C2(66) Big Block Radiator Brass Plug Question

[Larry E.]

Working on my 66 L72 Convertible. When installing the Brass Plug into the Brass
Radiator should some type of sealer be used or should the plug be installed bare?
If sealer is used; which one should be used? Please give the names.
Thanks in Advance>Larry

[Jim L.]

Re: C2(66) Big Block Radiator Brass Plug Question

For pipe threads, Teflon paste is always a good choice. If the judging manual sez there shouldn't be any sealer, you can carefully wipe off the excess and no one will be any the wiser.

[Larry E.]

Re: C2(66) Big Block Radiator Brass Plug Question

Follow Up question for Jim or anybody else that wants to chime in:

To get the best seal for the above does it make a difference when applying should the
Teflon Paste go on the threads of the the Plug or on the threads inside the
radiator where the plugs goes?? Or to both?? It seems to me that if the sealer
only goes on the plug most of it is gone by the time the plug is in the
deepest part of the radiator threads. Or am I making too much of this and it
really does not matter. Thanks>Larry

[Larry E.]

Re: C2(66) Big Block Radiator Brass Plug Question

Anybody?? Thanks>larry

[Jim L.]

Re: C2(66) Big Block Radiator Brass Plug Question

Follow Up question for Jim or anybody else that wants to chime in:

To get the best seal for the above does it make a difference when applying should the
Teflon Paste go on the threads of the the Plug or on the threads inside the
radiator where the plugs goes?? Or to both?? It seems to me that if the sealer
only goes on the plug most of it is gone by the time the plug is in the
deepest part of the radiator threads. Or am I making too much of this and it
really does not matter. Thanks>Larry

I apply Teflon paste to the male threads because they are convenient but it doesn't matter which you choose. The wedging action of tapered pipe threads will wipe away the sealer anyway.

[Larry E.]

Re: C2(66) Big Block Radiator Brass Plug Question

I apply Teflon paste to the male threads because they are convenient but it doesn't matter which you choose. The wedging action of tapered pipe threads will wipe away the sealer anyway.

Jim:Thanks for response. OK will do the male threads. Still kinda confused on how this sealer works when like you
said the wedging action wipes the sealer away anyway but will use it. Jim>Is there any recommended "curing" time for this sealer
(Teflon Paste)? Since it will be sealing Anti-Freeze under 15# PRESSURE I think I will let set for a 24 hr. period.
Thanks Again>Larry

[Duke W.]

Re: C2(66) Big Block Radiator Brass Plug Question

I use "pipe dope" on NPT threads that carry water or steam. It acts as both a sealer and anti-seize compound. I can't recall any brand names, but any hardware store should know what "pipe dope" means and have it in stock.

Dile

[Mike T.]

Re: C2(66) Big Block Radiator Brass Plug Question

Larry - Back when I was in my Sheetmetal Apprenticeship at a local Navy Shipyard, they talked about the different qualities of
mechanical fasteners and most of the fasteners we used were listed as 2B for their class of fit for thread engagement. Not quite sure how to explain it (because it's been a very long time since those classes) but even when fully tightened, there is still some gap or void areas still remaining between the threads and sealants like Teflon Paste and Pipe Dope, fill those voids, minimizing leakage past the threads.

[Joe L.]

Re: C2(66) Big Block Radiator Brass Plug Question

Working on my 66 L72 Convertible. When installing the Brass Plug into the Brass
Radiator should some type of sealer be used or should the plug be installed bare?
If sealer is used; which one should be used? Please give the names.
Thanks in Advance>Larry

Larry------

The plug and associated radiator threads were "Dryseal" threads (i.e. NPTF) and not standard pipe threads (i.e. NPT). No sealer is necessary with NPTF threads and none was used in PRODUCTION. Just be sure that the plug you use has NPTF threads. The original plug, GM #444819, was never available in SERVICE. Of course, applying some sort of sealer to the threads will not hurt anything but it should not be necessary.

[Mike T.]

Re: C2(66) Big Block Radiator Brass Plug Question

Joe - that's interesting, I did not know that. Are the NPTF threaded plugs commonly available? Would an NPT plug seal well in the NPTF radiator threads or does the slight mismatch mean a bit of sealant on the threads might be needed?

[Joe L.]

Re: C2(66) Big Block Radiator Brass Plug Question

Joe - that's interesting, I did not know that. Are the NPTF threaded plugs commonly available? Would an NPT plug seal well in the NPTF radiator threads or does the slight mismatch mean a bit of sealant on the threads might be needed?

Mike------


Easily available if not from a local source (like an auto parts or hardware store), available from sources like McMaster-Carr ($2.27/each).

You could use a standard NPT plug with sealer.

https://www.mcmaster.com/4757T71/

[Larry E.]

Re: C2(66) Big Block Radiator Brass Plug Question

Larry------

The plug and associated radiator threads were "Dryseal" threads (i.e. NPTF) and not standard pipe threads (i.e. NPT). No sealer is necessary with NPTF threads and none was used in PRODUCTION. Just be sure that the plug you use has NPTF threads. The original plug, GM #444819, was never available in SERVICE. Of course, applying some sort of sealer to the threads will not hurt anything but it should not be necessary.

Hay Joe: Thank you very much on your input; you teach me something new everyday! AFAIK the plug is the original to the car.
Can you tell me how the threads are different from a NPTF and the NPT? I recently bought a few extra Brass Radiator Plugs
for a 66 Big Block from Corvette Central just to have some extra's on hand. I just assumed they where the regular NPT which
they may or may not be.. So what I hearing from you the two type of threads ARE NOT INTERCHANGEABLE. CORRECT?
Thanks again Joe; Larry

Just read the above thread to indicate they (NPT) would work with sealer. Thanks

[Joe L.]

Re: C2(66) Big Block Radiator Brass Plug Question

Hay Joe: Thank you very much on your input; you teach me something new everyday! AFAIK the plug is the original to the car.
Can you tell me how the threads are different from a NPTF and the NPT? I recently bought a few extra Brass Radiator Plugs
for a 66 Big Block from Corvette Central just to have some extra's on hand. I just assumed they where the regular NPT which
they may or may not be.. So what I hearing from you the two type of threads ARE NOT INTERCHANGEABLE. CORRECT?
Thanks again Joe; Larry

Just read the above thread to indicate they (NPT) would work with sealer. Thanks

Larry-------


I've never been able to tell the difference by just looking at them. Perhaps, side-by-side and/or under magnification the difference would be discernible.

[Larry E.]

Re: C2(66) Big Block Radiator Brass Plug Question

Found this picture to show the difference. Larry

[Joe L.]

Re: C2(66) Big Block Radiator Brass Plug Question

Found this picture to show the difference. Larry

Larry-------


I believe the taper for the NPT thread is exaggerated in the diagram. I don't think there would be that obvious a difference between NPT and NPTF in "real life", especially in the case of 1/8" . Also, NPTF is not straight thread; it is tapered.