The International Cessna^® 170 Association

OK, it's getting closer all the time.

Looking at the pictures of the panel, it looks like there is a MP gauge.

Why? The airplane does not have a variable pitch prop, so why would it have a MP gauge?

check here for past discussions.

http://cessna170.org/phpBB2/viewtopic.p ... fold+gauge

Iceman07 wrote:OK, it's getting closer all the time.

Looking at the pictures of the panel, it looks like there is a MP gauge.

Why? The airplane does not have a variable pitch prop, so why would it have a MP gauge?

When I put the STS manifold vacuum system in my airplane, I also inistalled a manifold pressure gauge so I could get an idea of how much manfold vacuum I'd have at a particular throttle setting.

Regardless of whether I'm using the manifold vacuum system, it's a very useful instrument. More than once, cruising in cool damp conditions, I've notice small drops in manifold pressure (1/4 to 1/2 inch) indicating carb ice before there was an appreciable drop in RPM (especially on my old tach) or even a noticable change in engine sound, due to how slow it can change.

I also use it to set power for descent. Without changing trim, I can just pull off about an inch of manifold pressure for every 100 fpm decent I want. I can also hold that MP, gradually closing the throttle as the airplane descents. It's much more sensitive than the tach for this.

I now MP gauges aren't necessary, but I find mine very useful.

Miles

I'm with you Miles. I use my MP more that the tach. In fact the only thing I use my tach for is the mag drop and to make sure I'm not exceding red line.

I should mention that I, like Miles, have a fix pitch prop