[Johnny406]

Okay, I'm a bit of a doof and was uh, er, misreading my gauge. I have the combination vac/boost gauge hooked up below the carb on my TKII intake. I mistook my 7-12Hg of vacuum as boost. I see that if I rev up the motor (no load) my vacuum will slowly drop but I never see the gauge going into the boost.

I will run the other boost gauge to the hat today for comparrison but am I missing something here?

[twov8sandat4]

You need some sort of a load to see boost, either in gear, or stutterbox. AFAIK, freeload revving does not produce boost

[Johnny406]

I hooked the second gauge to the hat. It started making 1-2Hg at about 3000 no load while vacuum under the carb seemed to stabalize at 12Hg. This is with the XE274 cam and stock 96 heads.

[tininjun67]

that's normal, the butterflies are hardly cracked in order to free rev to 3krpm, so manifold vacuum will be what you're seeing. An old timer once told me "go drive the car". What he meant was, go drive the car, dumbass,(meaning I was the dumbass) let it tell you the whole story. I do this every time a weird problem shows up, or something I can't reproduce in the stall happens, or what I thought would fix it, in fact didn't. strap a video camera to the car somewhere and aim it at your gauges-tach, boost, fuel press. Then you can focus on driving and not your gauges. not much data can be collected during a free rev.

[Johnny406]

Originally Posted by tininjun67

that's normal, the butterflies are hardly cracked in order to free rev to 3krpm, so manifold vacuum will be what you're seeing. An old timer once told me "go drive the car". What he meant was, go drive the car, dumbass,(meaning I was the dumbass) let it tell you the whole story. I do this every time a weird problem shows up, or something I can't reproduce in the stall happens, or what I thought would fix it, in fact didn't. strap a video camera to the car somewhere and aim it at your gauges-tach, boost, fuel press. Then you can focus on driving and not your gauges. not much data can be collected during a free rev.

How true. I will finish wiring up the a/f meter then will take her for a little spin. Soon after, I'll trailer it down for a trip on a chassis dyno.

[tininjun67]

a trip to the chassis dyno will be money well spent at this point, it will help pinpoint fatal tune-up flaws before they have their way with an engine. be sure to have enough fuel system in the car before you get to that point.