welch plug 21 stud engine.

[fftoddster]

I know the welch plug at the bottom of the block is 3/4". The trouble I am having is getting it to seal good because there is some corrosion in this area. I have tried sealant but think it is still weeping.

Does anyone know or have a block available to measure what the inside diameter of the bore is that the 3/4" welch plug goes up against?

I am thinking of trying to find a freeze plug that will fit up in there and then back it up with the 3/4" welch plug with sealant.

Is it 5/8" ? I do not and will not have access to it for several days and I would like to start hunting down a plug to fit it.

Thanks
Todd