SJ cowl spacer

[JeremyL]

I am about to order an engine and propeller. I will be utilizing the sam James cowling. The engine is IO 360 M1B, the propeller is a sensenich 3 blade ground adjustable. My question in which I can’t seem to get answered is… will I need a spacer and if I do, what size spacer will I need? I’m hopeful that perhaps someone out there may know the answer to this or have this combination. The answer may be hidden in information that I am just not smart enough to dig up. If anyone has any insight, please do share. Thank you a whole ton in advanced.

 

[bonefishdave]

Yes, you will need a spacer. If memory serves me correct, it’s 2 and 1/4 inches but I’m not 100 percent sure.
Sabre makes the spacers, if you contact them I’m sure they will know which one you will need for the prop you are using
https://www.sabermfg.com/

 

[Webb]

When I converted my RV7 from Vans to James, a spacer was required.
It was greater than 2 but less than 3 inches from what I remember but I can’t recall the exact size.

 

[D Weisgerber]

I'm running a James cowl and I used a 2 1/4 inch spacer.

 

[agent4573]

Motors with horizontal induction will use the sam James long cowl and requires either a 2.25" spacer or an extended hub prop. Saber manufacturing is a good source for the spacers, and he'll need to know what size bolts you ordered on your motor and prop. I'm not sure if sensenich offers the extended hub like hartzell does, but you might want to call and see.

If you went with a vertical induction setup, you'll be using the same James short cowl and don't require a spacer.

 

[Capflyer]

Motors with horizontal induction will use the sam James long cowl and requires either a 2.25" spacer or an extended hub prop. Saber manufacturing is a good source for the spacers, and he'll need to know what size bolts you ordered on your motor and prop. I'm not sure if sensenich offers the extended hub like hartzell does, but you might want to call and see.

If you went with a vertical induction setup, you'll be using the same James short cowl and don't require a spacer.

This is correct. If you have not ordered your propeller yet and need the long cowl (horizontal forward facing induction), just order the Hartzel extended hub prop and you won't need the spacer. Hartzel knows which one you need or check the James Aircraft website. The cowl for vertical updraft induction is a different shape than the one for forward facing induction.

 

[Freemasm]

All of the previous replies make an assumption. The OP needs to determine the flange-backplate distance for the prop he is considering. Sure, it's probably close enough to the props the cowl was designed around but verification is still prudent.

@ JeremyL. None of our business/don't know your intended mission(s) but a CS prop will increase your build's value, IMO.

 

[JeremyL]

Thank you everyone. It seems that I will just order the 2.25 spacer that sensenich provides with the prop. I guess I will truly find out once I mount everything up and see if there is an issue. Crappy way to find out but thus is life.
Oh and yes, trust me, I’ve looked at the differences and heard arguments of CS v FP. The technology on FP now is not the same as it was many years ago. I also could care less about the value as I’m not building it for a return. So for me as of right now, I am going with the 3 blade Sensenich GA. With the M1B, a CS can be had down the road if needed.

Keep the insight coming as far as this combo mentioned it helps everyone.

 

[Bob Martin]

If your asking about the prop extension, then you have decided on the long cowl. The long cowl gives more room for the induction systems and plenum connections and adds good looks and nice lines to the front of the plane.
So the longer cowl needs an extension on the engine flange to reach the prop.
Now Hartzell makes an extended hub for this very reason, but if you are using a FP prop or a standard hub CS prop, you will need a hub extension.
The extension length is not set in stone, James Cowls said 2 1/4" but in reality it can a little different, like 2.5 or 2.75 etc because you actually install the cowl to the spinner back plate location and there is a trim-able area on the rear of the cowling to allow some give and take on the distance.
My opinion is 2 1/4 is minimum as you will want room when installing the induction system. But if you find a nice 2.5 extension, used....that would work as well....

If any doubts call James Aircraft--They make our RV's go faster!
512-429-0230 Jimmy Cox 512-429-8749

I met them at SNF this year and they are nice folks.....info above is from their business card.

 

[JDA_BTR]

Lots of threads about props and extensions. I went with a standard prop and an extension so that if there is ever a reason to replace or repair the prop it will be easier to source. Common parts are easier to find. I figure the spacer won’t ever fail but if it did my theory falls apart!

 

[jclark]

I am about to order an engine and propeller. I will be utilizing the sam James cowling. The engine is IO 360 M1B, the propeller is a sensenich 3 blade ground adjustable. My question in which I can’t seem to get answered is… will I need a spacer and if I do, what size spacer will I need? I’m hopeful that perhaps someone out there may know the answer to this or have this combination. The answer may be hidden in information that I am just not smart enough to dig up. If anyone has any insight, please do share. Thank you a whole ton in advanced.

There are a lot of responses based on the assumption that you have decided to get (or already have) the original Sam James "long cowl".

FYI:

Some years ago, I contracted with Will James (the son) to make the "shortie cowl" against my spec of "dimensionally consistent with the "standard Van's cowl".

The current owners of this business continue to supply that cowl as well (per my discussion with them at SnF). So, if you have not purchased a cowl yet, you may wish to have a dialog with them about the short version.

WARNING! The short version is by definition CLOSER to everything. Therefore the flexible couplings will require a more precise alignment of the circular inlets.

Also, I had to make a custom fiberglass part to make the transition from the round engine air inlet to the "D" shape of the Van's airbox.

I do NOT, have a financial interest in/gain anything from the sale of the "shortie", nor am I proposing it. I just want to share info based on some history that may not have been known.

 

[JeremyL]

Just wanted to answer a couple questions.
Yes I have decided to go with the long cowl and plenum. As well as the direct air inlet for the horizontal.
Yes I have called both sensenich and James aircraft and discussed ideas with them. I needed to get some information from sensenich to relay back to James aircraft. I have called James aircraft 4-5 times and left 3 messages over a week without a return call. So I’ll go with the 2.25 spacer and figure it out from there.

 

[Capflyer]

Now that we know it is horizontal induction with a FP prop, you will need the long cowl and a prop spacer. Does Sensenich make the three blade prop you want with an extended hub? If so it would alleviate needing the spacer.

Here is a chart for selecting the correct James cowl based on the variables.

 

[JeremyL]

Now that we know it is horizontal induction with a FP prop, you will need the long cowl and a prop spacer. Does Sensenich make the three blade prop you want with an extended hub? If so it would alleviate needing the spacer.

Here is a chart for selecting the correct James cowl based on the variables.

Thank you for making that chart (assuming you made it). Sensenich only has the hub they use for the blades . It’s a m8 they told me. Sensenich explained it doesn’t really have anything to do with the hub, it more has to do with the spinner back plate.