O2 310 HP STC Conversion Question(s)

[FlyingScot]

Greetings all - 

I am contemplating a 310 conversion for my O2 - I already have an appropriate top prop, so I am hoping this will be relatively straightforward - 

The one thing I am having trouble figuring out is simply where to get this done/who does these now - I have searched the site archives, and most of the postings are fairly old on the subject - and it isn't clear where the dust has settled on the STC of late. Can any MSC do the conversion now, since apparently Mooney owns the STC. Or is Bob Minnis still the best source? 

Anyone have this done recently? Any thoughts / suggestions / answers would be appreciated. 

Also...a trivial question - I don't have a 900-class engine monitor (yet) - just a 700 and the Moritz gauges - which I like (a sickness, I know ). However, the Moritz RPM gauge is "hardwired" to redline at 2500 - so does the whole cluster have to be replaced to complete the conversion? Is there a replacement?

Thanks in advance - Bob

[mike_elliott]

I believe any MSC can do this mod. It makes a new plane out of it!

[hypertech]

I did it last year.  Mooney has the STC and you buy it through the MSC.  It cost me about $5-6k for the STC and another $1500-2000 on the governor.  Oh, and about $30 for the oddly specified glue for the new data plate.  The price may very a little bit based on who you buy it from.  I also already had the right prop.  But when they opened up the governor to update the spring, it needed so many updates and there was a broken something or other, that I was better off replacing the governor.  So, it was a matter of a new governor, a fuel flow adjustment, a gauge adjustment, and a pile of expensive paper. 

I don't think you replace the cluster, I think you have to add a new tach but I don't have the paperwork here with me.  Its about a half inch thick.  Its clear most of the price is printing charges.  I had an EDM 900, so for me it was a trip back to JPI to update the tach and fuel flow redlines.  

[kortopates]

Since your primary RPM gauge can't be modified like a EDM-900, they'll simply add a new approved for primary RPM gauge. All the pre-waas G1000 Ovations had the same problem and they added this inexpensive yet very reliable EI R1 gauge https://www.aircraftspruce.com/catalog/inpages/ei-digitalgraphic1.php 

If your governor is still in good shape, the prop shop should be able to easily enough convert it for less than half the cost of an overhaul. But they won't know till they open it up on the bench. 

You'll also be getting a POH supplement, the AFMS for the 310 HP upgrade, to update your POH. 

[Niko182]

I did mine last year too.

It makes a pretty different beast out of a plane. On a cold day of 40 degrees C, me and 40 gallons of fuel, i saw a 600ft takeoff roll, and the vertical speed stuck at 2000ft per minute, so the climb was more than 2000ft per minute since thats the limit of the gauge. I had the moritz gauges too at the time, and recently switched them out for a jpi900, but at the time, i just installed an EI R1. If you want the paperwork, i'd recommend getting it from @AGL Aviation. Although i didnt actually meet them, or do any labor with them,  i bought it throught them since they were the only shop actually selling the stc at 4,995, vs lasar which had it marked up to like 8 grand. Lack of sales tax was a nice touch too. I had my govornor also replaced. Realistically whay this does is cutoff abour 40% of your takeoff roll, and improve your climb, but during climb after 1000ft agl, I pull back to 2500rpm anyway. If i had to do it again, i would 100%, but this STC improved my plane a lot more than it will an ovation.

[rgpilot]

I did my 2004 Ovation last year. $5,000 to MSC Daytona for the STC and had prop Gov OH. Replaced prop with 4 blade. Replaced Moritz gauges with JPI 900. I know the RPM gauge only goes to 2500 on the analog dial but I was told the digital part of the gauge is not limited to 2500.

Plane takes off like a rocket ship and reduced nose weight about 30 lbs from 3 blade Mccauley. Lands much better with much less nose up trim.

[Niko182]

Just now, rgpilot said:

I did my 2004 Ovation last year. $5,000 to MSC Daytona for the STC and had prop Gov OH. Replaced prop with 4 blade. Replaced Moritz gauges with JPI 900. I know the RPM gauge only goes to 2500 on the analog dial but I was told the digital part of the gauge is not limited to 2500.

Plane takes off like a rocket ship and reduced nose weight about 30 lbs from 3 blade Mccauley. Lands much better with much less nose up trim.

What do you get cruise wise and ff on the mt 4 blade?

[rgpilot]

With the MT 4 Blade cruise LOP at 9000 full throttle and 2550 RPM get ff at 13.1 and 180k.

[KLRDMD]

6 minutes ago, Niko182 said:

It makes a pretty different beast out of a plane. On a cold day of 40 degrees C, me and 40 gallons of fuel, i saw a 600ft takeoff roll, and the vertical speed stuck at 2000ft per minute . . .

If you call 40ºC a cold day, what do you consider a hot day ??? 

[Niko182]

58 minutes ago, KLRDMD said:

If you call 40ºF a cold day, what do you consider a hot day ??? 

Fixed it for me. Still not cold but about as cold as it gets in socal.

[FlyingScot]

Thank you to everyone for the info - this is very helpful and answers all of my questions - Bob

 

[wcb]

Damn... reading this thread makes me want one.  Someone tade me outright a 310 hp O for a turbo normalized 1976 F!!!!!!!!!!!!!!!!!!!

[MIm20c]

The Mortiz gauge will read the proper amount on the digital portion.  But you will still need a certified unit like the R1 mentioned above. All the work can be done by a local shop you just need to call a MSC to send over the paperwork and send out the governor for a new spring. 

Before you pick a shop to do the work make sure they are willing to set the fuel flow above spec. You absolutely need additional FF for hot weather operation and many MSC shops are not willing. 

[FlyingScot]

1 hour ago, MIm20c said:

The Mortiz gauge will read the proper amount on the digital portion.  But you will still need a certified unit like the R1 mentioned above. All the work can be done by a local shop you just need to call a MSC to send over the paperwork and send out the governor for a new spring. 

Before you pick a shop to do the work make sure they are willing to set the fuel flow above spec. You absolutely need additional FF for hot weather operation and many MSC shops are not willing. 

This is great info - thank you. I am surprised -  Isn’t an increased FF spec part of the mod? If it isn’t,  to what should it be set to ensure correct op in all conditions? Thanks - Bob

[kmyfm20s]

1 hour ago, FlyingScot said:

This is great info - thank you. I am surprised -  Isn’t an increased FF spec part of the mod? If it isn’t,  to what should it be set to ensure correct op in all conditions? Thanks - Bob

Yes, stc increases FF to 27.2 gph at sea level. I keep mine at 29.2 but would not go less than 28.6 myself. 

[ilovecornfields]

Increased FF is part of the STC (essentially it is set from IO-550-G specs to IO-550-N specs.) Despite it being part of the STC many shops will set it too low. I had it done by a famous MSC who set it too low and almost cooked my engine. I had to take it to a less famous MSC to get it fixed. You should have 29-30 gph at 2700 RPM WOT on a standard day. That tightly cowled engine heats up quickly if the FF is too low.

[carusoam]

+1 on the 310hp STC...

+1 on Having the redline on the tach updated...

+1 on already having the Acclaim prop... that’s the expensive part...

+1 on getting somebody to raise the FF a couple of gph... the STC says 27.2 gph max...

Other places have less official docs that describe this change...

+1 on purchasing the STC from Mooney, as they are the owner of record...

 

Inviting @StevenL.... (Steven knows these details really well, and often gives experience)

My internet isn’t inviting people today...

Best regards,

-a-

[kmyfm20s]

Many shops will not adjust FF to the desired level because the STC specifies 27.2 gph. That puts you right at maximum performance mixture at 50 degrees ROP which makes for some really hot cylinders. The funny thing is the factory O3’s POH shows the FF redline at 30 gph so shops are ok if you asked for them to bump those up higher. The hanger fairies say it’s pretty easy to adjust FF with the right size Allen wrench and 1/4 turn at a time until proper FF is achieved. Rumors has it it takes about 1 1/2 turns to get it to 29.2  Gph . After 29.2 gph they found you get some engine stumbling when you go full rich on landing. I don’t usually go full rich on landing but if I needed to do a go around I don’t want the potential of the  engine stumbling or stalling. If I need extra cooling on takeoff which I do at times in the heat of the summer the low boost pump gives me the little extra I need. A properly calibrated FF gauge and engine monitor is essential.

[Chris K]

On 7/21/2019 at 12:23 AM, kmyfm20s said:

Many shops will not adjust FF to the desired level because the STC specifies 27.2 gph. That puts you right at maximum performance mixture at 50 degrees ROP which makes for some really hot cylinders. The funny thing is the factory O3’s POH shows the FF redline at 30 gph so shops are ok if you asked for them to bump those up higher. The hanger fairies say it’s pretty easy to adjust FF with the right size Allen wrench and 1/4 turn at a time until proper FF is achieved. Rumors has it it takes about 1 1/2 turns to get it to 29.2  Gph . After 29.2 gph they found you get some engine stumbling when you go full rich on landing. I don’t usually go full rich on landing but if I needed to do a go around I don’t want the potential of the  engine stumbling or stalling. If I need extra cooling on takeoff which I do at times in the heat of the summer the low boost pump gives me the little extra I need. A properly calibrated FF gauge and engine monitor is essential.

Could the fairies provide a photo of where that adjustment screw is located?

[Niko182]

1 minute ago, Chris K said:

Could the fairies provide a photo of where that adjustment screw is located?

Id like to know, for research purposes too.

[dflyp]

[hypertech]

That's a gauge adjustment.  The fuel flow adjustment is described in the service manual.  Its on the fuel pump kind of behind the oil filter.  I've had mine adjusted a couple times and the whole fuel flow setup done per the SB too.  My idle is still too high and I think I still need more fuel flow on the top end to keep the temps down on climb out.

What do others have their idle set at?  After I had the MSC do the whole fuel flow setup, my idle is a bit better but I'm getting about 830 rpm for idle.  Savvy says this is too high.  But I also don't want it to stall on me on roll out.  

[kmyfm20s]

Allen head inside orifice. They say the safety wire stays in place and need to shorten the Allen wrench.

FYI...This is only to only be done by your mechanic. This is just so you know where they would adjust it. 

Edited July 24, 2019 by kmyfm20s

[dflyp]

Oops, got two different threads mixed up in my head.

[kortopates]

That's a gauge adjustment.  The fuel flow adjustment is described in the service manual.  Its on the fuel pump kind of behind the oil filter.  I've had mine adjusted a couple times and the whole fuel flow setup done per the SB too.  My idle is still too high and I think I still need more fuel flow on the top end to keep the temps down on climb out.

What do others have their idle set at?  After I had the MSC do the whole fuel flow setup, my idle is a bit better but I'm getting about 830 rpm for idle.  Savvy says this is too high.  But I also don't want it to stall on me on roll out.  

TCM specs an Idle speed of 600 RPM for big bore 550's. With proper idle mixture and unmetered fuel pressure adjustments it should idle fine at that.

Higher max FF shouldn't prevent smooth idle, but adjusting the max FF setting can throw off the idle setting. TCM advises if you change one you must check the other and keep iterating till both are to spec.

 

 

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