Best place to hook up boost/vacuum gauge

[Bruce Urie]

I'd like to ask you guys: where's the best place to hook up a boost/vacuum gauge? I'm thinking of ordering the AutoMeter 30in/30lb 2 1/8" gauge and putting it on the A-pillar. But after looking through a lot of threads here about the gauge, I still can't find out where to get accurate readings. One guy says remove the pipe plug, front lower part of intake manifold and replace it with a like plug for gauge...I get that, can't find this plug, another says pass side rear of intake manifold with T-fitting...very, very hard to get to,(I'm old, not Gumby ) then another place is unused port behind fuel pressure regulator, with direct signal to inake vacuum. I can't find that either. Jeeze, am I a dweeb or what? Would I get accurate vacuum and boost readings if I tapped into the line that my boost light on the instrument panel operates on? This is the passenger side, fender, and I think that sensor is the MAP sensor the boost light gauge works off of. I'd like to have both the light and the AutoMeter gauge work at the same time. I'm well aware of, thanks to you guys, that the factory boost light is notoriously inaccurate. So, any suggestions here guys, little help? My Grand National is mostly stock, with a few modifications. Would love to hook up an accurate boost/vacuum gauge see real boost in lbs and the vacuum for tuning. I sometimes feel like a real dweeb talking with all of you pros but even a dweeb has to have someone to turn to.
Thanks kindly.

Bruce '87 Grand National

 

[scottyb]

I tapped the stock gauge line between the coil pack/heater valve.

 

[gossamer]

Same here. Works like a champ and very easy to do. :smile:

 

[turbojd]

Same here, very easy to do.

 

[Bruce Urie]

That's a real good idea. Back behind the coil and heater valve where you can't see the splice. Great idea.
I'm thinking of replacing the plastic vacuum block on top of the plenium with Kirban's aluminum one (possible warpage) If I got the aluminum block with the extra port (Turbo Trans Am one), if I hooked the vacuum/boost gauge at this port, would I get just as accurate vacuum signal at this port? What do you think of this idea here? Just an idea. I'd like to have as accurate reading as possible.
And thank you for your help here. I appreciate it a lot.

Bruce '87 Grand National

 

[scottyb]

I wouldn't expect it to be any better, except that you remove the variable of possible leakage to the factory boost sensor.

Imo, that would look somewhat goofy as you would have to step down the hose size from that larger port meant for the brake booster.

 

[Blown&Injected]

Don't be so hard on yourself, I don't know about those tie-in areas either. Maybe you were reading some Hot-Air information???

I drilled and tapped the rear lower intake. Super clean, easy access, and no leaks there but I had the intake off when I did it.

 

[TURBOV8R]

Bruce,I could tell you where to hook it up on a Widebody Dash-9 or an SD40-2 road unit,but I betcha they are correct, and answered my same question!.D

 

[TurboMonte 2]

Any of the places you've described/ thought of will work just fine. The extra/larger port on the TTA alum billet block is for vac brakes hook-up & all others are same/count as GN. So, if you're not going to vac brakes, you could certainly use the additional/larger port as a vac/boost source...

 

[Bruce Urie]

Tubo/vacuum gauge hookup

Thanks to all who have replied with their expert opinions. I sure appreciate it. I have decided to go with Scotty, tubojd, gossamer, hooking it up in the line by the coil pack and heater valve. Great idea. :wink:
Joe, I know exactly what you're talking about, you train guy you, but those engines are a lot bigger, powerful and louder than my little V6
Blown&Injected, I never looked at it being hard on myself...maybe I was, but...I'm dealing with 21 year old engine/performance technology, and still trying to learn what makes these Grand Nationals tick. My late Dad had the 87 GN since new, always loaned it to me when I needed a car, but he refused to let me work on it at all. He had it all the time driving like a maniac racing anything with four wheels. I've been dealing with the small block Chevy engines all the time, with my '66 and '69 Vettes. That's the only up to date thing I had. (plus working on my brother's '71 Cuda 340 a lot) I can modify, repair, make fast, fix anything on those cars with no problem. They are fast, fun to drive, and understandable. But with the turbo Grand Nationals, I never had the chance to gain the knowledge of all my peers here on the forum. You all are really well experienced with these cars. I only got my chance to really know these GNs after my Dad just gave me his '87GN, but died soon after. Now, with me coming to terms with my grief, I'm going all out in understanding the operation of my '87 GN, thus the questions. I just love these turbo Buicks! I wouldn't part with my '87 GN for anything! I feel real stupid at times, but sometimes the only way to learn is to ask the experts like yourself. You even gave me the idea to tap into my oil fitting block to add an oil pressure line. I thank you for that, it worked great. I've never had my intake off so I had to look for a better idea for the boost gauge, seeing I didn't want to drill & tap with the intake on. So thank you to all. I appreciate it very much. You are all very knowledgable people. Take a bow!

Bruce '87 Grand National