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PA-12 O-235-C upgrade to 0-320

T

tbone

Registered User
Twin Cities, MN KANE
I am looking for good direction and suggestions on the upgrade from a 0-235-C to a O-320 I have some options on specific model of 320 to upgrade to.
What is the difference between the conical and dynamical mount?
Does it make sense to avoid buying a new mount if I can find an engine that comes with a mount? How much would I save.
Who has the STC for the upgrade?
Does a conical mount for a 0-235 work for an O-320?

Any help would be greatly appreciated!
 
The McKensie STC lets you use the 0-235 engine mount if you double the bottom tubes (easily done), lots of discussion on this site somewhere with nose heavy issues if you do that but I have never found it to be the case. Any you don't have to change any of the cowling. Now adding an 0-360 is another nose heavy discussion.

Search Type certificate A-780 here for STC owner info: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/MainFrame?OpenFrameSet
 
The best way is to do the short mount. It ends up a better airplane with a better cg.

I went with the crosswinds and the 160hp O-320.
 
PIPER J5.5 said:
The best way is to do the short mount. It ends up a better airplane with a better cg.

I went with the crosswinds and the 160hp O-320.
Click to expand...

What type of mount is the "short mount"?
Did you buy the STC and do the work yourself or have someone do all of the work?

Any idea on the cost?
What prop did you go with and what cruise speed does that yield?


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I have the Kenmore installation which uses a reinforced original mount. If you go as light as possible with accessories you can keep a happy CG and work on the back of the engine / mags. without swinging the mount. In my case I have a Niagara alum. oil cooler, Skytek starter, and a B&C rear mount alternator (20a). All these add up to around 18 lb. being removed from various stations north of the firewall. A Catto prop would take another 15 lb. off the nose at a very useful arm length but this is just a theoretical discussion, since they're not "approved" (insert rolling eyes emoji here). If a guy were to incorporate all those things together he could end up with a long mount 320 that CG's in the high 13's and flies solo with the H.stab nearly centered, but thats just speculation of course. I still think about going to a short mount when it's engine time but I'll cross that bridge when I reach it.
 
PerryB said:
I have the Kenmore installation which uses a reinforced original mount. If you go as light as possible with accessories you can keep a happy CG and work on the back of the engine / mags. without swinging the mount. In my case I have a Niagara alum. oil cooler, Skytek starter, and a B&C rear mount alternator (20a). All these add up to around 18 lb. being removed from various stations north of the firewall. A Catto prop would take another 15 lb. off the nose at a very useful arm length but this is just a theoretical discussion, since they're not "approved" (insert rolling eyes emoji here). If a guy were to incorporate all those things together he could end up with a long mount 320 that CG's in the high 13's and flies solo with the H.stab nearly centered, but thats just speculation of course. I still think about going to a short mount when it's engine time but I'll cross that bridge when I reach it.
Click to expand...

Sounds like you have a great setup. What type of exhaust do you have? Bring up north heat will be a priority to keep in the air during the cold months.
Any pictures of your engine/components would be greatly appreciated!

I agree on the catto prop. Would be an amazing drop in weight and at the best possible arm possible!
I am thinking cruise prop just because Ill be doing a lot of trips over 1hr. What do you run/achieve performance wise?


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tbone said:
Sounds like you have a great setup. What type of exhaust do you have? Bring up north heat will be a priority to keep in the air during the cold months.
Any pictures of your engine/components would be greatly appreciated!

I agree on the catto prop. Would be an amazing drop in weight and at the best possible arm possible!
I am thinking cruise prop just because Ill be doing a lot of trips over 1hr. What do you run/achieve performance wise?


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Click to expand...
I sent you a PM with some particulars but forgot cruise speeds. With either prop discussed in the PM I get about 90 @ 2400 and 95 @ 2450.
 
Pretty good speeds. What model 320 are you running? I understand there are some that are better than others.


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Looks like Most of your question have been answered here, FYI I have both a short mount and original conical mounts for sale, both new, for $500 each, Univair want almost a thousand dollars for there's,mine are factory originals with pic tags!
 
I used the Kenmore STC and kept my long mount. It’s a O-320A1A. Exhaust was changed to a PA22 style x-over. Kept my old muffler. Front oil cooler added. Only bite there is don’t have clearance for a light weight starter as the solenoid won’t clear. Solved the poor starter torque issue by switching to a Concord AGM 35A battery. Huge improvement over the G-35s, and only now showing signs of age after about 8yrs in service.
I recommend keeping the battery mount aft of cabin as that helps w CG too.
I cruise at a power that give
me the 80-85kts that I had w/ the O-235 and fuel burn is about 6.5gph.
You do need to change the horiz stab/elev out to bigger PA-18 style. Highly recommend putting VG kit on too as it almost eliminate need to retrim w power changes when flying slow.
Mikey


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Front oil cooler added. Only bite there is don’t have clearance for a light weight starter as the solenoid won’t clear. [/QUOTE]

You have to modify the oil cooler bracket.
 
PerryB said:
Front oil cooler added. Only bite there is don’t have clearance for a light weight starter as the solenoid won’t clear.
Click to expand...

You have to modify the oil cooler bracket.[/QUOTE]

Thanks.
Now that I think on it, I think my clearance problem is actually the InterAv alternator conversion I have.



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I agree on the catto prop. Would be an amazing drop in weight and at the best possible arm possible!
I am thinking cruise prop just because Ill be doing a lot of trips over 1hr. What do you run/achieve performance wise?

O-320A-- Sensenich 76-56 cruise prop. 26" Goodyears. On a hot day at 2400 I can cruise at 115 MPH. On a very cold day--- at 2300 It will cruise at 117 MPH. I keep the plane clean and more often than not it is waxed as well. Air speed indicator matches up closely with GPS speed.

I have the Kenmore long mount. It does move the CG up a tad. It's certainly different flying than an 18 w/ same engine and short mount.
 
Seaworthy said:

I agree on the catto prop. Would be an amazing drop in weight and at the best possible arm possible!
I am thinking cruise prop just because Ill be doing a lot of trips over 1hr. What do you run/achieve performance wise?

O-320A-- Sensenich 76-56 cruise prop. 26" Goodyears. On a hot day at 2400 I can cruise at 115 MPH. On a very cold day--- at 2300 It will cruise at 117 MPH. I keep the plane clean and more often than not it is waxed as well. Air speed indicator matches up closely with GPS speed.

I have the Kenmore long mount. It does move the CG up a tad. It's certainly different flying than an 18 w/ same engine and short mount.
Click to expand...

Seaworthy,
Those are some impressive numbers! Especially with 26" goodyears.

I'd be crazy if I didn't ask for pictures of your engine bay! Anything will help as I am going to start buying parts/accessories I'd like to see what fits in well and where.

Thank you for your great input.


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Here's a couple of shots of my 12 with a niagra oil cooler, Skytec lightweight starter and the B&C lightweight alternator (although the alternator only saved 1# over the original generator). I also have an Odyssey battery under the rear seat. With this set up, empty I have the trim way nose down. I love all the space in the engine compartment with the 18 exhaust.

IMG_3967.JPGIMG_3968.JPG
 

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MT12 said:
The McKensie STC lets you use the 0-235 engine mount if you double the bottom tubes (easily done), lots of discussion on this site somewhere with nose heavy issues if you do that but I have never found it to be the case. Any you don't have to change any of the cowling. Now adding an 0-360 is another nose heavy discussion.

Search Type certificate A-780 here for STC owner info: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/MainFrame?OpenFrameSet
Click to expand...


After flipping through the all of the STCs listed I am wondering if my opportunity to buy a O-320-D3G will work with any of them.
Many of the STCs list the O-320 but no specific model. Does this mean that the variant doesn't matter so long as the correct mount is used?


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Does anybody currently use a dynafocal mount? I'm looking for feedback on how CG is with O-320-D3G installed in PA-12.


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Anyone have a spinner and plate for an O-320 for sale or have a suggestion on where/what to buy? I am putting a border prop on and the old spinner won't work.


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