Tap for block brass drain plug

[RonHens]

I have a 1983 MercCrusier 4-cylinder I/O with Serial# 6229776. I cannot re-insert the block brass drain plug and am wondering if someone can tell me the proper tap to use for that plug.

 

[solar7647]

Re: Tap for block brass drain plug

Had the same prob, I just took the plug to NAPA ( or any hardware/auto store) and use their handy dandy thread gauge that you can just screw it into to find the correct size. IT worked out to be the best way to find out, asking just got me a ton of diff answers.if memory serves correct it was like 1/4 pipe, but don't quote me.

 

[Bt Doctur]

Re: Tap for block brass drain plug

if its about a 1/4 inch in diameter its called 1/8th pipe tap. If its about a 1/2 inch ,its called 1/4 inch pipe tap.
These are "tapered threads" you DO NOT drive the tap in all the way