Thanks for the TIP...USEFULL!

Do you have some experience in the fuel system for the TCM TSIO-360LB?

some experience: Unlike other IO-360 engines your waste gate is not normalized which is to say that at sea level you are permitted 10" of boost. You are permitted a maximum TIT of 1650 degrees. You are fuel injected therefore with a balanced set of injectors you can run lean of peak without engine roughness. Shorter stroke means your mag timing is -20 degrees. You can maintain your full rated 210 horsepower all the way up to your service ceiling but cylinder life will be shorter than a normally aspirated version of the same engine. The turbine bearings will degrade over time due to harmonic wear affecting the efficiency eventually requiring replacement. Any specific questions?

This is very helpful information.  On some engines that tend to run hot, such as the TCM TSIO 360GB, it is very import to know the actual MAP.  It would be very easy to continually overboost the engine (and further shorten cylinder life) based on bad MAP information.

Turn your altemeter to read sea level ( 0 feet elevation no matter what your current elevation is). Then read barometric pressure in the kollsman window. This is what your MAP gauge should indicate at your current elevation without the engine running.

This is a great method; I have not tried it yet bit I will! If it works and I have no dobt then it is the simplest possible method!

so if it is off how do you adjust the manifold pressure gage?  I am not looking for "send it out".  Is there a screw somewhere and where is it to adjust it?  Have you ever taken one apart?

It has been a long time since I have had one open on a bench and as I remember there is a simple screw referred to as offset (Zeroing) span is set by bending a link but the instrument case must be opened.

I tried setting the altimeter to zero altitude but at my field elevation the Kolsman window goes out if range. As near as I can tell that method is only good to  field elevations up to 1800 feet.

I am at 50 ft. so that is a possibility, Do you say the screw bends the link, and does it carry through the whole range?

and yes I know that is instrument shop work.

The bendable link sets the span which is the range between the lowest indication and the highest one. The screw sets the current position of the needle which would be called the zero except the gague does not have a true zero but indicates the pressure at the input port above absolute zero (average 29.92 at sea level).

I think you said the needle zero will move and weather or not my gage is good it will show the correct MP.  I plan on checking it with a mercury manometer over  the standard range aprox 14-31, and its for a homebuilt.

I do not know the rules for homebuilt aircraft but I know they are a lot laxer. Checking the range with a manometer is exactly what we would do in an instrument shop an it has been my experience that the span usually remains the same. The usual culprit in the offset is metalurgical changes in the bellows.

I just had my 231 stock mp gauge repaired.  There was a lot of brown/ black dust that came out of the instrument when I removed the hose.  My instrument shop soaked it for a week in a solvent and adjusted it.  Cost a whole $ 50.

I would say $50 is a real bargain and well worth it. One thing to remember is that the instrument is plumbed to the manifold and the instrument breathes with changes in pressure. In carburated aircraft that means that fuel residue can accumulate in the lines and instrument. Fuel injected aircraft are more imune but the air cleaner doesn't take out everything and carburator heat bypasses the filter. Rubber lines degrade and shed contaminents and if possible should be replaced with silicone.

Could you post the name and location of that $50 shop, that is a price I Like if all it needs is zero adjustment.