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  #1  
Old 03-21-2018, 08:45 PM
longranger's Avatar
longranger longranger is offline
 
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Location: 45G, Brighton, MI
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Default Cummins Spinner with James Cowl?

I'm planning on an IO-360-M1B (horizontal induction) on my tailwheel RV-7, and I like the looks and the apparent performance gains with the James cowl & plenum, so it looks like the "Extended Cowl for Forward Facing Injected Engines" is the right one. I'm planning on the Hartzell Blended Airfoil C2YR propeller, so it looks like I'll need a 2.5" prop extension as well.

I would also like to allow myself one piece of bling and go with the Cummins spinner. I've done a little research, and haven't run across anyone on VAF with that spinner and a James cowl on a RV-7. (I could find no posts containing both James and Cummins.) With the Cummins spinner using Vans backplate, I can't see where there would be any issue with the fit of the Cummins spinner vs Vans spinner, but I figure it can't hurt to ask.

I did run across a few posts where 2.25" extensions were mentioned, and at least one post where someone used a 2.625" extension. Should I just wait until I've fitted the cowl, then just order what I need, or is there is enough range in the fit of the cowl to just make it work with the 2.5? I'd really like to get this right the first time...
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Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on order

Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album

1955 Cessna 170B flying since 1982

'To get something you never had, you have to do something you never did.' -Unk.
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  #2  
Old 03-21-2018, 08:55 PM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Default

Quote:
Originally Posted by longranger View Post
SNIP

I did run across a few posts where 2.25" extensions were mentioned, and at least one post where someone used a 2.625" extension. Should I just wait until I've fitted the cowl, then just order what I need, or is there is enough range in the fit of the cowl to just make it work with the 2.5? I'd really like to get this right the first time...
The stock Van’s spinner or the Cummins spinner makes no difference. Both spinners fit based on the same Van’s back plate.

Do not fit the cowl until after you have decide on a prop extension, and mount the prop with it on. If you are using a Hartzell CS prop you might find someone with a used hub to use for cowl fit up - but make sure all the dimensions match.

Carl
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  #3  
Old 03-22-2018, 06:59 AM
BillL BillL is offline
 
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And , I might add, if you select the Hartzell Composite prop, it will hit the cowl at full pitch unless you plan ahead. I extended my nose on the cowl, but after all that work, would recommend investigation of the hartzell spinner with the extended hub. Then it clears. Like Carl said, recommend all parts on hand for the cowl fitting. I used air pressure to the prop to activate the pitch, easily controlled with a regulator.

I love that prop!!
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  #4  
Old 03-22-2018, 07:11 AM
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maniago maniago is offline
 
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Location: Bowie MD
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Obviously not an RV guy, but the front ends of both the RV and Mustang James cowls are pretty identical. And I used the specified by Cummins Vans spinner backplate and doubler. Read the james instructions (same for both birds) and you'll see a 2.5" ext is what they call for. I have a mooney C2Y prop. With a blended, I dont believe you need an extension, at least a M2 buddy of mine with the james did not. Calling James is the best way to "trust but verify". I did.

Purdy combination!
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MustangII (FoldingWing) "FirewallFwd&sundries": IO360B1E,RSA,C2YR-BF/F7666-2,Superior sump,James; 2xHXr,MiniX,EIS,480,327,240,SL30,Navworx; SteamAlt,AS,VSI
Don't be a hater; I'm a cousin with thin wings!
N251Y (res)
Dec2017

Last edited by maniago : 03-22-2018 at 07:17 AM.
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  #5  
Old 03-22-2018, 08:08 AM
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Bob Martin Bob Martin is offline
 
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Default James

I have done 2 Vans to James conversions on RV-6's.
2.25" extensions on both.
I was told or read to get 2.25 at the time, but the James literature now says 2.5"
Both my updates were extended cowl and carb versions. Extended sure looks the best in my opinion.
After doing mine, I would say, 2.25 works well, but up to 3" would also. Just consider W&B a little here. As said before, you install the prop and spinner and make the cowling fit to it. Shorter extension, trim more off cowl, longer extension and trim less. You will also be extending the engine plenum intakes to the back of the inlet rings so you will make that fit as well.
Both my installs were to Hartzell paddel prop, same fit as BA......
The WW 74HRT doesn't fit the James cowl without extending the prop projection out +/- .75".
-----------------------------------
From JamesAircraft.com

We offer three different cowl versions for the RV-6/7/9:

1) The standard length (shorty cowl : (34-5/8″ length) for carbureted or updraft fuel injected engines uses the same propeller/extension combinations as for standard Van’s cowling.
This cowling uses Van’s filtered air box.

2) The extended length: (37″) for carbureted or updraft fuel injected engines

3) The extended length: (37″) for forward facing fuel injected engines and updraft,
require either an extended “M” hub propeller (or equivalent), or the “CY2R”hub with a 2-1/2” extension.
For all fixed pitch metal or wooden propellers a4″ extension is required.

All cowl measurements are taken from the firewall to the prop spinner ring and include trim area.
-----------------------------
37" less 34 5/8" = 2 3/8....so you can see where the 2.25 or 2.5 comes from.
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RV-6, 0-360 Hartzell C/S, Tip up, 1150+TT
James extended cowl/plenum, induction, -8VS and Rudder. TSFlightline hoses. Oregon Aero leather seats.
D100-KMD150-660-TT ADI2- AS air/oil seperator. Vetterman exhaust with turndown tips.
Louisa, Virginia KLKU N94TB
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  #6  
Old 03-22-2018, 08:16 AM
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maniago maniago is offline
 
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Actually, pretty sure the 2.5" comes from the difference in hub length between the paddle prop and the blended prop......
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MustangII (FoldingWing) "FirewallFwd&sundries": IO360B1E,RSA,C2YR-BF/F7666-2,Superior sump,James; 2xHXr,MiniX,EIS,480,327,240,SL30,Navworx; SteamAlt,AS,VSI
Don't be a hater; I'm a cousin with thin wings!
N251Y (res)
Dec2017
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  #7  
Old 03-22-2018, 08:58 AM
Bob Martin's Avatar
Bob Martin Bob Martin is offline
 
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Quote:
Originally Posted by maniago View Post
Actually, pretty sure the 2.5" comes from the difference in hub length between the paddle prop and the blended prop......
Mani.......my cousin!
We may both be right.
Pretty sure there is a "model" of hub that would take up the 2.5"or so difference and that might be what Will James was shooting for with the extended version cowl.
But it also coinsides with the difference on cowl length.
I have always tried to stay away from odd or non standard parts, for ease of future upgrades that come way sooner than I expect.
One could swap a standard paddel prop for a Blended prop without changing anything.
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RV-6, 0-360 Hartzell C/S, Tip up, 1150+TT
James extended cowl/plenum, induction, -8VS and Rudder. TSFlightline hoses. Oregon Aero leather seats.
D100-KMD150-660-TT ADI2- AS air/oil seperator. Vetterman exhaust with turndown tips.
Louisa, Virginia KLKU N94TB
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  #8  
Old 03-22-2018, 09:20 AM
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longranger longranger is offline
 
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Quote:
Originally Posted by Carl Froehlich View Post
...

Do not fit the cowl until after you have decide on a prop extension, and mount the prop with it on. If you are using a Hartzell CS prop you might find someone with a used hub to use for cowl fit up - but make sure all the dimensions match.

Carl
Thanks Carl, that makes sense. How consistent are (I)O-360 cases? Ie., could a red tagged case and crank be be used with a prop hub to fit the cowl? I didn’t get this far on my HRII project when I lived near Bakersfield, but I remember that there was a 540 case with a PVC “crankshaft” and a plywood “backplate” floating around among builders for fitting cowls. I’d rather put the engine purchase off as long I can, but if it makes a difference in fitting the cowl, I’ll go ahead and get it.
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Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on order

Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album

1955 Cessna 170B flying since 1982

'To get something you never had, you have to do something you never did.' -Unk.
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  #9  
Old 03-22-2018, 09:30 AM
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longranger longranger is offline
 
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Quote:
Originally Posted by BillL View Post
And , I might add, if you select the Hartzell Composite prop, it will hit the cowl at full pitch unless you plan ahead. I extended my nose on the cowl, but after all that work, would recommend investigation of the hartzell spinner with the extended hub. Then it clears. Like Carl said, recommend all parts on hand for the cowl fitting. I used air pressure to the prop to activate the pitch, easily controlled with a regulator.

I love that prop!!
Thank you Bill, I’m pretty sure about going with the compact hub metal BA prop, but thanks for the heads up in case I change my mind! Also, thanks for the tip on activating the prop pitch. I’m positive that it wouldn’t have occurred to me to do it that way...
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Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on order

Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album

1955 Cessna 170B flying since 1982

'To get something you never had, you have to do something you never did.' -Unk.
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  #10  
Old 03-22-2018, 09:42 AM
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longranger longranger is offline
 
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Quote:
Originally Posted by maniago View Post
Obviously not an RV guy, but the front ends of both the RV and Mustang James cowls are pretty identical. And I used the specified by Cummins Vans spinner backplate and doubler. Read the james instructions (same for both birds) and you'll see a 2.5" ext is what they call for. I have a mooney C2Y prop. With a blended, I dont believe you need an extension, at least a M2 buddy of mine with the james did not. Calling James is the best way to "trust but verify". I did.

Purdy combination!
Thanks for photo Mani! If you hadn’t mentioned it, I wouldn’t have looked close enough to notice that it wasn’t a -6 or -7 slider. That IS a nice looking combination! It’s very clear on the James website that with their long cowl an extended hub (M-style) prop doesn’t require an extension, and that they recommend a 2.5” extension for the C2YR compact hub prop. From my research so far, the extended hub props are less common and can be more expensive, so I think I will opt for the compact hub with an extension. I will definitely talk to Will and/or Sam before buying.
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Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on order

Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album

1955 Cessna 170B flying since 1982

'To get something you never had, you have to do something you never did.' -Unk.

Last edited by longranger : 03-22-2018 at 10:03 AM.
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