Question on Fluidyne Radiator Drain Petcock thread Size?

[ERANJ]

Does anyone know the correct thread size for an aluminum Fluidyne radiator made around 2006 for CSX?

I have a 1/4-20 drain petcock and hose fitting as well but it will not thread properly. Is it possible its a metric thread 14mm 1.25 which I cannot find anywhere.

Any assistnace on the threads and where to purchase is appreciated.

Thanks,

[mickmate]

You should be good with 1/4 NPT. I find NPT (tapered) threads aren't cut very deep these days and I clean quite a few of them out with a tap so the fitting will go in.