and more of these threads fail as the fleet continues to age.

My first thought would be to fill the hole with a small dab of epoxy from one of the small fiberglass repair kits from West Marine and then drill and re-tap the hole to the appropriate size - remembering that each side has a different size bolt hole.

Add enough of the glass dust to the epoxy to make it the consistency of mayonnaise, and then blow the hole out really well with carburetor cleaner first to make sure the epoxy has a good chance to bond well with the aluminum housing.

I'll be visiting our fabricating shop tomorrow and I'll try to remember to get the exact size of the bolts.

Don

ghaegele
05-19-2009, 09:04 AM
Don, thanks for the reminder on different sized bolts! I will keep the fleet posted on the success of the repair.

Don Moyer
05-20-2009, 02:07 PM
I did check and discovered that the large retaining bolt has standard 10/30 threads and the smaller bolt has standard 8/32 threads. You'll have to ask for "bottoming taps" in both cases since the holes are not all that deep.

Don

67c&ccorv
05-20-2009, 11:49 PM
I did check and discovered that the large retaining bolt has standard 10/30 threads and the smaller bolt has standard 8/32 threads. You'll have to ask for "bottoming taps" in both cases since the holes are not all that deep.

Don

Don, did you mean the large retaining bolt has "#10/32tpi" standard threads?

I have never heard of a standard #10/30 thread.:confused:

Regarding what type of filling material to use I am a big fan of using "easyserts" (may not be enough room on the housing for these) or using the glass-bedding material that armourers use to glass-bed M1 & M-14 rifle actions to wood stocks. www.Brownells.com Inc has a large selection of various acra-glass bedding material that use anything from aluminum powder to stainless steel powder to make a glass-bed material that you can cut threads in and will withstand the pounding of continuous high-power rifle recoil.

Don Moyer
05-21-2009, 07:05 AM
Sorry, I pressed a wrong key. The large bolt is 10/32. I forget what the correct drill size is for each of these taps, but the drill size is usually given on the tap itself.

Don

ghaegele
05-21-2009, 07:37 AM
Thanks all. I couldn't find anything on easyserts but quick-sert appears to be similar. By their literature there's just not enough metal around the housing to go expanding it enough for an insert. There is almost no tension on that bolt. I know that because for at least 4 years the bolt has held on by no more than 1/2 of a thread. (I actually had to reuse the bolt from an old cap each year that was slightly longer than all of the new ones and gave me that last 1/2 thread of purchase.)

marthur
05-21-2009, 08:38 AM
Here's another idea I have run across (but never tried): Loctite's Form a Thread thread repair kit. It appears that this can be torqued enough to keep your distributor cap on.

Here is a link to the data sheet: http://www.midwayusa.com/midwayusa/StaticPages/pdf/instructions/Loctite_stripped_threads.pdf

Good luck,

Mike

ghaegele
04-29-2012, 06:41 PM
The answer to how long the JB Weld repair will last is three years. Replacing the distributor cap this year and there was nothing left of the threads. I removed the distributor and will use Don's procedure (West epoxy with glass dust) this time. I'll check back in in a few years and let you know how long that repair lasts.

Mo
04-29-2012, 06:50 PM
heh heh....the joys of modern chemistry and a little thinking outside the box.;)

marthur
04-30-2012, 12:41 PM
Has anyone tried filling a hole with brazing rod or solder and then redrilling and tapping?

For aluminum parts there are several brands of repair rod that can be applied with a propane torch.

Although these products have a low melting point, they can be harder than epoxy and might make a more permanent repair.

ArtJ
04-30-2012, 01:02 PM
Wouldn't the dissimilar metal issue cause problems since the housing is
steel?

marthur
04-30-2012, 02:24 PM
It is possible, but I don't think it would be any worse than the galvanic corrosion between the bronze water pump and steel bolts used to mount it. Or between the copper washers used in a couple of places and the iron block.

If the repair is painted, would there be enough water and salt on the distributor to create an electrolytic cell? Perhaps someone with experience brazing engine parts could help us out.

If we are worried about corrosion, someone with a mig welder could weld the hole closed, drill and tap.

These are just ideas to get a material harder than epoxy into the hole.

ghaegele
04-30-2012, 03:40 PM
BTW, the housing is aluminum. Don't know if that effects the brazing/welding thoughts.

ghaegele
05-04-2012, 01:44 PM
Thanks, Marthur, for suggesting the aluminum repair. I looked into it and found Alumiweld from Harbor Freight. It comes in a rod that is melted with heat. I'll cover the whole procedure for others with a similar need. The back story is above. Here is a link to photos of the repair. Photos (https://picasaweb.google.com/ghaegele2/DistributorRepair?authuser=0&authkey=Gv1sRgCNb4rKCIjN3zdw&feat=directlink)

I first tested this product by filling a hole in an old aluminum backing plate, drilling and tapping it, and then screwing a bolt into it and whacking the snot out of it with a hammer. Neither the filler nor the threads were damaged.


Satisfied, I drilled out the old JB Welded thread until bare aluminum was showing and heated the housing with a torch until the Alumiweld rod melted in the bore and I filled the hole until there was a bead. I filed the bead flat, drilled and tapped to the correct thread (10-32). (Actually, as you can see from the photo below, there was a crack in the housing at the thread and when drilling the repair before tapping it, the drill jammed in the Alumiweld and twisted the repair in the bore, opening the crack slightly. So I then removed the repair, opened up the crack with a Dremel and refilled it, filling the enlarged crack at the same time, and then carefully drilled and retapped it. I also ran a larger tap into the bore before heating and melting the Alumiweld to give the repair more to grab on to.)

I am very confident that this repair is permanent and I am very impressed with Alumiweld. I would use it for any similar repair.

https://lh6.googleusercontent.com/-rKWzotff2Gg/T6QcDYE48YI/AAAAAAAADOE/Ltc5eK-VbiM/s912/IMG_2574.JPG

https://lh4.googleusercontent.com/-QiHLG0iUS9g/T6QcGnbhLaI/AAAAAAAADO0/kmHRHkgtOZE/s912/IMG_2591.JPG

marthur
05-04-2012, 01:53 PM
I'm glad this worked out! Looks like you did excellent work.