Rustler Merco .40

This is as much a request for comments from others as it is a product report. I just got a Rustler-Merco .40 and I've run it a couple of times on the bench. The exhaust/muffler configuration is a really neat idea: the exhaust port is about 45 deg. off the centerline axis and the muffler can be swapped around to configure the engine as either as side exhaust or a rear exhaust. Flexability in design. I love it.

My test stand is set up on a hinge so that I can rotate it to pitch the engine up while it is running. This makes it easy to simulate the 4-2 break. I've only run the engine a couple of times but it looks like it is going to be a very good engine for those who like the 4-2 break style of operation.

I'd sure like to hear more from those who have flown one of these. I was looking for a good match for some of the classic era size designs. The modern "60" 4 stroke and piped "40"s are just larger than I want to go for right now. I wanted something for the approximately 550 to 600 sq in area size plane and I think this will be a great match.

Goodness me, this is generating a lot of interest! Guess I'll have to blow my own trumpet!!!
Obviously I say it is a great engine, I declare a vested interest. What else I will say concerns the muffler in the rear exhaust position. There have been comments that you cannot get a 1" thick tank between the muffler and the bearers. I have to say - that depends. We have a small "blister" leading horizontally from the manifold, which blends into the main body of the silencer which is offset away from the bearers. With no mounting plates we have 7/8" under the blister and 1-1/8" under the main body. With 1/8" mounting plates you have 1" under the blister and 1-1/4" under the main body. The blister extends 1-1/2" beyond the backplate of the engine. This means to get enough room for some vertical tank adjustment you need the front of the tank 1.5" from the backplate.
If you buy one, - enjoy! BEst wishes,

Ian I have two Rustler40's and the standard 1" tank will not fit under the blister. It requires a custom tank. A change in the manifold would take care of it.
Ed

Ed, for all practical purposes I agree. It may depend on how close to 1" a 1" tank really is. It is not really practical to squeeze a tank under the blister. But you can get the distance if you set the tank 1-1/2" from the back of the engine. This increases the head of fuel relative to the engine when climbing/diving, and will assist the 4/2 characteristics if you like that sort of run. Hope the engines are giving good service. Regards,

FWIW.

Brett Buck and I each have one of these engines and have done our best to alert flyers to its many virtues. It is a perfect match for the early classic style 500 to 550 square inch airplanes. It runs a lovely 4-2-4 with a six pitch prop and is equally happy spinning a four pitch around ten grand for a constant speed low pitch/high rev set up. I ran it in the latter mode at VSC last year in the late lamented "smushed by Lincoln" Nobler and in the former mode this year in the Tucker Special.

It is a lovely engine and the rear exhaust option couple with its very light weight (for a modern higher performance engine) matches up well with the CG considerations for these light weight designs.

It does not have the raw power of the popular Aero Tiger .36s from Randy or the RoJett (and likely the new PA) light weight .40s. IMHO, these engines are better suited to the larger classic ships such as Jerry Phelps Patriot, Ed Southwicks Skylark and others in the 600 square inch range.

If it matter, Brett and I both "highly" recommend this engine. Like the little .20FPs, this engine will do the job right out of the box with little more than a conscientious break-in. Can't ask for much more than that.

>FWIW.
>
>Brett Buck and I each have one of these engines and have
>done our best to alert flyers to its many virtues. It is a
>perfect match for the early classic style 500 to 550 square
>inch airplanes. It runs a lovely 4-2-4 with a six pitch
>prop and is equally happy spinning a four pitch around ten
>grand for a constant speed low pitch/high rev set up. I ran
>it in the latter mode at VSC last year in the late lamented
>"smushed by Lincoln" Nobler and in the former mode this year
>in the Tucker Special.
>
>It is a lovely engine and the rear exhaust option couple
>with its very light weight (for a modern higher performance
>engine) matches up well with the CG considerations for these
>light weight designs.
>
>It does not have the raw power of the popular Aero Tiger
>.36s from Randy or the RoJett (and likely the new PA) light
>weight .40s. IMHO, these engines are better suited to the
>larger classic ships such as Jerry Phelps Patriot, Ed
>Southwicks Skylark and others in the 600 square inch range.
>
>If it matter, Brett and I both "highly" recommend this
>engine.

Uh, ditto. You take it out of the box, run it per the *original* Rustler/Merco instructions (not necessarily the overly conservative RSM additions, to wit, no extra head gaskets required, nor does it need low-nitro or FAI fuel!) and there you go.

One thing that's quite remarkable is that it realy doesn't seem to care at all which prop you put on it. Ted has run my RM-40 with everything from a cut-down 11-5 Rev-Up, a Tornado 10-4 3-blade, and a Tornado 10-6 3-blade - all with NO CHANGES AT ALL, just a twist of the needle. Hammers along in a 4-stroke to remarkable RPM.

It's not a 40VF, but it's plenty strong enough for any 35-sized classic plane. I think it's probably the best of the breed for Fox replacement motors.

List of do's and don'ts:

DO break it in thoroughly per original directions - when it doubt, more time is better.
DO run it per original directions, with regular 10% fuel as recommended

DO NOT reflexively add head gaskets unless you think the break is too strong (and it won't be)

DO NOT replace the venturi with a "through" spraybar. Stock system is fine and it doesn't need any "upgrades"

DO be careful when attaching "header". It might be necessary to open up one of the mounting holes slightly, and DO NOT force the screw into the holes.

DO keep the lock nut on the muffler tight. If you don't, the threads on the muffler will destroy themselves.

DO add an balsa (or LI-900 Silica shuttle tile material, if you have some lying around) thermal insulator between the tank and the muffler in the rear-exhaust configuration. The tank wiill be a very tight fit and we had some problems initially with the heating of the fuel tank and fuel making the engine go richer and richer as the run went on due to reduced viscosity. Slapped a bit of 1/8" balsa on the bottom of the tank, problem solved.

>>FWIW.
>>
>>Brett Buck and I each have one of these engines and have
>>done our best to alert flyers to its many virtues. It is a
>>perfect match for the early classic style 500 to 550 square
>>inch airplanes. It runs a lovely 4-2-4 with a six pitch
>>prop and is equally happy spinning a four pitch around ten
>>grand for a constant speed low pitch/high rev set up. I ran
>>it in the latter mode at VSC last year in the late lamented
>>"smushed by Lincoln" Nobler and in the former mode this year
>>in the Tucker Special.
>>
>>It is a lovely engine and the rear exhaust option couple
>>with its very light weight (for a modern higher performance
>>engine) matches up well with the CG considerations for these
>>light weight designs.
>>
>>It does not have the raw power of the popular Aero Tiger
>>.36s from Randy or the RoJett (and likely the new PA) light
>>weight .40s. IMHO, these engines are better suited to the
>>larger classic ships such as Jerry Phelps Patriot, Ed
>>Southwicks Skylark and others in the 600 square inch range.
>>
>>If it matter, Brett and I both "highly" recommend this
>>engine.
>
>
> Uh, ditto. You take it out of the box, run it per the
>*original* Rustler/Merco instructions (not necessarily the
>overly conservative RSM additions, to wit, no extra head
>gaskets required, nor does it need low-nitro or FAI fuel!)
>and there you go.
>
> One thing that's quite remarkable is that it realy
>doesn't seem to care at all which prop you put on it. Ted
>has run my RM-40 with everything from a cut-down 11-5
>Rev-Up, a Tornado 10-4 3-blade, and a Tornado 10-6 3-blade -
>all with NO CHANGES AT ALL, just a twist of the needle.
>Hammers along in a 4-stroke to remarkable RPM.
>
> It's not a 40VF, but it's plenty strong enough for any
>35-sized classic plane. I think it's probably the best of
>the breed for Fox replacement motors.
>
>
> List of do's and don'ts:
>
>DO break it in thoroughly per original directions - when it
>doubt, more time is better.
>DO run it per original directions, with regular 10% fuel as
>recommended
>
>DO NOT reflexively add head gaskets unless you think the
>break is too strong (and it won't be)
>
>DO NOT replace the venturi with a "through" spraybar. Stock
>system is fine and it doesn't need any "upgrades"
>
>DO be careful when attaching "header". It might be necessary
>to open up one of the mounting holes slightly, and DO NOT
>force the screw into the holes.
>
>DO keep the lock nut on the muffler tight. If you don't, the
>threads on the muffler will destroy themselves.
>
>DO add an balsa (or LI-900 Silica shuttle tile material, if
>you have some lying around) thermal insulator between the
>tank and the muffler in the rear-exhaust configuration. The
>tank wiill be a very tight fit and we had some problems
>initially with the heating of the fuel tank and fuel making
>the engine go richer and richer as the run went on due to
>reduced viscosity. Slapped a bit of 1/8" balsa on the
>bottom of the tank, problem solved.
>
>Brett

Brett, do you think I could use MA-25 or SOFI from the ET. I don't have LI-900. (smiles) The Silica tile material is pretty neat stuff, very light weight.

>Brett, do you think I could use MA-25 or SOFI from the ET.

Nice thing about ET insulation is that you just have to look around the pad- there's a lot of it just lying around after every launch.