How can one repair A.I.R manifold tube threads?

[Rob A.]

Re: How can one repair A.I.R manifold tube threads

Greg,

As I said, I have the correct size tap and have used it, trust me, the size I posted is correct.

[Gerard F.]

Re: How can one repair A.I.R manifold tube threads

Greg,

Just a thought. Maybe it's pipe thread which is 18 per inch but tapered in 1/4" pipe size. Or maybe you can find a pipe coupling or nut with straight threads, at your local hardware store, that will fit the threads on the male part. Then just braze that coupling or nut to the inside of the manifold.

Just a thought. If it works, no one will ever know.

(Bubba) Jerry Fuccillo
#42179

[Greg L.]

Re: How can one repair A.I.R manifold tube threads

Joe, I measured the O/D of the tube nuts and get a measurement of .500" give or take few thou with no tapper, then I used my pitch gauge from my tap and die set and the 18 pitch gauge fits perfect. My next one up is 20 and it is way off but maybe the thread class is loose enough for a 19 pitch to work as well as Rob says.

On a side note I contacted Bill Hodel to see if he had ever repaired this type of thread and he said that he received a set from a guy that had heli-coils installed. This guy is a NCRS & Bloomington judge but I can't remember his name right now but Bill says I should contact him because the repair looked quite good.

I'll post how it turns out and if anyone has any other suggestions, I'd love to hear them.

[Mike McKown]

Re: How can one repair A.I.R manifold tube threads

Several years ago, I was looking for some stainless steel threaded plugs to screw into a set of BB manifolds that I had removed the air tubes from. Went through quite a search before I found some. I believe I was told they were 1/4 X 18 and that thread was used in refrigeration work. Might be a source for whatever??????????????

[Tracy C.]

Don't need no stink'in machine shop..

Wouldn't the best way to get the "center to center" dimensions be directly from the spider leg tubes that screw into the manifold?

If the holes to be repaired are pependicular to the head side of the manifold, then a simple drill press would be good enough to redrill the holes. Just layout the center points for the holes with a good 24" machinist's scale then plop that sucker down on the drill press table and make er smoke Bobby..

Got nutthin to loose what with all the discussion of buy'n new part and stuff..

good luck,
tc

[John H.]

Re: How can one repair A.I.R manifold tube threads

The GM manifold drawings show those holes as tapped 1/4"-18 NPSF (straight pipe threads).

[Greg L.]

Re: How can one repair A.I.R manifold tube threads

Hey John do you know what NPSF stands for? I did a google search to try and find a source for a tap or heli-coil repair kit and can't find one. Thought that if I could search the actual name and not just an abreviation that it might help.

[Mike McKown]

I don't even look like John, but

http://www.google.com/search?svnum=10&hl=en&safe=off&sa=N&resnum=0&q=national%20pipe%20straight&spell=1&tab=iw

This oughta' keep you busy for hours.

My guess is the F=flare and it's an attaching thread rather than a sealing thread.

[Mark #28455]

not perpendicular

They are drilled to direct the injection tubes at a downward angle into the ports.
Mark

[Tracy C.]

Then make a angled buck board by ripping

a 2 X 4 on edge along a table saw. It may take a couple of trys to get the correct angle on the blade, but it can be done.

never say die..