Manifold pressure guage

[smcnutt]

My Pacer (0290-D2) has a manifold pressure guage in it. However, since we bought the plane it's never appeared to read correctly and it has now dropped to 11-12 and stays there. We've had no decrease in engine performance in any way.

My questions are:

Do I need a manifold pressure guage? In other words, should I bother to trouble-shoot it or simply pull it out of the panel? I have no immediate use for the empty hole in the panel[/*:m:hsit7lrs]
If the answer to that is "Keep it" then how do I trouble-shoot what's wrong with it. Somebody mentioned they can get oil in them and you need to clean it out and it will come right back to life.
[/*:m:hsit7lrs]
Also, if the answer is "keep it" then how do I use it? What should it read and what can I learn from it?[/*:m:hsit7lrs]

[JohnW]

Rip and tear. You don't need a MAP gauge unless you have a Constant Speed prop. It is of [very, very] little value in verifying carb ice, but if it's toast anyway then an EGT/CHT dual gauge is a MUCH better investment to put into the blank hole. Because there is such a premium in panel space in this Type, even a perfect MAP gauge is the first thing to go if you wanted to install, say... a VOR/LOC head (or ANYTHING else of any "value"). Don't forget to plug the tapping in number three cylinder when you yank it all out. There is more value in having the "fourth" primer nozzle than a MAP gauge, if you need another "excuse" to remove it. You can only find the "original" type primer nozzle if you have the Luck O' the Irish and HAPPEN to step on one at a Fly Market, but the new style (oh...1954 or so???) works just fine, even mixed with the "old" type.

If your MAP gauge filled up with oil, then the airplane was "maintained" by somebody with a relatively poor work ethic. There was a Piper S.B. the better part of a hundred years ago to add a .060" hole in the line where it comes out of the cylinder fitting. This eliminated the "oil in the MAP gauge" problem (in all fairness, it COULD HAVE been "plugged" with some spooge. But its moot).

[smcnutt]

JohnW, not that I don't appreciate your opinion (I do) but just seeing if their's any dissent. Anyone else see a reason to keep it installed? It had to be there for a reason back in 1953.

[Bultaco Jim]

I'd put a CHT in there, if you don't have one. Is there a chance the plane ever had a CS prop?

[smcnutt]

I'd put a CHT in there, if you don't have one. Is there a chance the plane ever had a CS prop?

Doubt it, but can't be positive. Don't see any reason we would put on on it in the future. Is their another use/function for a MP gauge?

[eskflyer]

I have a "53" Pa 22 135, converted to a real plane with the wheel on the right end and 150HP. It has the original MP gauge in it . It is coming out and a nice 4 position CHT is going in its place . The MP is useless unless running a conastant speed , supercharger , or you just want extra useless weight .

Just my opinion "not that its worth much "

3579A
John

[smcnutt]

I have a "53" Pa 22 135, converted to a real plane with the wheel on the right end and 150HP. It has the original MP gauge in it . It is coming out and a nice 4 position CHT is going in its place . The MP is useless unless running a conastant speed , supercharger , or you just want extra useless weight .

Just my opinion "not that its worth much "

3579A
John
Mine had the wheel moved to the right place as well but it still has the 135hp. I don't see a need to upgrade to the 150 until it's time for a new engine anyway. Hopefully, that will be way in the future.

If I were to put something into the panel to replace the MP I would probably lean towards a fuel flow gauge but CHT would be a close second. Which one did you buy and why?

"Opinion" is just what I was looking for.

[eskflyer]

http://www.boatersland.com/f210.html

Above is UHHHHHHHHH Approved lol. We have them in our kitfoxes and avids, and somewhere else . Very nice gauges and hardware.

CHT AND EGT from
http://www.westach.com/

Again have been runnning these in our planes for years . They do have TSO'D gauges . Can get them in just about any configuration you would want .

3579A
John

[smcnutt]

Seems like the concensus is that Piper put a completely useless instrument into the panel. That doesn't make a lot of sense.

[JohnW]

Seems like the concensus is that Piper put a completely useless instrument into the panel. That doesn't make a lot of sense.

No, that isn't true. Your reasoning is mis-applied. The Type Certificate for these airplanes includes the installation by logbook entry of a "Koppers Aeromatic, F200-H/00-74E". This inclusion of the MAP gauge was a "service" provided by Piper, since at that point in time, it was believed that MOST PEOPLE would put the Koppers on their airplanes (or at least TRY one at some point). And a lot of people DID try them. The Sensenich two-position prop was (I have it on good authority) a more viable prospect for improved performance (but it got a rep for shedding blades, one at a time), very good at what it did. But BOTH where EXPENSIVE to install and/or own. There was no other way to lean an engine in the early Fifties than by using the Tach or the MAP (doing it "by ear" is stupid AND expensive). Ice was noted, by a change in MAP at a given throttle setting. The market was mainly comprised of pilots returning from World War, used to sitting behind high output piston engines with manifold absolute pressure gauges. The instrument WAS NOT "completely useless", although "time" may make it seem [to some] as though it was. A lot has changed since these airplanes were first introduced. What may seem useless NOW was State of the Art, then. I don't LIKE the idea or inference that Piper was "senseless" or "cheap" (not that I am going to flip out over it...). On the contrary... these were good people, excellent at what they did, and not footloose or fancy-free with "unnecessary implementations" (however the Advertising Department did their damnedest to push what THEY thought was "progress" and where responsible for some pretty DUMB "progress". For example, the NOSEWHEEL, for people that were unwilling -or unable- to learn to be a decent aircraft operator).

[Hillbilly]

I was waiting on the aeromatic response, JohnW I Ka'nowed it was comin ;)

[smcnutt]

I was waiting on the aeromatic response, JohnW I Ka'nowed it was comin ;)

?????

[eskflyer]

I see the INFAMOUS AEROMATIC is still available for about $6000. lol . With used hubs . Dont think i will be flying one.


3579A
John

[smcnutt]

I was waiting on the aeromatic response, JohnW I Ka'nowed it was comin ;)

?????
OK, I'm with you. "Aeromatic" as in brand. I thought you were making some disparaging remark towards the nature of his response. :lol:

[JohnW]

What in the WORLD would ever make you think Hillbilly would make a disparaging remark??? :shock:

[Hillbilly]

What in the WORLD would ever make you think Hillbilly would make a disparaging remark??? :shock:

John, maybe he thought I was recommending aroma therapy...

No Sandy, I just knew there was a adjustable prop option and that it would not get past Professor Wilczak (spelling?)

[smcnutt]

Sometimes I'm just slow and or twisted. At first I thought your "aeromatic response" comment meant it was full of $#%@ and had an unpleasant odor. :lol: I guess I'm still stuck on your "Wanna Argue" thread on the other board.

However, I think I'm with you now. Please continue with your regularly scheduled conversation. :roll:

[Bultaco Jim]

Another example, of Johns line of thinking about how times change, is the mainly marketing decision of rushing to yokes instead of sticks back then. These days, I keep hearing how folks are trying to put sticks back in. Piper was just trying to stay competitive.
My 2 cents on which gauge to put in: CHT. Because, from everything that I have heard, fast temp changes in the head is one of the few ways to hurt these engines. I use it every time I decend, to stay under the 50 degrees per minute that Lyc recommends. The actual temp is less important.

[PeterL]

So, from what I understand, the M.P. gauge in my Pacer (290D2), is just taking up valuable space and not a required item. In fact for the past flights since I purchased the plane last June, I cann't remember if I really looked at this gauge in flight!!!!

I can certainly use this location for an E.I. Fuel Flow gauge I just purchased.

Peter Lubig

[Steve Pierce]

Much more useful instrument there Peter.

[Gilbert Pierce]

Peter,
That is exactly what is filling the hole my MP gage used to be in-the EI Fuel Flow Gage. Much more useful instrument.

[59pacer]

Just to wake up this thread again. If you are interested in how many BHP you're getting, then MP is needed. I'm interested when it's over 75%, because that determines use of leaning. In the past, I've used the Piper guide of '2400rpm at sea level plus 25rpm per 1000ft' as being 75%, and I normally cruise a tad under 75%. The new Leading Edge exhaust is giving more grunt, so I can't think of any way to establish 75% but to go to the PA22-160 Owners Handbook and look at the "Lycoming Aircraft Engine Performance Data' (very good reading glasses needed!) and run some numbers. In two weeks I'm off to 'the outback' for three weeks and about 30 hours of long straight legs, so I'm just about to pull the CHT/EGT gauge and install a MP gauge to look at the problem.
Any thoughts anyone, excepting whether I'll refit the CHT/EGT gauge when I get back?

[MN_flyer1]

Wouldn't it be nice to just install a Dynon and be done with it. Then you get all the tools. Those experimental guys get all the fun stuff.

Now back to our regular program.........

[dcflyer84]

I think I just found that panel space I've been looking for...

[Clayton Harper]

I think I'll put a MP transmitter on my Pacer. I have a JPI 730/830 engine instrument. With MP, the instrument will display percent HP. I have a 4 cylinder primer set up. I think that Piper used #4 cylinder primer port for the MP pick-up on the engine. My question "Is what size line did Piper run to the cockpit?"

[Homer Landreth]

I miss John W.

Wish it were 2009 again and we all hadn't got pissed off at each other.

[Clayton Harper]

Me too. ......(have to have 10 characters)

[wyandot jim]

Clayton,

Don't know what size line Piper used, but 1/4" works fine on #4 cyl.

[Curly]

and me! JW if you are still lurking - I often think of you (especially when weather events are close) and hope you are fit and well!

[Steve Pierce]

I have seen 3/8" lines used on the Tri-Pacer that looks original Piper.

[TriPacerPITT]

want to pull out my MP gauge, can some one tell me what size plug I need for the #3 cylinder?
J

[Steve Pierce]

1/8" MIP. Lycoming uses an Allen head plug.

[walt.buskey]

What Steve said… here's mine; taps at other cylinders have 1/8" copper primer lines.

1009410095

[smcnutt]

would that just be a logbook entry?

[dcflyer84]

When we removed my MP gauge, we just capped the line under the panel so if the next owner wants it back in, the line is already there.

[vas]

The Lycoming engine performance graphs in the PA-22 POH require manifold pressure, rpm, pressure alt, and OAT to compute engine performance at altitude. They also require a magnifying glass, a straight edge, time, and patience.

There is a very nice AirCraftPower app you can use in flight (if you haven't yet ripped out the mp gauge) for Apple iOS described at phiAeroApps.webs.com and available from the Apple AppsStore for free.

Vas

[andya]

I was able to find the true airspeed app on my iPnone, but not the engine power app.
Just the opposite for my iPad, found the engine app but cant find the airspeed app.