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View Full Version : Exhaust manifold drain plug plug thread size


Worthing skier
12-04-2011, 08:57 AM
Hi All

As per the tittle , I want to buy a tap to chase out the thread on both the 3/4 in manifold drains holes.
Does anyone know the correct thread pitch tap to buy .
This is on a 1993 Prostar 190 with a 285 hp inmar .

Many thanks


Kevin

CantRepeat
12-04-2011, 09:08 AM
Hi All

As per the tittle , I want to buy a tap to chase out the thread on both the 3/4 in manifold drains holes.
Does anyone know the correct thread pitch tap to buy .
This is on a 1993 Prostar 190 with a 285 hp inmar .

Many thanks


Kevin

Aren't they just NPT?

mikeg205
12-04-2011, 12:12 PM
Yes, that's correct Cantrepeat... at least that's the case on my 1995...all drains are NPT

Lumbergh
12-04-2011, 12:59 PM
3/4 NPT for the manifolds, 1/4 NPT for the block (shower / petcock).