UnPossible

UnPossible

Well Known Member
Well - I think I can see the light at the end of the tunnel wrapping up my baffles. However, this afternoon I had one of those "oh ****" moments.

When I have been taking my cowling on an off, I am shifting it forward to clear the baffles, then sliding it back into place. However, when the prop / spinner is installed, I won't be able to shift it nearly as far forward.

Below is a picture of my left air inlet baffle. Note the front edge of the baffle butts right up to the front edge of the K&N filter (meaing I can't really trim this back any further).

fmrk8m.jpg


Right now, the cowl overhangs the front of the baffle. I took some rough measurement, and it appers that I will need to trim the lower cowl at the blue line to clear the baffle.

4vfdq0.jpg


My questions are....

1) Any issues with trimming the cowl to the blue line or a bit more?

2) What gap (between the cowl and the baffle) should I shoot for to make taking the cowl off as easy as possible and still seal well? On the right side, the gap is ~1/8"... is that good or should I shoot for a larger gap?

vmvmmd.jpg



Thanks again,
Jason
 
thank you for your pictures... i'm at the same stage as you and i asked the same question. the answer was to shoot for a gap of 1/2" to 3/4" (i aimed for 1/2). this should give you enough room for easy removal of the cowling and still give you a good seal.

after cutting the ramp to get the 1/2" gap, i was running out of space to accommodate the filter. i think i will rivet an angle to the forward edge of the ramp (like in your pic) to gain some forward space and compensate this by trimming the cowl lip a little bit. i don't feel that it would be a problem to trim back the cowl at your blue line as long as there's still enough space left to secure the seal material and it still looks smooth.

suggestion... i don't know if it was your intention to cut the hole length of the blue line you've been drawing. i would keep the side part where the nutplates are to keep the aft most nutplate. this seems to be a high stress area so only two screws/nutplates are maybe not a good idea.

question: what's the purpose of that hole in the right ramp? you want to enlarge it for the heater scat tube flange?

again... thanks for the pictures, good timing. :)

Kay
 
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I have *exactly* the same question...my filter/snorkel is aft about as far as it can go, and I hit the same *aha* moment as you. I'm guessing it's going to mean trimming the cowling quite a bit (and the issue of making the two inlets look the same or at least not all stupid-looking by being vastly different may mean trimming the *other* side, too).

Anyone here have any pics or comments to help us out here?
 
Over lunch today, I carefully measured where I would need to trim the cowl for

1) Baffle Clearance (blue line)

2) 1/2" Baffle Gap (red line)

eftjc.jpg


As you can see, there will not be much of the front cowl inlet left.
I am planning on calling Vans later this afternoon to ask if there is a minimum depth needed at the cowl inlet, and what the ideal baffle / cowl gap should be to get the cowl on and off.

I would love to hear from anyone that has already tackled this step.

Thanks,
Jason
 
Jason,
On a slightly different tack, I angled my left side baffle in a bit so that it aligns more closely with the inlet. The baffle seal attached to the lip on the lower cowl does not mate up very well in the outside bottom lefthand corner. I wanted to minimise the gap. (the equivalent of where the curved fillet sits on the other inlet ramp).
Steve
 
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Why are you looking at 1/2" gap? Isn't there a detail on the plans that shows something like this:

______________ Aft Edge of Cowl Inlet
------------ Air Seal Fabric
______________________ Air Ramp or Side Baffle

Check Figure 2 Section A-A on p. OP-9 for this depiction and the Note that describes it.
 
You are correct that the plans does not show a large gap.....

However, reading thru VAF and speaking with a few builders, they seemed to recommend a larger gap so that you can get the cowl on and off without scratching up the paint.
 
FYI - I spoke with Vans this afternoon and they recommended a gap in the order of 1/4" to 3/8"...... I am going to shoot for close to 3/8" and go from there.
 
OK...I know this is off topic but I am almost at this stage as well. I just starting baffling and I have the same Vans pink cowling. Was wondering though, do I need a prop before I can start my fitting of the cowling? I don't currently have my prop and won't for a while..
 
You either need the prop or a correct spacer to simulate where the backplate from the prop will sit relative to the engine.

There may be a better way, but the way I did it was to tape a spacer (3/16" I think - not sure) to the back fo the prop spinner hub and then but the cowling up to that. Then you could use a real bright light in the engine compartement to mark the trim line a the firewall.

Without the prop or a spacer, you don't know how far forward or aft to position the cowling.

Hope that helps.

Jason
 
Go to Van

miyu1975 said:
OK...I know this is off topic but I am almost at this stage as well. I just starting baffling and I have the same Vans pink cowling. Was wondering though, do I need a prop before I can start my fitting of the cowling? I don't currently have my prop and won't for a while..
Click to expand...

Ryan,
There is a download document on the mothership that describes the spacers required for locating the spinner backplate without a prop. It contains info for both FP and CS prop configurations.


Other:
In regards to the snorkel filter position, I did prelim fit on 7A Lyc M1B a few days ago. It is obvious to me that to make an optimum installation, my snorkel must be modifed to allow the filter to move towards the centerline of the craft about 1/2 to 3/4" to center it in the cowl inlet and make room for a small curved filet piece to follow the inlet like non-snorkel construction. I am confused by some pictures I have seen on VAF in regards to the position of the #2 vertical baffle that extends forward from the valve cover. I read my instructions to mean that the vertical baffle should be bent inwards to nearly touch the cowl inlet. I see some people are not doing this and the baffle points straight into the "gap" between cowl inlet and cowl side. Have I missed something?

In addition, I will mod the snorkel such that the rear filter edge butts against the AL angle on the front of the cylinder. This will be a move of about 3/8" rearward for my snorkel.

In an unrelated spot, there is a minor interferance with my B&C 40A alternator mounting bracket. I will probably try the heat/push method to fix that area.
 
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rzbill said:
Other:
In regards to the snorkel filter position, I did prelim fit on 7A Lyc M1B a few days ago. It is obvious to me that to make an optimum installation, my snorkel must be modifed to allow the filter to move towards the centerline of the craft about 1/2 to 3/4" to center it in the cowl inlet and make room for a small curved filet piece to follow the inlet like non-snorkel construction. I am confused by some pictures I have seen on VAF in regards to the position of the #2 vertical baffle that extends forward from the valve cover. I read my instructions to mean that the vertical baffle should be bent inwards to nearly touch the cowl inlet. I see some people are not doing this and the baffle points straight into the "gap" between cowl inlet and cowl side. Have I missed something?

In addition, I will mod the snorkel such that the rear filter edge butts against the AL angle on the front of the cylinder. This will be a move of about 3/8" rearward for my snorkel.

In an unrelated spot, there is a minor interferance with my B&C 40A alternator mounting bracket. I will probably try the heat/push method to fix that area.
Click to expand...

Hi Bill,
Yep, agree with all you say here. That's pretty much what I did.

You'll almost certainly end up chopping the snorkel in two, fitting top end and bottom end then re-glassing the two parts together.

Another consequence of moving the top end of the snorkel inboard is that you don't get a straight run for the alternate air control cable along the side of the engine. I decided to put a 'blister' type extension on the side of the snorkel to move the alternate air 'door' outboard so it aligned with the rocker cover. The 'blister is effectively a flat cylinder in shape, about 3 in. diameter and 1 1/2 in. high. Hope that makes sense. I have seen a photo on VAF of someone else having done this.

In addition I also made the cylinder head air dam removable (or indeed swappable to a different shape/size) by riveting a piece of angle to the bottom of the air dam and utilising the filter retaining screws along the front of the cylinder to hold the air dam in place. I applied the same principle on the no. 1 cylinder air dam as well. Again, not my original idea but a very good one as it's easy to do.

Steve
 
"There is a download document on the mothership that describes the spacers required for locating the spinner backplate without a prop. It contains info for both FP and CS prop configurations."

Been looking on the mothership's site, no joy in finding the link...anyone have it handy?
 
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