I've gotten lot's of good advice for hooking up my boost gauge. Unfortunately my 89 is way different from even the earlier 90s non-intercooled engines. The only plug I see under the manifold looks like the tranny drain plug which takes a 3/8" insert. I've also been told to take one of the bolts off the top of the manifold to use. The bolt i took out has no outer threads and has to be pushed in before tightning it. Can i tap this area? I'm starting to get a wee bit frustrated with this deal and am about to tap into my boost tube which i think may be the easiest way of all. Any suggestions who've done this on an 89 would be great.

 

On the manifold of my 89, there was a plug I removed on the side of the intake I believe and put a bushing in there to hook up to. Worked very well.

 

DieselDuse is right. Drivers side of head, on flat 5/8" vertical side of head about 6" from fuel boost line. Yes you can tap into the intake cover too. Worse comes to worse, Just hook up a small flex line to your vacuum after drilling and tapping to suck out any aluminum shavings. Or take off intake horn and grid heater and vacuum.

 

If it's the plug i think ur talking about, I'm drillin and tapping. That'd be the easiest way I think. I'm not gonna dismantle the bracket that's in the way then guess what size bushing I'll need because there's no way the one autometer supplied will fit in there. Thanks.

 

In my 89 there was a 1/8 NPT plug just under the horn into the intak manifold just behind the throttle bracket. The plug has a hex (allen head) in it. It is in the exact same spotas my 93, just hidden thats all. I just plugged right into it and drilled through the throttle bracket to let the tubing through.

Its not a tough install.. You don't have to tap the intake like alot of sites tell you. All cummins heads have that test port for boost hookup.

J-eh

 

where lildog is talkin is where I put it on my 91. the 'air horn' deal is in the way on an intercooled truck, but on an 89 with the air horn going the other way, I'd think that plug would be very visable. I never looked at dad's 90 to see if that plug exists on his tho. but on mine its straight down from the air horn on the side

 

The mechanic where I work showed me the top of the manifold version on later models, same style fitting just underneath on my 89. Now I just hope the fitting autometer gave me will fit (it looks a little small to me). If not, I'll hit the hardware store I guess.