Q - screw-in block core plug removal

[JonE]

so what about these extra holes, filled with solder or whatever, up that end at either side? Presumably they stopped adding those through cost savings, or do they just not get to "that bit" either?

[Austin in the Shed]

Would think the holes were to support or locate the water jacket core and maybe they came up with a better way.

[David Grear]

I remove the plugs by drilling a hole in the centre of the plug using drill bits increasing in size to 3/4 of an inch.
Then carefully cut out the remainder with a die grinder until the it falls out.
The thread is 1 1 /4 x 16 and a tap is available from Tracey Tools.
One of our members manufacture the new plugs in brass that are then sealed using Loc Tite 515.
The small brass plugs are also removed the same way and they are 3/8 Gas. 
New plugs available off the shelf.
This might seem to be unnecessary but I am in Australia and the temperature is currently 38 degrees Celcius.

[Tony Betts]

the two smaller holes either end.

after manufactureing new blocks i can 80% say they were there originally to remove a stiffening wire for the core in production.

the blocks were cast upside down, and this inner core floats in casting.

would imagine if there was a problem in casting, the wire would stick to the block and be hard to remove.

the latter block had two chaplets in the casting to stop the inner core from floating.

we used the two chaplet method for the new blocks.

tony

[Stuart Giles]

David, That's interesting information about the thread of the large screw in core plug -@ 1 1/4" x 16 TPI it's the same as the rear axle hub thread. It's also happens to be  identical to the now obsolete British Standard Conduit thread of that diameter-so, on a dusty shelf somewhere in an electrical supplies store, there will be some conduit blanking plugs which will screw straight into an early block

[Charles P]

The conduit thread is mentioned in one of the standard texts (SBG or perhaps Williams).
I looked for that dusty shelf and years ago even my local ironmongers, who could rustle up drawer full of BSF box spanners in all sizes, drew a blank. Easy enough to make one in brass though.
The few times that I've drilled and chipped one out it's not been to much advantage and I haven't had buckets of crud come out. Proper chemicals, administered before machining, is by far the best approach.

[Steve Jones]

They can be removed - here's one I did earlier from a scrap block using heat and some brute force. However, I only removed it to prove I could and I wouldn't bother normally agreeing with Charles that chemical cleaning is a better option and has less potential for damage.


  Core Plug.jpg (Size: 22.13 KB / Downloads: 214)

Thread is certainly 16tpi x 1 1/4"

Steve

[Reckless Rat]

My block has screw in core plugs and there is evidence on the one at the back nearest the bulkhead that in the past someone has tried to remove it, judging by the chisel marks and the missing bits, but they obviously failed in their endeavours. I've just left it alone since I bought the car.

[Colin Wilks]

David, That's interesting information about the thread of the large screw in core plug -@ 1 1/4" x 16 TPI it's the same as the rear axle hub thread. 

I'm hoping Stuart is wrong about the hub thread, otherwise I've just wasted my money on a 1 3/8" x 16 tpi die for the hub.

[Zetomagneto]

4 different people have said 1 and a 1/4” oops!