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    Boost Gauge Fittings

Probably one of the worst things you can do to your Sy/Ty is install a boost gauge in either the MAP signal or the fuel pressure signal. Those two devices are very important to the proper operation of the ECM and the fuel system. If you install a mechanical boost gauge in one of those lines, that six feet of hose has to be pressurized before the MAP sees the true pressure in the system.

You're probably saying, "That makes sense, but where do I install a boost gauge, now?" There are a couple of places that will work, but I'm gonna show you how to plumb it into the vacuum source for the power brake booster.

Please pardon my non-expert photography skills...

As you can imagine, the line you are going to work on is the one running from the upper intake over to the power brake booster.

First, you need to remove that hose from the brass fitting that is screwed into the upper intake. If you have the stock setup, all you have to do is squeeze that hose clamp with a pair of pliers and wiggle that clamp down the hose. The hose should pull off that fitting after that.

Next, you need to remove that brass fitting from the upper intake manifold. Just use a wrench... it's a typical right-hand 3/8 pipe thread (NPT).

Here's where folks will differ in their install. The hole in the upper intake is a 3/8 NPT, and that hose barb is a 1/2... pretty common stuff... BUT there doesn't seem to be a small, one-piece fitting that'll give you a port for your boost gauge. Some folks are using a brass 'T' with a couple other fittings, but I wanted my setup to be smaller.

I found a fitting at a local hardware store that was 3/8 NPT male on one end and 3/8 NPT female on the other. That allowed me to use my original hose barb fitting for that brake booster hose. The wall was fairly thick, so I just bought a 1/8 NPT tap and made my own custom fitting.

I coated my hose fitting with pipe dope, and screwed it into the new fitting I found. I then stuck that in a vise and drilled and tapped a 1/8 NPT hole in the side. Most boost gauges use either rubber hose or small plastic tubing for their install, and most of 'em come with 1/8 NPT fittings.

Typical small hose fitting on 1/8 NPT fitting .

Typical compression assembly on 1/8 NPT fitting.

Next, you need to install that new fitting in the upper intake (with pipe dope or teflon tape, of course). You'll find it a lot easier to install if you don't already have the boost fitting screwed into the custom fitting.

Keep turning that fitting until the hole for the boost fitting is pointing toward the firwall. Now, put some pipe dope or teflon tape on the boost gauge fitting and screw it into the custom fitting... nice and snug. [see, I told you some of these photos weren't too good]

Now put it all back together and hook up your boost gauge. If you decide to sell the truck as completely stock, all you have to do is remove that custom fitting, and your boost gauge.

I found a very similar fitting in my latest Jeg's catalog. Part number 710-65310 is a 3/8 NPT male / 3/8 NPT female fitting with a 1/8 NPT hole tapped in the side ($10.99 in catalog 'V' - Sep '99). The only difference between that fitting and mine is that the Jeg's (actually Moroso) fitting is longer.

  • good - you won't have to install your stock hose barb fitting before you drill for the 1/8 NPT boost fitting... plus the hole is already there!
  • possibly bad - it will be more visible, due to its extra length... only an extra 1/2 inch... give or take

Now comes my sales pitch <grin>. If you want a really short adapter, but don't want to buy the 1/8 NPT tap, and/or you can't find that 3/8 male / 3/8 female fitting, I can build one for you. At first, I thought I would be able to beat the Jeg's price, but the cost is going to be similar to the Jeg's piece, because I have to supply a new 3/8 NPT male / 1/2 hose barb fitting. I forgot that the boost-tap hole is drilled through that hose-barb fitting as well.



3/8 NPT male / 3/8 NPT female fitting and
3/8 NPT male / 1/2 hose barb fitting
with 1/8 NPT hole for boost tap
1/8 NPT male / 1/8 tubing compression fitting $3.00
1/8 NPT male / 1/8 hose barb fitting $2.00

Prices DO NOT include shipping. So to save more money, you should order several <grin> US Postal Service Priority Mail is $3.20 for packages up to two pounds, so you can safely assume about $3.20 for shipping

Residents of TX please add 7.25% sales tax.  Residents of Garland, TX please add 8.25% sales tax.

Canadian residents please include an extra $3 per kit for the additional shipping costs. You'll need to send me a check made out in US funds and drawn on a US bank... or a Postal Money Order in US funds.

Make your check payable to "Ron Gregory" and mail it (along with ship-to address and part numbers) to:

Ron Gregory
2917 Snapdragon Court
Garland, TX 75040-2833

Then, send me some e-mail, so I'll know the check is coming.  That way I'll be looking for the check. As usual, I will send you e-mail confirmation upon receipt of your check.

(c) 1999 Auto Performance Engineering