What thread is the rear oil pressure port on a Stage II 153 Block

[eop002]

I am trying to address a nagging oil leak on my Stage II 153 On-center block and believe I've traced it to a small leak coming from the oil pressure port located at the top rear of the block.

I am using a NPT plug with teflon tape as well as thread sealer but can see it blowing out from the threads after a few minutes on running the engine. I should not see that if the plug is the right thread right ?

Thinking I may not have the right plug thread.

Anyone know what type of thread that oil port is ?
Any thoughts on what I can do to seal the threads enough to withstand the typical oil pressures involved in the Stage motors ?

Thanks.
OP

 

[BlownV6]

I am trying to address a nagging oil leak on my Stage II 153 On-center block and believe I've traced it to a small leak coming from the oil pressure port located at the top rear of the block.

I am using a NPT plug with teflon tape as well as thread sealer but can see it blowing out from the threads after a few minutes on running the engine. I should not see that if the plug is the right thread right ?

Thinking I may not have the right plug thread.

Anyone know what type of thread that oil port is ?
Any thoughts on what I can do to seal the threads enough to withstand the typical oil pressures involved in the Stage motors ?

Thanks.
OP

The big one is 1/2" NPT and there should be a smaller one off to the side thats 1/8" NPT. Use teflon tape and redo the sealant on those fittings!!!
Check for crack at those fittings incase someone has tightened them up to much. Good luck Mike

 

[eop002]

Thanks Mike. I looks like the big one is the culprit. This helps.

Oscar

 

[odell4o8]

The big one is 1/2" NPT and there should be a smaller one off to the side thats 1/8" NPT. Use teflon tape and redo the sealant on those fittings!!!
Check for crack at those fittings incase someone has tightened them up to much. Good luck Mike

Mike. one of my used old usac blocks has a # 10 an thread in the rear
it takes a O-ring fitting,
even has # 10 an in one of the oil rails behind the flywheel,
really mixed up,
later oc,