View Full Version : Freeze Plugs

Lark Parker
08-27-2006, 08:25 AM
Freeze plugs, expansion plugs, casting plugs, or whatever you want to call them
are different for different engines. Brass plugs for the Stude V8 in 1962-64
with full flow oil filter blocks take a "cup" type plug, P/N 1550386. The
1951-61 and 1962 blocks without full flow filters take a "disc" type plug, P/N
1539038. This "disc" type plug also fits 1934-62 Commanders, Presidents, 6, 8,
and V8, and 1939-60 Champ[ion]s.
For some reason, there are different size plugs for the 1961-64 6-cylinder Champ
engines. The ones that take a l 1/2" are the same as the 1962 '64 V8's. The
other is a 1 7/8" with P/N 1550433 and is listed for 1939-64 Champs. This all
may sound confusing and, if not, we could throw in the rear plug at the back end
of the camshaft. For instance, the 1951-62 V8's use a 1 1/2 "disc@ (same as the
three on each side of the water jackets on the side of the block) and the
1962-64 also takes a l 1/2", but is a "shallow cup" and is steel instead of
The 1939-58 Champ[ion] takes a l 3/4" steel "cup" and the 1959-64 takes a
149/64" steel "shallow cup." If you're still not confused, consider the oil
gallery at the left end of the V8 block that takes a 1 1/4" plug. Again, the
1962-64 takes a "cup" and the earlier V8's take a "disc" type. Both of these are
steel. In reality, any of the brass could be steel and vice versa.- just that
the brass will last longer by resisting rust The main thing is to use the
correct "cup" or "disc" (and size, of course) for your engine. The recess is
deeper on the late models and trouble comes when you try to use the "cup" type
on the earlier models that take the "disc". The "cup" may pop out as they will
not go in as far as they do on the late models.

Thanks to TED HARBIT for this information that was found in the June 1999 issue
of the BRICKYARD BULLETIN, Dale McPhearson, editor

Lark Parker
aka Trim Trader
Frankfort IN

08-27-2006, 08:48 AM
Thanks for that information. I've used the copper, expandable, Dorman type, in my 55. They used to be Dorman DC-9, but someone bought them out and now they're being made in, "guess where". They aren't made as well as the original Dorman, but still work well. The latest numbers I have are NAPA/Balkamp 600-4027 or Dorman 568-009.
My 55 engine has a land inside the core hole, so the plug sits on the ridge and you can easily crank the nut tight. I'll presume the full flow engines do not have anything but a hole, since my 64 has a deep cup installed.

08-27-2006, 11:43 AM
I've always felt that it was wise to use a cup in place of a disc wherever possible. The outer edge is what holds the plug in place; the width of that edge is 1/4" or more on the cup, as opposed to 1/32" or so with the disc- therefore better (stronger) holding ability...

Yes, they're not show-correct, and if the don't go all the way flush, they're not very attractive... but if they're hidden, I feel it's the best way to go...

Not so?

Robert K. Andrews Owner- IoMT (Island of Misfit Toys!)
Parish, central NY 13131

08-27-2006, 01:28 PM
Robert; NO, not so! while you do have a wider surface on the cup type, you only can use the small narrow 1/8in. ridge in the the block to seal on the plug. Also the bevel on the inside corner of the cup reduces the sealing surface even more. But that is not the main reason why I will not use the wrong plug. The design of the disc type is concave to tighten when flatened. Whereas the cup seals by being a force fit on the wide outer edge, it does not have enough block surface to seal on because of the ridge. The very small edge of the disc type will TIGHTEN much more and NOT blow out, if you install it with the proper seal driver so as to get it very flat! [^]
Don't forget the Studebaker "Perfect Seal" gasket cement! LOL:D[^] -Just use aviation gasket sealer, since not many of us still have any Perfect Seal, my (2) cans are almost gone!:(

Studebakers Northwest
Ferndale, WA

08-27-2006, 03:02 PM
Thanks, Lark & Ted ;) And I'm with Rich on this one.:D

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

08-27-2006, 04:36 PM
Huh.. learn something new every day!

I've never had a problem with one, but hereforth I will use what I've learned in this thread... Thanks Rich!!

Robert K. Andrews Owner- IoMT (Island of Misfit Toys!)
Parish, central NY 13131

08-27-2006, 10:14 PM
WUOOPS!![:0] I forgot the gasket sealer! Should I remove them and do it over again? The front clip is still off.

Lotsa Larks!
K.I.S.S. Keep It Simple Studebaker!
Ron Smith

08-28-2006, 01:10 AM
Rather than pull the core plugs out, remove the thermostat, cap the lower radiator hose and heater hoses, put 20psi air pressure over the water in the block. I use a section of inner tube with the valve stem in it on top and a blank section on the bottom, held on with a couple of hose clamps. If it holds 20psi for an hour or so, you have a seal. Heat does make a difference, but if it is going to leak, the air pressure should find it for you.

thnx, jv.