318 coolant drain plugs

[nobananas]

Hi guys. Got a rebuilt 318 in a 67 Fury and have just realized it's missing the coolant block drain plugs from either side down by the sump line near the engine mounts. Anybody know what thread size they are ? I think they're are 1/8 NPT. Does this sound right ?

 

[MoPar~Man]

The only drain plugs I've handled lately (6 months ago) were the ones on my '01 Ram (Magnum 318). No idea what the threads were. Should be easy enough to get an assortment of short bolts from a hardware store and try them to see which ones fit.

Where did you get the rebuilt engine from? Is it an LA block?

 

[Big_John]

1/4-NPT, not 1/8

Double check me by measuring the internal diameter of the threads. For 1/8-NPT, it will be about 9 mm and about 11.2 mm for the 1/4- NPT. Those are approximate and the tapered threads won't really give you a good measurement, but it'll be close enough to double check. I used metric measurements because you're across the pond....

 

[413]

Pipe threads, use anti seize and don’t make them too tight. It is nice to remove them later to drain and flush the block as needed.

same size as a BB mopar also.

 

[nobananas]

1/4-NPT, not 1/8

Double check me by measuring the internal diameter of the threads. For 1/8-NPT, it will be about 9 mm and about 11.2 mm for the 1/4- NPT. Those are approximate and the tapered threads won't really give you a good measurement, but it'll be close enough to double check. I used metric measurements because you're across the pond....

Thanks, I guessed at 1/8 NPT as I found a seller who listed some at roughly 10mm which is around what I measured and close to what you have said at 9mm. I'll be honest, I really struggle with imperial measurements now so thanks for the metric conversion ! I'll double check tomorrow to be sure.