Who uses petcocks on side of the block?

[70sixpkrt]

This is a stupid question but is it a good idea to use petcocks on the side of the block instead of a plug? What size petcocks are they? I want to clean the threads first so what size tap do I use?

[Mefirst]

The petcock has the same thread size as the one in your radiator. I have petcocks on both sides of my Hemi block..

/Tom

[70sixpkrt]

Do you know size tap I should use to ckean the threads?

[John_Kunkel]

The block drains are 1/4" NPT.

[70sixpkrt]

Thanks. I just bought a 1/4"x18 NPT tap and cleaned the threads. Put some teflon paste on the petcocks and installed them.

[histoy]

I put the petcock on the driver's side of my 440 block, but I couldn't use one on the passenger's side, because it was too close to the motor mount.