Recommendations for pressure gauges for fuel setup

[shawnd]

My engine is on it's way back and my A&P and I are preparing for installation. For the fuel system setup, does anyone have recommendations for gauges that will comply with Continental's service directive SID97-3G and not break the bank? The preferred device "Model 20 ATM-C Porta-Test Unit" is hard to find and also ridiculously expensive! Hoping there's quality gauges that can suffice and meet the requirements. Would need a regular and a differential pressure gauge to measure the turbo fed intake system.

SID97-3G attached.

SID97-3G.pdf

[carusoam]

There isn’t anything more complex than setting up the fuel system of an M20K…

You might want to find the guy with the tools and the experience…. For the few hours it probably takes…

Rent the hired gun for that specific step…

PP thoughts only, from reading about engine set-ups around here…

Best regards,

-a-

[shawnd]

We are planning on having someone come up and fine tune and test the settings before I take flight. But I want to get it in somewhat reasonable shape or at least confirm that the repaired fuel pump settings are sane prior to ground run for leaks etc.  Chalk it up to wanting more knowledge about the dragons we so dearly fly with.

[N201MKTurbo]

I found calibrated gauges from Omega that were about $200 each. That’s about as cheap as you are going to get.

[shawnd]

Thanks @N201MKTurbo, those do look good. Unfortunately, their differential gauge is ~$1100 USD From scavenging online - found https://www.dwyer-inst.com/Product/Pressure/SinglePressure/Gages-Digital that seem to be in the reasonable bucket as well. Their differential gauges are ~$450: https://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gage-Switches-Digital/SeriesDH3.

 

[N201MKTurbo]

7 hours ago, shawnd said:

Thanks @N201MKTurbo, those do look good. Unfortunately, their differential gauge is ~$1100 USD From scavenging online - found https://www.dwyer-inst.com/Product/Pressure/SinglePressure/Gages-Digital that seem to be in the reasonable bucket as well. Their differential gauges are ~$450: https://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gage-Switches-Digital/SeriesDH3.

 

I was going to build up a setup for doing the Continental fuel adjustment. I needed it for a 310 (the one on my picture), but the owner decided to take it to the MSC so I still don't have a set of Continental pressure gauges.

[kortopates]

If and only IF you have calibrated fuel flow, you don’t need the differential gauge for setting up the metered fuel pressure. it’s better to use fuel flow directly to get the target FF at full power when you can. Then it’s less likely you’ll have to tweak it further . Then just use a single inlet pressure gauge to set the unmetered low Idle rpm pressure.

SID97-3 is obsolete, the reference/spec material is now in M-O Chapt 6 since 2017.


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[FloridaMan]

In case you're unaware, there are those fittings in the floor board on the copilot side that are there specifically so you can run hoses to the fittings and sit inside the airplane with the instrumentation. 

[kortopates]

i use a digital bluetooth enabled pressure transducer that i hook up and read from my phone on the cockpit.
actually enables flying it and reading it in the cockpit. But i have no need for that since installing a differential pressure transducer onto my EDM-900.


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[Fly Boomer]

1 hour ago, kortopates said:

SID97-3 is obsolete, the reference/spec material is now in M-O Chapt 6 since 2017.

Has the guidance changed?

[Fly Boomer]

26 minutes ago, kortopates said:

But i have no need for that since installing a differential pressure transducer onto my EDM-900.

This got my attention, but I can't find anything on the web connecting "differential pressure transducer" and JPI.  Can you say more about this?

[shawnd]

3 hours ago, kortopates said:

If and only IF you have calibrated fuel flow, you don’t need the differential gauge for setting up the metered fuel pressure. it’s better to use fuel flow directly to get the target FF at full power when you can.

This is a good point. I do have JPI EDM 830 which reads the nearly the same as the analog stock FF unit. They could be but doesn't mean they are calibrated as the k-factor could have just been entered from the factory unit. No mention of calibration in the logbooks either. But, to your point, for the ground run checks this should be sufficient till the proper checks are done.  I will report back what the pros use when they do the fuel setup.

[shawnd]

1 hour ago, Fly Boomer said:

Has the guidance changed?

Just took a peek at the M-0 manual - same instructions at a glance.

[kortopates]

2 hours ago, shawnd said:

This is a good point. I do have JPI EDM 830 which reads the nearly the same as the analog stock FF unit. They could be but doesn't mean they are calibrated as the k-factor could have just been entered from the factory unit. No mention of calibration in the logbooks either. But, to your point, for the ground run checks this should be sufficient till the proper checks are done.  I will report back what the pros use when they do the fuel setup.

Calibration is really a pilot action. Mechanic sets the K-factor from the transducer in the EDM. Then the pilot compares their fuel receipts against the reported Used over the course of burning about 100 gallons to adjust the K-factor further; per instructions in the EDM Pilot Guide.

[Guest]

On 3/28/2022 at 7:19 PM, shawnd said:

My engine is on it's way back and my A&P and I are preparing for installation. For the fuel system setup, does anyone have recommendations for gauges that will comply with Continental's service directive SID97-3G and not break the bank? The preferred device "Model 20 ATM-C Porta-Test Unit" is hard to find and also ridiculously expensive! Hoping there's quality gauges that can suffice and meet the requirements. Would need a regular and a differential pressure gauge to measure the turbo fed intake system.

SID97-3G attached.

SID97-3G.pdf 3.17 MB · 6 downloads

This might be helpful from the downloads section.  Unless your fuel flow and K factor is known to be accurate, I’d verify the high end fuel flow by checking metered nozzle pressure.

https://mooneyspace.com/files/file/138-continental-fuel-injection/

Clarence 

[shawnd]

That made my day @M20Doc! That's a must read for av geeks like me. Also went ahead and purchased the book at the very end of the PDF I can only imagine its filled with little pearls of wisdom for aircraft owners.

[A64Pilot]

As a Licensed Mechanic, if the factory manual requires calibrated instrumentation, then I believe it has to be within current calibration by a shop to NIST standards, and identified as such. I can’t quote chapt and verse on that, but when I was writing a repair station manual the FAA required that, including of course filing the certs.

Yes you can get FF meters very accurate by keeping track of fuel burned and changing the K factor to correct computed to actual and it best to track several fill ups and correct a big number, correcting 100 gls is more accurate than 10, but I doubt anyone could call that calibrated.

I agree with Carsten, this is important and not simple really, take the money your spending on gauges to pay for someone who does this frequently, and I’d ask to see the cal certs, often stickers on the back of the gauge, but will have an end date like milk does.

It’s often not done correctly, and in my opinion may have a lot to do with premature cylinder death on Conti’s.

By all means though correct your FF to be as accurate as possible and watch your FF at each takeoff, it will vary according to DA, but if it’s out of wack you’ll know to have it looked at. If nothing else if you accidentally attempt to take off leaned out, you’ll know immediately.

Edited March 30, 2022 by A64Pilot