Petcock - Engine Block

[Richard Cope]

Going to be flushing my antifreeze and want to replace the petcock in the engine block, hasn't been opened in years.   Like to have one a new one on hand before starting.  Does anyone know the thread size, thinking that it is probably 1/4 NPT however not sure.  The engine is a stock 201 used in a 1939 Plymouth.

 

Many Thanks  Richard

[Plymouthy Adams]

if in doubt, pull it, carry it to your local parts house....they match you up easily.....the ones I have are 1/4 NPT

 

[dpollo]

the most common block drain is a simple butterfly handled valve available new at most any auto supply.   as PA says 1/4 pipe thread  9/16 wrench needed 

[Don Coatney]

10 hours ago, dpollo said:

the most common block drain is a simple butterfly handled valve available new at most any auto supply.   as PA says 1/4 pipe thread  9/16 wrench needed 

 

Same one I installed in this oil filter.

 

[Richard Cope]

Thank everyone for your replies, Evans antifreeze was put in the engine after being rebuilt many years ago, however less than 4,000 miles . Last summer Evans tested and indicated that it was till good,  however with the age want to give it a flush.