MVVS 26 with pipe mejzlik 18x6 or 18x8.
No problems.
/Lennart

http://www.viddler.com/v/f38f594c

Benchmark Prop: 18x6 @ 8,700 rpm
Prop Range: 16x8 thru 18x8
RPM Range: 1,400 to 9,500
Fuel: Oil w/gasoline mix 1:40

Originally Posted by JKimberly

Thanks for the feed back guys. Orthobird I think you may have been dead on. Pe I was hoping to get your response as you are the guru on these engines. Although I have it running great on the 16x8 I beleive I still may need to move to a larger prop because it is turning 8100-8200 rpm's at full throttle. Is that to high? and what should my max operating temp be?

That RPM is not too high that it will damage the bearings or engine.
if your engine is brand new, as you break it in, the RPM will increase..
to break it in
i do this:
full tank fuel
start it
use a tach
and increase rpm to 1500 or so
keep it there
stand by and listen to it
after 3 or 4 minutes, the rpm will go up
check with tach
if it is now 1600 or 1700 or so, then increase RPM to 2000
keep it there for another 5 minutes
after 5 minutes, recheck rpm, it will probably be 2100 or so
then increase again by 500 to 2500 rpm

keep doing this in stepwise fashion
eventually, you will go thru 3 or 4 tanks of fuel, and you will be at TWO.

I am using a Bisson Pitts muffler and evo oil mixed @ 40:1.
I did open high end more and it increased the rpm's, but was being careful not wanting to damage the engine.(I have made much progress though since I first started). After that I had to close shop for the evening to keep a happy girlfriend and watch the superbowl.

I will be leaving for business out of town for a week so I will not be able to proceed until I return. Keep the comments coming as all this info is very helpful.

Jamie

Here is a pic of my set up. I did rotate the head 180deg to get the spark plug on the bottom. This photo is right after installation fuel line is all secure and attached. I did install a T in the line for fueling. Does that restrict the fuel flow? Or should I add an extra line to my tank for fueling?

On mine, the rotated head didn't seem to make any practical difference to how the engine runs even though the plug is now facing away from the exhaust port. Pe may have more experience on this though as I have only ever done it to one engine.

The Tee in your fuel line may be giving you a problem. Are there any air bubbles in the line between the tee and the carb when the engine is running? If so - replace that line completely to a single line and use a seperate line for filling the tank (3 line setup). I have seen a lot of problems caused by tees (and filters) in the fuel line on gassers. This is because gassers use a pump to suck the fuel to the carb and they will easily suck air in at the slightest opportunity (we get away with tees on glows because most glows use pressurised tanks).

Also do you have any form of clamp on the fuel lines? The best way to clamp them that I have found is to use a small piece of fuel line stretched over the line. I don't have a picture of it here maybe someone else has one they can post.

aussie steve is totally correct. get rid of the Tee.

Originally Posted by JKimberly

I am using a Bisson Pitts muffler and evo oil mixed @ 40:1.
I did open high end more and it increased the rpm's, but was being careful not wanting to damage the engine.(I have made much progress though since I first started). After that I had to close shop for the evening to keep a happy girlfriend and watch the superbowl.

I will be leaving for business out of town for a week so I will not be able to proceed until I return. Keep the comments coming as all this info is very helpful.

Jamie

Not wanting to open the H needle more will sooner damage your engine by running lean than opening the H needle to best rpm. Then open more to the verge of rpm reduction. That would be the best setting for the engine.
The Bisson muffler reduces your rpm by some 1000+ as compared to tuned mvvs3266 pipe.

@ Steve,
I have no reports on negative effects when rotating the head to a desired position.

also, you do not want to tune engine to max rpm, as PE REIVERS has mentioned. if possible, use a tach, once you get max rpm, then open needle bit more to richen it so RPM decreases by 100 rpm or so. reason being, among other things, is that once plane is up in air, and different loads are applied to prop, the engine may work more and get hotter at times, then it may lean out to some extent, so you want to be ahead of that curve. you do not want it to be lean, and then lean more up in air, then you get dead stick.

As soon as I get back home I will remove the tee and run once again opening the high end watching the rpm's with a tach. All while still using the 16x8 prop. All this info has been great! Is there any certain klunk I should use to help with more fuel flow since I will be taking the fuel tank apart? Right now I am using a klunk with a felt filter.

Jamie

The clunk you are using is the best option IMHO. Especially if it is a genuine Walbro branded one.

The fuel systems on my gassers are :
3 line tank setup.
Walbro "felt filter" Clunk in the plane.
Walbro Felt filter clunk in the fuel can (because I use these clunks as standard on everthing)
Paper in-line filter on the outlet of the fuel can
NO inline filters, tees or any other sort of joiner in the line between the tank and the engine.
Clamps on each fitting of the fuel line (made up of a piece of fuel tube stretched over the actual tube)

I wash out my tanks with fuel before assembling them. Then after assembly, I wash them again before connecting them to an engine.

This works well for me as since doing it this way.

PS - there is always an exception and the sole exception to this is the plane I pictured in my earlier post. That particular plane has the tank located in the wing so I need a connection to be able to take the wing off the plane. For that one, I used a very good quality in-line fuel filter as the connector and placed some clear heat shrink over the filter as a precaution (even though it has o'ring seals, they have still been known to leak). That line is also the fill line on that plane - but not through a tee piece.

10/4 on the felt clunk and 3 line systems, the 2 line with a tee fitting gives you 3 more possible leak points , and another thing I do is solder on barbs on tubes inside tank and outside. it is a must for gas engines to have clean fuel and secure connections

Great! I did something right as far as the klunk. Yes it is a Walbro. As you can tell this is my first gas set-up. I have set up many nitro, even though this is a 26cc I want to get it right because I have a 100cc 3w on an aeroworks edge waiting in line.
As far as my fuel line clamps I used ty-wraps or zip-ties as some people call them. So Steve you think the fuel tube over fuel tube is a better choice? Same size tubing? Just strech it?

Oh, one more thing. Do you use a felt klunk as added filtration on your fill line in the onboard tank?

Here is QQ demo a new plane and a brand new engine, that have VERY LITTLE run time one it....
It is a decent demo, although some my say it doesn't have enough power in this plane. The prop he was using is a HEAVY prop to boot... A tuned pipe would wake it up as well as additional run time would yeild higher power.

QQ flying his 73" yak with evo26cc engine (8 min 51 sec)

Found a picture of the fuel clamp I use. Pe was the one who actually gave me the idea.

Yes, it is the same sized tubing and I use a pair of "bent" long nose plieers to stretch it over the line

I prefer this over zip ties because zip ties can in fact cause a leak (especially if barbs are not used). This is because the zip tie doesn't exert an even pressure on the whole circumference of the line and gives a pinch point where the tie "joins".

Barbs are a good idea, Dubro sells ready made ones that you install using soft solder (Or JB Weld works well too). Others use some solder to solder a ring of soft wire (such as electrical fuse wire). I must admit that I don't always use a barb but the flexible tubing I use is a tight fit over the branss tubing I use and the fuel line clamp does a good job of hilding it all together.

I don't personally use a filter in the fill line onboard the plane as I have a very good one downstream of the pump on my fuel can.