Maxam

My Feedback: (62)

No pump or pressure needed with this set up! You will be very pleased. -Tom

HercN130AR

Hey guys, I'm new to this thread but have taken the time to read all within it. What a nice thing to be able to reference prior to purchasing a radial engine. I was fortunate enough to get a Greatplanes Waco for Christmas and really want to put an Evolution 7-35 on the front as it really looks great in a previous post here. I'm in Colorado so density altitude is a factor, especially in the summer. The Waco advertised weight is 13 to 14 pounds and 4 stroke range is 20cc. My question is, will this engine/airframe combo be able to fly scale while not pushing full throttle constantly. If not, would the 777 be too large for this guy. Thanks for all your assistance and advice, you guys have been a wealth of information.

Linkan2

Hello
Yes, you can have a 7-35 in Waco, the same weight as a PT17 from Great Plane.
I've been flying since 2012 with my 7-35 in a Stearman PT17
choice of propeller 18x8 & 17x10.
go for it
Lars

HercN130AR

Thanks much Lars, I feel like I've know you for a while as I have read most of your posts in here. Think I will order the 7-35 tomorrow!

Ed

HercN130AR

Lars, I want to also get the Saito carb and convert the 7-35 like you did. Does the CH Ignitions carb adapter for the 7-77 fit the 7-35? Thanks. Ed

Linkan2

Hi Ed
I do not think it fits on 7-35 engine.
I got help from my son to turn an adapter, you may have seen pictures of it.
Maybe CH ignitions can help you with those.
you need access to a turning machine
Lars

HercN130AR

Thanks Lars. During break in of the engine what synthetic oil did you use with methanol. I'm planning on using Wildcat 15% nitro 18% oil mixed 50/50 with methanol after break in, I'm just not sure what to use during the initial first three hours of running the engine. I've read Maxams thread on after run procedures and will follow that exactly. Thanks for all your kind advice! Ed

Linkan2

Ed, I mix my own fuel, with oil aero save from Fuchs.
mixing 8% oil and 6% nitro.
I do not think you need so much as a 18% oil when the engine is new, 10% is good

HercN130AR

Guys, any chance you can clear me up on which carb to use on the 7-35, is it the Saito FA 90r3 and/or FA120r3? Was also wondering if CH ignitions would make an adaptor for the 7-35 carb upgrade? Thanks!

Ed

Linkan2

Hello
It's the same number on the carburetor SAI90R3821
You can probably take it to 120r3 as the number SAI90R3821A.
There is no a difference in them what I can see.

CannonFodder

My Feedback: (23)

Hi All,

I am getting ready to finalize the 7-77 engine mounting and I have come to the point of adding thrust angle. I have a YA AT-6 1/5 scale aircraft the 7-77 is going in (previous post pictures), the fire wall is straight and I need 1 degree down and 3 degrees right. My thought was to build a full spacer plate that creates these angles in the 3 point mounting. This way the mounting plate of the engine mates fully to the plate and the plate mounts to the fire wall at an angle. Thoughts/suggestions?

Thanks for your advice, Mark

Sundownee

My Feedback: (30)

Am I missing something, when I bought my 7-35 from UMS, then later I bought the new updated carb for better performance. Now I hear people are using a satio carb, these better than the upgrade carb from evolution?

Maxam

My Feedback: (62)

That is the way I would do it! A band saw is great for this procedure. -Tom

HercN130AR

Guys, just received my engine from Horizon. It came with the silencer ring already installed. That saved me $130. It fits my cowling with room to spare but think I'll leave it off so it's easier to work on and it looks great on the Waco. I'm a little concerned after reading Tom's comments that this 7-35 engine is kind of fragile if run lean. I'm wondering if I should wait to run it after the Saito carb swap? Adrian from CH ignitions is going make up an adapter for the carb, what a great guy! Let me know what you guys think about breaking in with the stock carb. Thanks Lars for the carb part number and advice.

Ed

Maxam

My Feedback: (62)

Ed, you can try to run it. At full throttle if you cannot richen it then stop and get the Saito carb.

HercN130AR

Thanks Tom! Is it best to break in as the manual states, 90% methanol 10% synthetic oil the first hour, etc. or can I use Wildcat 15% nitro 18% oil cut 50/50 with methanol from start to finish, hour one to hour three? Thanks again for your advice and patience. Ed

Maxam

My Feedback: (62)

Sure! -Tom

HercN130AR

Sundowner, I've read in this thread that the 7-35 suffers lean mixtures at the high end of throttle travel with the stock carb. Maxam has had two 7-35 engines " eat themselves" after a few runs I assume due to too lean a mixture at full throttle. To preclude that, some others have switched carbs on the 7-35 to a Saito, much like the 7-77 carb upgrade from stock to an OS carb. The problem that I see with the conversion on our engine is getting someone to machine an adapter for the engine to accommodate the Saito carb. I've contacted CH Ignitions and asked if they could make an adapter (they have one for the 7-77 and OS conversion). They are willing to make an adapter for the 7-35 but I think I'll need to send him the Saito carb (haven't heard back from him). It's not too expensive to accomplish the conversion on the 7-35, probably less than $100 US as the carb is less than $50 and hopefully the adapter will be around the same cost as the 7-77 adapter (around $38). I consider this mod a safeguard to burning up valves on the engine for less than $100. Have you had any problems with your upgraded stock carb? Hope this helps as I have no experience yet but have read this thread several times to capture important information. Ed

Sundownee

My Feedback: (30)

Thanks Ed for the reply, I too have been following this thread but seemed to have missed this new revaluation to use a satio carb. I have seen a change running on the new updated carb from evolution for my 7-35,but to tell you the truth, I was having issues with it not being stable enough to fly at high rpm's. better tho but not good enough for me. I had decided that my source of methanol was not pure enough after testing it. So I had bought a 20 liter can of pure methanol from the drag race group. Because of my on going projects, I have put her aside for now. I need this engine to flawless at high end due to I am worried that this engine might not be enough power for my KMP AT6. 83" wing span.

HercN130AR

Sundownee, from what I've read here the engine runs very well at high throttle settings with the Saito carb. Lar's has put this carb on his engine and it seems to run well (there is a video of his PT17 Stearman flying after the mod in this thread). Maybe Lar's will comment further on the performance of the 7-35 after the Saito upgrade. I'm planning on using the engine in a Great Planes Waco 72 inch wingspan and overall weight of about 14 pounds. Let me know if your pure methanol helps. I hope we can figure out how to make these engines run well enough to trust them in our planes. Ed

Linkan2

Hello
what I first expected me in the modification to the carburetor Saito.
Where to end all turned on the needles, the engine went fine in amongst and sometimes very bad.
so when I started the engine after the change to Saito carb, I was suprised.
They where so much posetiv improvement
Here are some points that are better.

benefits of rebuilding
1 less fuel consumption
2 improved reliability of needle setting
3 little stronger engine, pulling a 17x10 prop easy.
4 engine is not as hot as before (old carburettor)
6 much better throttle characteristics at all rpm

have a good day
Lars Lindström

HercN130AR

Lar's thanks for your response! Can you tell me what you adjusted your low needle and high needle on the Saito carb when you first ran the engine with that carb. I have the Saito manual for the 120r3 so if you used that I have it. Thanks again Lar's. Ed.

Linkan2

Hi Ed
setting on Saito carb is high needle 2 turn out.
And low needle is always rich set at the factory.
so screw it in and listen to the engine.
But the clear that you can run the engine now with UMS carb

HercN130AR

Thanks Lars!

badangle

My Feedback: (1)

Guys....I want to put aside my 77 ucc radial....what do u recommend as to rust prevention