Require More Room between Prop and Cowl

Mark C. · #1 01-10-2016, 12:00 AM

When the prop is still to close within 1/8" to the cowling, what options do I have for more seperation? Present set up IO 360 Catto Prop. Using Vans recommendations DWG C4. 2.25 prop extension, rear spinner, Catto Prop, spacer plate, front plate, crush plate, 8 bolts. RV9A. Thanks, Mark C. N119RV

jay.pearlman · #2 01-10-2016, 12:22 AM

Put an eighth inch washer between the engine mount and the firewall at all bolt locations (6?). It will move the engine forward. The challenge is whether the cowl can tolerate that.

petehowell · #3 01-10-2016, 12:34 AM

Hi Mark,

Do you have some pics you could post? Do you have the ability to take a bit off the back off the back of the cowl to slide the front away from the prop?

My son is working downtown now - so we might be stopping in at 06C a bit more often.

Mark C. · #4 01-10-2016, 01:21 AM

Hi Pete, Cant move the cowl back as I'm using Skybolts. As one person recommended to move the engine forward, I really don't like that option. I will ask Vans on Monday if acceptable a 1/8th " spacer plate in front of the 2.25 Prop extension would seem to work, but I might need longer bolts. Contact me anytime your coming in, I now have the plane at DPA.

BillL · #5 01-10-2016, 06:41 AM

Quote:

Originally Posted by Mark C.

Hi Pete, Cant move the cowl back as I'm using Skybolts. As one person recommended to move the engine forward, I really don't like that option. I will ask Vans on Monday if acceptable a 1/8th " spacer plate in front of the 2.25 Prop extension would seem to work, but I might need longer bolts. Contact me anytime your coming in, I now have the plane at DPA.

I think you need more than 1/4" clearance. Internally 1/2" is used, it will move that much outside too

I set up for 5/8" clearance on the right side.

I had the same issue for a different reason. I don't know about the cato spacer and back plate geometry, but if it just moves the prop but not back spinner plate then you are ok with a 2.5" (at least) spacer. If it moves the spinner too, then you will have to fill the spinner/cowl gap too. The right side will be the smallest cowl clearance. You must have the SJ cowl. Easy to sell the spacer and get another from Saber (Sam). It was even lower cost than the 2.25 when i got mine. Pete should look at it. Bite the bullet and do this right.

Vlad · #6 01-10-2016, 07:39 AM

Or sand/cut the front of the cowl where prop flange is and reshape it to increase the clearance.

YellowJacket RV9 · #7 01-10-2016, 11:04 AM

I ended up having to shave mine back a good bit due to an earlier error in fitting it. What I did was fill in behind the circular opening with more epoxy so that I was able to bring it back in front without running out of material.

Quote:

Originally Posted by BillL

I think you need more than 1/4" clearance. Internally 1/2" is used, it will move that much outside too

I set up for 5/8" clearance on the right side.

The plans specify 1/4", which I sure hope is enough, I'd hate to have to remove another 1/4"....

Chris

Vonsmallhousen · #8 01-10-2016, 01:17 PM

This has just append to me as well due to a fitting error. My poor wife just about bust into tears as we though we were getting close to moving the project to the airport.
I needed to move the face 1/4 inch for some reason at the top and about 1/8 at the bottom, after a little thought, a sleepless night and a good friends input we filled the ring with a layer of Floxed cotten and put layers of fiberglass over that on the first day. Let it dry over night and worked the face back slowly the next day. It came out real nice and and could not tell were we had moved it back except for the change in colours. It was not the huge problem that I thought.

Mark C. · #9 01-10-2016, 06:47 PM

Thanks guys, I think that's exactly what I'm going to do back fill the forward cowl ring on the inside with epoxy and fiber glass where its tight to the spinner. Mark it on the outside and grind down that area that was close and work to hit on the plus side of a 1/4" gap. I will confirm that fix with Vans in the morning. By the way I have a standard Vans cowling, Great input thanks, Mark C.

rvbuilder2002 · #10 01-10-2016, 07:50 PM

Quote:

Originally Posted by YellowJacket RV9

The plans specify 1/4", which I sure hope is enough, I'd hate to have to remove another 1/4"....

Chris

Actually, in most instances 1/8" is enough (1/2" would be overly excessive).
The only down side is that it can make it harder to remove install the cowl.