Engine: V8 threaded plugs in the sides of the block.

[PackardV8]

Building an R1 for a friend, prepping the block after machining, we always run taps down every threaded hole. On each side of the block, toward the rear, there is a 3/8" NPT hole to be sealed by a pipe plug from the small parts kit. While cleaning up the left side hole with a pipe tap, there were only about two threads there. Use enough sealer, might have gotten away with it; but it's the little things which can bite.

Take an 11/16" drill, bore it out and tap it for 1/2" NPT threads. With that, we now have at least six new, clean threads into the side of the block. Source a new 1/2" pipe plug that will never leak.

jack vines

[M-Webb]

I just ordered a thread chasing set for my 289 project last night to do the exact same thing.

And oddly enough, I was just looking at those plugs on my block today, wondering what they were there for. I assume they go into the water jacket. Instead of a plug, I was wondering if it was a worthwhile idea to change them to some sort of fitting to make it a lot easier and less messy to drain and flush out the block every few years to keep that nice and clean.

Looking at mine though, I could be wrong, but it looks like the ones in my block are already about 1/2", maybe even bigger. Sounds like they were originally smaller?

[DEEPNHOCK]

On my Dad's '61 Hawk... He put little brass quarter turn petcocks in there.
Old farmer stuff to drain the block dry over the winter.

[Jeffry Cassel]

Possibly not a good idea as this is where all the gunk gets deposited and a petcock would just get clogged up. Re-tap the hole and put in a nice brass fitting.

[PackardV8]

Possibly not a good idea as this is where all the gunk gets deposited and a petcock would just get clogged up. Re-tap the hole and put in a nice brass fitting.

For true, Jeffry.

Back when I still crawled under Studes regularly, I made a right angle fitting to screw into that threaded hole and a straight pipe with a hose bib on it to screw into that one. Any Stude V8 I worked on, I'd remove the threaded plugs, screw in the adapter, remove the radiator hoses and run high pressure water through the block. It was always amazing how much ditch water would come out of back there.

jack vines

[M-Webb]

Jack, that is pretty much what I was thinking. Putting a fitting there to attach a hose to so that when flushing it out, there is a way to control the out going flow and contain it so it doesn't just flood out all over everything and make a giant mess - have been there and done that. After I was done, it was a huge mess to clean up. Plus you need to remove the starter to keep that from getting flooded out too. But anyway, the motor I have now is a fresh clean block, so think will just skip it, hope I never have to deal with it. Just use proper coolant as Joe mentions and will anyway, hope it never becomes a big enough problem to have to deal with.

[JoeHall]

For M-Web, I would be very careful running a thread chaser through a pipe threaded hole. The one you show is 3/8" pipe thread, and all others external ones in the block are 1/8". Just run the chaser in far enough to clean the threads, and no farther, otherwise a pipe plug will no longer tighten up and do its job. Also, many here may not know that, once a Stude block is properly cleaned, none of us will live long enough to see it ever become even 10 percent as dirty as most of them are that have never been properly cleaned, or not cleaned since the 60s - 70s. I would not even consider removing that 3/8" plug between rebuilds, or even once per decade. Maybe once every 20 years.

As for that one 3/8" plug, considering the way the motor sits in the car, that hole is the lowest point of drain for the driver's side, but there's not a mate on the passenger side, so not really sure what the engineers' point was in putting it there in the first place.

As for draining "water" out of the water jackets before winter, does anyone really run water, or anything less than the proper concentration of coolant, year round? When we were young and dumb high schoolers, probably, but anyone nowadays? If so, what is your reasoning? I also would not even consider removing the "frost plugs" unless needed to clean a long overdue, filthy block. Each time removed and replaced the block hole loses a bit more surface. Then too, incompetent machinists often take it upon themselves to "clean up" those plug hole surfaces, which exacerbates the problem. One member posted here, a few years ago, of a plug blowing out shortly after putting his car on the road. That's why it's a good idea to carry an expander plug in each Stude, I prefer the ones with rubber in the middle, which are easiest to install, especially if roadside.

[M-Webb]

Thanks, to be clear, I'm not actually planning to remove the ones on mine. It was more of a thought than actual plan of action. The ones in my block look good and sealed to me, not planning to mess with them. Have way too many other things to fix on this motor, don't need to add unnecessary work.

My block has them on both sides, left and right. There is another one on my block on the right side near the full flow oil filter mount.

I just got the thread chasers to make sure all the threaded bolt holes in the block are as clean and clear as best as can be before I start putting things back together with torque specs., etc. Those, I'm going to leave as is. But good to know on the pipe threading vs. bolt threading difference, will keep that in mind in the future.

I took that one freeze plug out of my block that you can see in the photo because the shop that did those sunk that one in extra deep, more than the others. And I wasn't sure how much bite that one had left on it. So I took it out and am going to redo that one. I think I'll leave the others, think they should be good based on what I found on that one. It was pretty snug, but also looks like they put a little skim layer of JB Weld or similar on them too to help seal them up just in case.

[JoeHall]

M-Webb, oops, you are right, there's a 3/8" water jacket plug on both sides, I may have been confusing 259/289 with 352, but would not swear to it, and too lazy to go out and look. I once had a machinist crack a 289 block when removing one of those plugs. I did not notice it till initial run-in, after having reassembled the engine and put it back in the car. Since then, I always remove them myself, and always replace them with the external hex head type, as yours. I hate the ones with internal hex head, and have always believed that is how the machinist cracked the block. With those, when you insert a hex (Allen) socket and apply torque to unscrew, it expands the upper body of the plug slightly and makes it even harder to break loose.

Come to think of it, I believe on 352 (56J) motors, those plugs are 1/8", and one is on the rear but the other is mid-point of front and rear.

[bensherb]

I replaced those plugs with a valve and some copper tube. It makes changing a thermostat or water pump a MUCH cleaner job since you don't end up draining much of the block onto the floor. I've actually used them to drain the block several times,

[Jeffry Cassel]

FWIW I like a nice glob of Never Seize on it too!

[Colgate Studebaker]

Something my past machine shop always did when they installed freeze plugs was to put a thin layer of Permatex around the plugs outer perimeter and then install them. Never had a leaker in years and years of building engines. Bill

[JoeHall]

Something my past machine shop always did when they installed freeze plugs was to put a thin layer of Permatex around the plugs outer perimeter and then install them. Never had a leaker in years and years of building engines. Bill

I am a stickler for installing new plugs myself, and not allowing the machine shop to do it. The last 289, despite clearly telling the machinist to leave them out, they still took it upon themselves to install them, and used cheapo Mustang style plugs. Once I got the block home, I promptly removed them and installed my favorite brass, deep dish Dormans. Have never had one let go (knock wood). The 352 motor's freeze plugs are usually an even worse fiasco at machine shops, since the correct plug is 1-49/64" OD, but they always wanna install 1-3/4", again, despite me telling them to leave them out. My favorite coating is no. 2 Permatex, and I put a thin skin on the plug OD and on the wall of the block hole.

[Buzzard]

I have been installing drain cocks on my big block Oldsmobiles for years. I would never do it any other way as I have never had a problem.
Bill