Flathead V8 Welch Plugs

[sth65pac]

Tony,

Questions/clarification :

Are you saying you need to tap a thread into the hole and then fit a threaded plug? I presume you would have to use some red silicone sealant to provide a gas/watertight seal.

How long is the 3/4 UNC allen plug? 1/4"? Is it a standard length.

I have this task ahead of me in the next few weeks. My engine is 'resting' on the garage floor now.....

Ian

[Keith Webb]

...for all the suggestions and help. I measured 18mm but I think 3/4" would make sense. There is only a small lip in which to nest them which is why the originals are dished rather than cupped. It's interesting just the sump gasket managed to seal this in the past - but there was a lot of gunk built up in there.

Tony, have you tried the allen plugs? I would have thought they were too deep to fit.

[Bob Moseley (RIP)]

Thanks for your comment Tony. I cannot believe the lack of knowledge of such a basic engine componant, although I must admit I haven't heard of or seen an Allen Plug. Welch plugs are readily available but if possible try to obtain the brass ones as most originals were steel. They are simple to fit, merely place them in the hole in the block with the concave surface to the outside and then expand the plug using a hammer and a drift. A touch of gasket cement around the edge of the hole wouldn't go ammis either. In the meantime read my thread on these or get that thread linked.

Bob

[Keith Webb]

OK... I found Automotive Surplus in Mitcham was open and they keep a range of welch in stock. Interestingly they said they had sold some to somebody else recently who had the same situation - two were missing when the sump was removed.

3/4" is the correct size, thanks Tony.

So the sump is now back on... the next job is to attack the water pumps with a press. Has anyone had experience in pressing water pumps apart? I'm thinking a bit of heat on the pulley and impeller might not go astray.

[Keith Webb]

So far managed to break the casting on one pump. Might wait for someone more expert to have a go at it.

Here's a shot of the new welch plug.

[John Stokes]

Originally Posted by Keith Webb

So far managed to break the casting on one pump. Might wait for someone more expert to have a go at it.

Here's a shot of the new welch plug.

Hi Keith your welch plug looks like it is up side down ? Thanks for the parts i have nearly finished the transfer case ,shift tower and linkages hope it rains tomorrow so i can stay in the shed catch up soon. John Stokes

[Tony Smith]

As in the post mentioned/linked above, I mentioned in 2004 that one of the engines I have has had the holes TAPPED for Allen Plugs. I'm only guessing (not sitting here in front of me ) that they were UNC thread, they could have been NPT, but find what plugs you can and tap that thread to suit. There is more than sufficient metal in the threads to tap into, and part of the plugs protrude into the water jacket, but they dont get in the way of anything.

Ian, you wouldn't need to seal the thread so much from leakage, as the sump gasket and some RTV Silicone would cover it, but more so as a corrosion inhibitor/antiseize to allow you to take the plugs out easily as often as you want to clean out the crud in the bottom of your water jackets. I'd guess you'd use the same thread sealer (Loctite, etc) that you would use on those head studs that thread into the water jacket from the top.

[Keith Webb]

Originally Posted by John Stokes

Hi Keith your welch plug looks like it is up side down ? Thanks for the parts i have nearly finished the transfer case ,shift tower and linkages hope it rains tomorrow so i can stay in the shed catch up soon. John Stokes

Hi John
No, it's the right way up - it's dished, not cupped, so it goes in with the convex side up which is then hit with a hammer and drift so it spreads to fill the hole.
Tony... there were no threads, just a shoulder for it to be fitted.