1954 freeze plugs size

[PHIL WHYTE CLC 14192]

Hello,
Does anyone know the actual size of the freeze plugs on the 54 engine - I only want to know about the ones in the water jacket ie the 6 in the block and the 4 in the heads - believe these are the same size. Before anyone suggests it - my blaock is away in the machine shop at the moment , so I can't measure them !
Thanks,
Phil

[John Washburn CLC 1067 Sadly deceased.]

Phil,

1 31/64"

john washburn

[PHIL WHYTE CLC 14192]

Thanks John, what an odd size to use , I wonder why GM chose that agianst 1 1/2 ? Phil

[Jay Friedman]

Several years ago one of the 1 31/64" freeze plugs in my '49 popped out because I had not installed it well following a rebuild.  At the time I couldn't find any replacements, so not knowing what else to do I bought a rubber 1½" freeze plug, the kind with the bolt in the middle that tightens the rubber against the block.  I lightly ground it down by rotating it lightly against my grinding wheel until I could push it in, then tightened the bolt and to my pleasant surprise it held water.  In fact, it has been in place for years without any problem.  Ironically, some months later I found a kit of 1 31/64" freeze plugs for a 331 motor so now have a plentiful supply. 

[PHIL WHYTE CLC 14192]

Thanks Jay,
I got mine , in brass from Rock Auto, made by Dorman, part number 560021. In the past , as I live in the UK and this size has never been available over here to my knowledge, I have got an 1 1/2 one and filed it down until it fitted - the last one I did like this leaked though ! So I'm glad I've now got the right ones.
Phil