Mag post threads stripped out

[Steve Jelf]

Two years ago I discovered that the front magneto screw hole on my 1915 hogshead was stripped out. With no experience welding aluminum, I took the injured part to a shop and had the hole filled. I redrilled the hole, and ran a 10-32 tap through it. It was fine, and still is. Last week I removed the mag post to see if it needed cleaning. Nope. All it had on it was nice, clean oil. No trace of fuzz.

When I reinstalled the mag post I was vary careful not to over-tighten the screws, but the two rear ones both stripped out. I suspect they were already on the edge of failure and one more tightening finished them off. The previously repaired front hole is still fine.

So now my choices are to pull the hogshead and fix the two rear holes as I did the first one, or install helicoils, which I have never done. I'm inclined to go with the first choice. Am I on the right track?

[Adam]

Cheap easy way to do it: Turn the mag post maybe 1/12 of a turn and drill & tap new holes. Just make sure they are in a position you can get a screwdriver on. Or use socket head capscrews and a ball end key. No need to fill in original holes.

[Jerry VanOoteghem]

... or re-thread them to 12-24. You may need to enlarge the holes in the mag post if you go that route. The larger, course thread may be best in the long run.

[speedytinc]

Cheap easy way to do it: Turn the mag post maybe 1/12 of a turn and drill & tap new holes. Just make sure they are in a position you can get a screwdriver on. Or use socket head capscrews and a ball end key. No need to fill in original holes.

Now thats a brilliant fix for now. Next time you have the HH off weld the holes up.
My fix would have been a helicoil or keensert.

[mtntee20]

I would NOT recommend Helicoil inserts on an aluminum hogs head. The reason: When the Helicoil is inserted, the last step is to break off the tang on the bottom of the Helicoil. Being as the Helicoil is steel, there is a huge chance of dropping that tang into the engine/transmission. A much better option is a Time-sert. It's solid and has nothing to fall into the engine/transmission.

Steve, I know you are able to drill. I also know you are able to tap threads. Thus, YOU are completely able to insert a Time-sert to repair threads. I see the biggest problem is keeping the drill and tap swarf OUT of the engine. A vacuum cleaner might work just fine. The swarf will be aluminum but you still do NOT want that in the engine.

Good Luck,

[Ken Buhler]

Sometimes you can slip a small gauge solid copper wire in the hole leaving a tail hanging out and then run the screw in beside it. Snip the tail off after it's tight. We do that when attaching a temporary block to concrete. Drill the concrete, slide in a piece of rebar wire and nail. The nail will hold strong and yet be removable.

[speedytinc]

A smart guy could rig a bit of double sided tape on a wire fed thru the contact hole to catch the break away teet.
I agree foreign matter should not be introduced. I believe helicoils are non magnetic SS.
A smart fellow could also rig a bit of tubing to a vacuum to go thru the contact hole to suck up the aluminum drill chips.
I would do what ever to not remove a HH.

[Scott_Conger]

Prize for best advice in this case should be shared between Terry and Adam. Terry, for a significant catch for the potential of introducing FOD into the transmission, and Adam for simple cleverness...

[Allan]

I'd vote for Jerry's larger screws. Drilling the holes with the cover in-situ and getting the holes square to the face will be nigh on impossible. Re-tapping existing holes gets around this. Grease on the tap will capture swarf, and re-applying same will capture more as you tap the holes.

Allan from down under.

[Norman Kling]

How often do you check for lint in the mag plug? Over 100 years it must have been taken off and put on many times maybe over 100! No wonder the threads were bad. I haven't had a problem, however my cars all have steel hogs heads and I only remove the plug if I am having problems with the magneto or when I pull the hogs head or the engine.
I think you have had some good ideas posted above. Good Luck hope you can get a long term fix.
Norm

[Scott_Conger]

Going with 12-24 threads runs, I think, a real risk of not having sufficient room for the head of the screw. I'm not holding a mag post in my hand right now, but think I recall having to be pretty selective in the screws used to fit original pickups and there was no spare room for any increase in the head diameter.

think this thing through and consider all ramifications of the choice you make.

[John kuehn]

Maybe retap the stripped holes to the next size. Or as Adam said turn it and retap to original size. Stuff a rag just under the hole and carefully redrill or tap.
The next time you have to remove the cover then maybe reweld the holes and drill and tap it.
Good luck and remember to not overtighten the screws since your cover is aluminum.

Or use the next size self tapping metal screw but most on here would frown on that. But it would work.

[Rich Eagle]

Mine were pretty bad. I tapped them to a bigger size and JB welded in threaded brass plugs. (2015) Then tapped the new holes. It has worked fine so far.
Rich

[Jack Putnam, in Ohio]

Drill and tap. 12 x 24 as said before.

[ModelTWoods]

You had good luck with one. Don't Mess with Success.

[Craig Leach]

Hi Steve,
Just some notes. If you retap to 12-24 do what you can to capture the tap cuttings. Put something thats oily or greasy in the hogshead that will
catch the the cuttings ( that will be easy to get out) & grease the tap to catch some more cuttings. you will likely need to drill out the holes in
the mag post & you can file or grind down the O.D. of the screw head so it fits if needed. Removing the hogshead is not fun on any T ( not that
tapping those holes will not be a P.I.T.B.
Good Luck.
Craig.

[Jerry VanOoteghem]

I think if you apply some shop-vac suction to the mag hole while drilling/tapping, you'd probably pick up most of the chips.

[Adam]

When I gave my advice regarding turning the post 1/12 turn and re-drilling/tapping new holes; I guess I should have specifed that it should ONLY be done with the HOGSHEAD OFF THE CAR. Sometimes I forget there are some basic common-sense aspects of repair that everyone doesn’t share.

[Chris Barker]

Is it possible to insert, via the trans cover hole, 10-32 screws UP through the damaged holes, held by adhesive, and then put nuts on top?

[speedytinc]

Is it possible to insert, via the trans cover hole, 10-32 screws UP through the damaged holes, held by adhesive, and then put nuts on top?

No. You wont get past the flywheel to get to the field coil obstruction.