Bigmouth passages
Thread Starter
Joined: Feb 2002
Posts: 3,462
Likes: 4
From: N. Illinois
Car: 92 GTA/ 00 TA
Engine: 383/350
Transmission: 700R4/T-56
Bigmouth passages
There are 3 ports on the front of the TPiS Bigmouth base. 1 gets a coolant nipple, 1 gets a coolant sensor, and the other gets plugged. Those of you that have the bigmouth base, what did you use to plug it? Size? Pitch?
Senior Member
Joined: May 2005
Posts: 777
Likes: 1
From: Windsor Ontario Canada
Car: 89 jaguar xjs convertable
Engine: 89 L98 5.7 TPI
Transmission: 700R4
Axle/Gears: 3.23 dana 44
Re: Bigmouth passages
Its a pipe thread....can't remember..either 3/8" or 1/2" pipe plug
Senior Member
Joined: Mar 2004
Posts: 923
Likes: 2
From: Bakersfield, CA
Car: 91 Z28
Engine: 383 SuperRam
Transmission: ProBuilt 700r4
Axle/Gears: G92 3.23
Re: Bigmouth passages
correct it is 9/16", but npt sizes are way different, you need a 3/8" NPT plug for that hole. most parts stores carry these, even hardware store for under a buck.
Thread Starter
Joined: Feb 2002
Posts: 3,462
Likes: 4
From: N. Illinois
Car: 92 GTA/ 00 TA
Engine: 383/350
Transmission: 700R4/T-56
Re: Bigmouth passages
I got a 3/8 npt plug today. Talk about tight. I can barely get the thing started. I wonder if my casting is bad. I had to grind a big of metal away from around the vacuum port just to get that nipple in.
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Supreme Member
Joined: Apr 2002
Posts: 1,119
Likes: 1
From: Armpit state
Car: 71 Nova
Engine: Superramed 383, Topline heads
Transmission: 700r4
Axle/Gears: 8.2 posi 3.08
Re: Bigmouth passages
It should go in just dont try to force it in all at once. Back it off a few times with some teflon and it should go in. It wouldnt hurt to run a tap through first.
Joined: Jul 1999
Posts: 10,950
Likes: 27
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: Bigmouth passages
I put my fan switch in that third hole, and extended the wires to it. That keeps it away from the headers and keeps the connector from getting brittle and breaking.
Then just plug the hole in the head.
Then just plug the hole in the head.
Supreme Member
Joined: Aug 2004
Posts: 1,214
Likes: 3
From: Norwich, CT
Car: '89 Trans AM/'88 GTA
Engine: (2) Tuned Port L98's
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