Technical Y block question

Dumb question but most of my tools are 300 miles away, I live in base housing and cant really do a lot of work here. I was flushing the coolant on my 272 Y block and I should have known by the stack of washers under one of the bolts that something was up. It was mostly held together by Permatex and the bolt with the washers doesn't draw up tight. I don't have any thread gauges or pitch gauges here but it looks like 3/8" 16, can anybody verify before I head to the store and buy a tap and some new bolts and or helicoils? Thank you in advance.

I guess I should have mentioned I'm talking about the thermostat housing bolts. Way to proof read Mark.

 

5/16 18 is correct, but could easily have been over size tapped in the past.

 

Sweet, Thanks! I'm going to run out and get some 5/16 18 and 3/8 16 bolts, some Permatex, and some jb weld and let it eat until I swap a 4 barrel intake.

 

Maybe a stud and nut would work ?

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Drill size for 3/8-16 is 5/16ths, which make it pretty handy to repair a stripped 5/16-18 hole with 3/8-16. Good luck.