Perma-Coil installation

[Mr Mach1]

I have what I believe to be a Shovelhead generator with 5/16" threads for the mounting screws. My 49 requires 1/4". I bought the 1/4 24 perma-coils that were recommended but the won't screw in. Is there a special tool or technique? The post stated they would just screw in as they have the same thread as the 5/16".

[Cotten]

Mr Mach 1!

I am familiar with 'Heli-Coils', and 'Re-Coils' which are the same thing,
but "Perma-Coil" scares me.
Are they similar, or a "better idea"?

Ordinarily, an insert can be turned in with small needle-nosed pliers or forceps.
Try hacksawing a slot in the end of a piece of 3/16" stock like a little fork.

The end of a 1/4"-24 bolt can also be cut upon its with a hacksaw to make a driver, but it shouldn't be necessary; Patience and steady hand are.

...Cotten

[Mr Mach1]

Mr Mach 1!

I am familiar with 'Heli-Coils', and 'Re-Coils' which are the same thing,
but "Perma-Coil" scares me.
Are they similar, or a "better idea"?

Ordinarily, an insert can be turned in with small needle-nosed pliers or forceps.
Try hacksawing a slot in the end of a piece of 3/16" stock like a little fork.

The end of a 1/4"-24 bolt can also be cut upon its with a hacksaw to make a driver, but it shouldn't be necessary; Patience and steady hand are.

Perma-coia are just like heli-coils. Same design and appearence. I'll grind down a pair of needle nose pliers and try that.

...Cotten

[Cotten]

Mr. Mach 1!

I grind on pliers all the time too.

But just a gutter nail will do:

INSRTTUL.jpg (42.86 KiB) Viewed 2725 times

And with the head cut off, you can just turn it around backwards to knock off the tang.

I measured a Heli-Coil insert to be ~.322" OD ,.... just in case yours are not.

...Cotten

[Mr Mach1]

Well something ain't right. Normally I can just screw in an insert but this time it was really hard to get started and after I did I couldn't get the 1/4 24 screw in. I did it twice and still no good. The insert fits the screw just as it should but one in the generator its too tight.

[rd.king]

these are the question that pop into my head.
Are you sure the the hole is 5/16 24.
have you ran a 5/16 24 bolt through the hole.
maybe it's been gunked up with thread locker.
Did you clean the threads with a tap.

[Mr Mach1]

these are the question that pop into my head.
Are you sure the the hole is 5/16 24.
have you ran a 5/16 24 bolt through the hole.
maybe it's been gunked up with thread locker.
Did you clean the threads with a tap.

No I didn't. The studs screwed in the generator so easily I didn't think it was necessary but I'll do it.

[Cotten]

Mr Mach 1!

My concern, when it first dawned upon me that this could be done, many years ago,
was that the fit seemed on the loose side.


....Cotten

[FlatHeadSix]

Did you clean the threads with a tap.

the big question is; did you run the correct tap down the hole?

Most of those kits come with a special tap, you MUST run THAT tap down the hole before you try to put the insert in. If ya don't, it ain't gonna work, period!
jmho
mike

[Cotten]

Mike!

I assure you because I have both,
the 1/4"-24 Helicoil tap is if anything a minute bit smaller than an SAE 5/16"-24 tap, probably only to make it "proprietary" and expensive.
Although it is perhaps the only size of insert that resolves with a standard size, an ordinary 5/16"-24 tap does quite well.

Mr. Mach 1!

Did you mic the un-installed insert and compare it to the Helicoil's .322" diameter?

....Cotten
Late edit:
Because my veteran Helicoil tap has three flutes, I had to zero an indicator upon .3125" stock in my lathe chuck, and replace it with the taps for a radius comparison.

The well-used Helicoil tap was about three thou under, and a reasonably fresh SAE tap was a thou or two on the high side.

So a six or eight thou increase in OD is all it takes to give a 1/4" bolt a sloppy feel.

[Larry]

[quote="Cotten"]Mr Mach 1!

My concern, when it first dawned upon me that this could be done, many years ago,
was that the fit seemed on the loose side.


....Cotten[/quote]

The fit is terrible, and it's hard to believe that it works, but it does. Helicoils are really strong.

[Mr Mach1]

Mike!

I assure you because I have both,
the 1/4"-24 Helicoil tap is if anything a minute bit smaller than an SAE 5/16"-24 tap, probably only to make it "proprietary" and expensive.
Although it is perhaps the only size of insert that resolves with a standard size, an ordinary 5/16"-24 tap does quite well.

Mr. Mach 1!

Did you mic the un-installed insert and compare it to the Helicoil's .322" diameter?

....Cotten

No but tonight I'll mic it. I'll also run the tap down the holes and try again. Good thing the inserts are sold my the dozen. It's time I got back to work on it. I still have the engine & trans to tighten down after I install the inner primary then start installing the new harness. I'm kinda eager to hear it running without those DC-3 drag pipes.

[Igosplut]

Looking on a site that sells perma-coils, they work on the same principle as Helicoils....A thread insert. You have to drill out the mounting hole with the required size drill and tap with their special size tap so the insert will work properly (as stated in an above post).

Perma-coil

The only different thread repair Ive seen are Time-serts, and Big serts

This is a solid insert vers a stainless wire (helicoil, ect) insert. The Big serts are good for mounting holes that have been oversized for the helicoil style, or pulled helicoils (I've personally used them for shovelhead head bolts and they worked great).

[Mr Mach1]

OK, I mic'd the perma-coil to. 318 od. I taped the holes and blew them out. Still no good. Thinking I'll give up and use the long studs. I'll prep it for paint and spray it this weekend. Now on to the wiring.

[Igosplut]

If I'm not mistaken, the inserts (non-solid) are going to be larger (measure larger) than the tapped hole because their meant to expand after installation to keep them captive.