Polling Question..... Just cause I can, that's why.

[Paul Taylor]

Just doing the poll for the fun of it.

But I do want to know if a LA .40 will have what it takes to haul the plane. Right now with the LA .40 it weighs in at 49.3oz on my new scale.

Thanks
Paul

[Mark Scarborough]

LA 46, easier to get a good run, more steady and its lighter!

[john e. holliday]

I agree with Mark as I have seen several "Tutor II" fly.  DOC Holliday

[phil c]

Have to laugh at that "lighter" comment.  What is it? 0.2 oz. or so?  The TT II's I've seen haven't been notably light.  49 oz. sounds pretty good.  With the right prop, venturi size, and fuel the 40 would be fine.  I agree that the LA 46 does seem to be easier to get running well though.  Like most series engines built on the same case, the smaller one seems to like to run a bit faster than the larger, and of course, the smaller one will not turn as large a prop.

[Mark Scarborough]

Ok Phil, yeah its like .25 oz I think, but hey its lighter! lol,, I have run both and personally I would opt for the 46 every day all day just because of the run characteristics.  10 22 fuel, 12.25 x 3.75 apc, launch around 9800 its a goer for sure,,

[Phil Coopy]

Hog out the head a little to lower the compression and they run pretty sweet......not my idea, but it works great.

Phil

[Mark Scarborough]

INteresting, Pat and I have been working towards the same solution , it does seem to stabilize them just a bit.

[Paul Taylor]

So how do you Hog out the head???

[Will Hinton]

I am definitely NOT an engine guy, but seems to me head shims would do the job instead of hogging it out.
I, too, would go with the LA46 - mine runs great with no mods except a ST51 NVA and a bore out to compensate for the lrager diameter of the NVA.  I'm swinging a 12" x 4,25 three blade Bolly that I nicked last year with my bigger ship and saw it was okay to cut down.
I have it on a Tuter two also.  Does very well.
Blessings,
Will

[Bill Gruby]

 FWIW       Yes, head shims will work but they have a major drawback. The change the glo plug depth at the same time. This is not a good thing. By machining the combustion chamber deeper it will lower the compression and not change the plug depth. If you need proof of this, take the long plug out and replace it with a short one.

  "Billy G"

[Phil Coopy]

Also by shimming up the head you are moving the squish band away from the piston top at TDC, making it less effective, which is bad for an even flame front during combustion, which in turn causes erratic power strokes.

Phil

[john e. holliday]

Isn't the face of the plug supposed to be flush with the combustion chamber?  DOC Holliday

[dennis lipsett]

I hope that you guys know that the OS40/46 are not designed for a long or short plug but the OS plug which is a medium.
Dennis

[Bill Gruby]

Isn't the face of the plug supposed to be flush with the combustion chamber?  DOC Holliday

  Yes Doc, you are correct but using the head shims you have moved the plug farther away from the top of the piston. The fa rther away you go the less effective the bang.

  "Billy G" 

[Terry Bolin]

I WAS having some trouble with my OS 40 running in the Vector then I called up Jim Lee and he sent me a Venturi and NVA .....WALA! Trouble free from that point on. Much simpler than Shiming or hogging out the head.... Give it a try.... you'll like it!
T

[Mike Foley]

  I Flew my Tutor II with a Tower 40. Plenty of power, excellent runs with a 11X4 APC and Mac's Pipe and a .010 head shim added. Absolutely no line tension problems. Plus the .018 chains are not required.