Slick mag plug harness rubbing up against the firewall.

[SpecialT]

My experimental clip wing has a 150 Lycoming in it, with slick mags for ignition. The left mag wires/cap sits right up against the firewall to the point that several of the wires are tweeked pretty good. Does anyone have a suggestion as to the "path of least resistence" to a better solution?

1) Modify the fire wall with a pocket? The problem is their is a horizontal frame support running directly behind the firewall in this exact location.
2) Some kind of "extended" motor mounts to gain 1/2 inch clearance?
3) Modify, re-weld the engine mount, and recalculate the CG?
4) Some kind of 90 degree wire cap?
5) Install a different mag/ignition system on the left side?

[Hank Jarrett]

Re: Slick mag plug harness rubbing up against the firewall.

Did you check to see if you have the washers between the firewall and mount and between the mount and engine? They are missing on LOTS of planes (including both of mine when I bought them). With the washers you also get the proper clearance between the prop bolts and nose bowl. You might find that with that little more clearance at the back the cooling baffles fit better against the bowl and cowl. The washers are about 3/16" thick on mine for about a 3/8" move forward.

Hank

[NC36061]

Re: Slick mag plug harness rubbing up against the firewall.

Since its experimental, there are non-magneto electronic ignition options. I'm not familiar with how they install, but something I'd look into. The modern electronic ignition systems are more reliable than magnetos, and Slicks are not the most reliable mags out there from what I hear.

[SpecialT]

Re: Slick mag plug harness rubbing up against the firewall.

I'll look into the washers, thanks for the info.

My plane currently doesn't have electric. But I plan on wiring up a B&C accessory plate alternator which is good for 8amps. I don't think it would power an electronic ignition reliably due to voltage drop at idle.

[SpecialT]

Re: Slick mag plug harness rubbing up against the firewall.

Did you check to see if you have the washers between the firewall and mount and between the mount and engine? They are missing on LOTS of planes (including both of mine when I bought them). With the washers you also get the proper clearance between the prop bolts and nose bowl. You might find that with that little more clearance at the back the cooling baffles fit better against the bowl and cowl. The washers are about 3/16" thick on mine for about a 3/8" move forward.

Hank

I found a good picture of some engine mount washers at http://www.rvplane.com/?categoryid=10000&dayid=1077

I don't have any additional washers other than the plates that come on the Lord mounts and it doesn't look like I have any washers between the firewall and mount either. But between the firewall and mount would be more difficult to place them because a center lower bracket/support for the motor mount bolts in shear, so offsetting it would cause the support to not line up. Any ideas how to place washer between the firewall and mount in this case? Does anyone have a picture of washers between the firewall and mount? Washers to move the mount off the firewall would help with clearance on that starter contacter also.

Any opinions on washers in this location with my plane being aerobatic, only looking for opinions, not professional advice

Thanks for the ideas.

[3Dreaming]

Re: Slick mag plug harness rubbing up against the firewall.

I'll look into the washers, thanks for the info.

My plane currently doesn't have electric. But I plan on wiring up a B&C accessory plate alternator which is good for 8amps. I don't think it would power an electronic ignition reliably due to voltage drop at idle.

I have a friend who has electronic ignition on his Thorp T18. It needs electrical power for starting, but once running it produces it's own power just like a mag.

[SpecialT]

Re: Slick mag plug harness rubbing up against the firewall.

I have a friend who has electronic ignition on his Thorp T18. It needs electrical power for starting, but once running it produces it's own power just like a mag.

Do you know what brand?

[Hank Jarrett]

Re: Slick mag plug harness rubbing up against the firewall.

I took a look for photos of the washers and they always seem to be JUST out of frame. This photo (not of mine, actually of the plug cups) shows the one on the top right (the silver line between the mount flange and the rubber vibration dampener). The washer against the firewall is just barely out of frame. I will look for others.

Hank

[Hank Jarrett]

Re: Slick mag plug harness rubbing up against the firewall.

Found one on my plane (in fact there are TWO washers between the mount and firewall!) You can see one just in front of the oil cap between the engine and mount if you blow it up.

Hank

This photo was taken to document the over the top crankcase vent option. Cut my oil use to almost nothing!

[3Dreaming]

Re: Slick mag plug harness rubbing up against the firewall.

Do you know what brand?

E mag is the brand, and he is running 2 Pmags. They need power to start, and he says they need power below about 900 RPM. He said without ships power the enging will quit on landing rollout.

[3Dreaming]

Re: Slick mag plug harness rubbing up against the firewall.

Hank, his airplane has a 150hp Lycoming. The mount is different than a little Continental powered Taylorcraft.

[Hank Jarrett]

Re: Slick mag plug harness rubbing up against the firewall.

No experience with Lycs in Taylorcrafts, but the critical distance is the clearance between the prop and nose bowl either way. If the prop is too close to the bowl the washers will help, if not all they will do is cause the front of the case or one cylinder to touch the bowl (NOT good!). Just hoping he has enough room to gain a bit of clearance for the mag in back. Hope he gets lucky!

Hank

[Mark Bowden]

Re: Slick mag plug harness rubbing up against the firewall.

Hank, I’m curious where is your source for washers at the firewall joint? There are no washers specified I can find. The engine mount assy has a “washer” welded to it where it meets the firewall.

David, your clip wing must really get with the program with that motor, must really climb.

It’s hard to see from your photo, but you should never use the plastic/fiber lock washers firewall forward, they are only good to 250 F. Reduce your mount bolt length, they are too long, too many washers, install these per castle nut practices as that is what is specified.

Did you make a custom mount and bigger fuselage attach bolts, i.e.-6's?

These are not the real engineering drawings but the following list the hardware for the mount to fuselage:
1. F19 & 21 parts list catalog C65/85/O200/O235 mount
2. Instruction manual with 1941 engineering sketches
3. Service manual with 1945 engineering print copies

From F19 Parts List and 2/3 above for on C65, 85 & O200, Lyc 0-145
4 Bolt AN5-31
4 Nut AN310-5
4 Pin AN380-3-3 (The engr dwg copy calls out 382-2-2) No pin listed in F19 PL

F21 PL: O235: (also has same for smaller engines)
4 Bolt AN5-31 bottom, -35 top
4 Nut AN310-5
4 AN960-516
4 Pin AN380-2-3

Franklin install differs, from sketch in #2 above.
4 Bolt AN5-31
4 Boots Nut B-997
4 Washer B-9087

Hope this helps, Mark

[3Dreaming]

Re: Slick mag plug harness rubbing up against the firewall.

It’s hard to see from your photo, but you should never use the plastic/fiber lock washers firewall forward, they are only good to 250 F. Reduce your mount bolt length, they are too long, too many washers, install these per castle nut practices as that is what is specified. Mark

The nut looks to be a steel lock nut.

[3Dreaming]

Re: Slick mag plug harness rubbing up against the firewall.

Looking at your photo of the ignition leads it appears that you have an aftermarket set of leads installed. I think a set of factory leads would give you 1/2" or more additional clearance.