Magnum 46 carb replacement
 

Anyone know if other brand carb's are swappable with this engine?
I did a search, but the boolean functions aren't working (gonna have to ask if they are supposed to) so I got a thousand hits.

RE: Magnum 46 carb replacement
 

I too, would like to know the answer to this. I've got a pair of Mag 52's that are in dire need of a useable mid-range.

RE: Magnum 46 carb replacement
 

............................I too, would like to know the answer to this. I've got a pair of Mag 52's that are in dire need of a useable mid-range.........................

Dave, me too!!!!!!!! I have three different carbs now for the 52. All three are standard magnum carbs that fit the 40, 46, and 52. They all use exactly the same carb. Their service dept. sent me a new carb to try, and I robbed the carb off of my new 46 to try on the 52. They were all the same.... ratty, rich midrange that makes it want to deadstick! I am using an idle bar k & B plug just for insurance.

Ernie

RE: Magnum 46 carb replacement
 

I have purchased several new MVVS carbs for Magnum engines from 46 to 91 xls. Recently put one on a Mag 75 and receive performance similar to the 91.
Contact DarZeelon an RCU member who is the MVVS expert, he can set you up for much less than the stock carb. You may have to do some minor metal removal for a good fit but it's really worth it in the end. These are:D good bar-stock quality that do not leak air and always shut down when you want it.

RE: Magnum 46 carb replacement
 

Ernie: I wish Magnum would just redesign the carbs on these things. The engine itself is as strong as an ox on steroids! Even with that enormous leaky muffler! Yuck! If we all flew at WOT all the time it wouldn't be an issue, but, I'm not one of those guys, I have to have my throttle....

Thanks Gizmo... Maybe Dar will chime in for us...

RE: Magnum 46 carb replacement
 

Crash I'm sure a thunder tiger .40 .46 carb will fit. Perry carbs can sell you one that will work get. Measure your carb and maybe someone will have one that will fit?

RE: Magnum 46 carb replacement
 

The problem with the other carbs is they are all on about par with each other so no real gain.
In addition the Chinese Carbs cost much more than the MVVS, the shipping is even less for MVVS...

RE: Magnum 46 carb replacement
 

So where do I find these MVVS carbs? Looked on Tower, no go.

RE: Magnum 46 carb replacement
 

Not sure, but I think I've heard a rich midrange in the TT also.

Ernie

RE: Magnum 46 carb replacement
 

I have a Magnum 52XLS that I am breaking in and the carb is the worst I have ever saw, especially on the low end and mid range. After trying for several tanks to get a good setting, I snatched the Magnum carb off and replaced it with an OS4D from an old engine and the
difference is amazing. The OS carb is a bolt on replacement for the original carb (Use the OS bolts) and is a spray bar type carb. The engine responds to this carb like it was made for it, the low speed is easy to set and there is no mid range problems at all. I set the engine and let it idle for three minutes at each "clik" position of the throttle from idle to over half throttle and at each setting the throttle response is as good as it gets after a three minute idle.

I have the engine on a Hanger 9 Twist and and it turns a 12.25 X 3.75 APC prop 13,500 with the OS Carb, about 300 RPM's better than the stock carb for what ever reason. I tested a 13X4 APC prop and the engine turned it 12,750 RPM's. Either prop gives absoloutely
unlimited vertical and will pull the Twist out of a hover like the old Saturn 5 leaving the cape.

With the OS4D carb on the Magnum engine it is one of the smoothest running 2 stoke engines I have ever saw. I had a OS50SX on the Twist and the best it would do on the 12.25" prop was about 12,300. The Magnum is a good bit stronger and a whole lot quicker on spool up with the same prop.

Howard

RE: Magnum 46 carb replacement
 

That's exciting Howard! Thanks for sharing with us. Okay, it's an OS 4D carb for me, on my Mag 52 also.... as soon as I can get my hands on one.

Ernie

RE: Magnum 46 carb replacement
 

Hi Ernie,

Just came back from the field after an afternoon of flying:D. The Magnum 52XLS with the OS4D carb is absoloutely amazing. I have never saw a 50 size engine with this much power and the throttle response has to be seen to be believed. The OS carb I put on the Magnum came off of a old OS40SF and the only thing I did to it was put the O-Ring off of the Magnum on it.

I closed the low speed needle and then opened it up while keeping some air pressure on the fuel nipple with a long piece of fuel tubing. With the throttle set at about 1/32" open and the carb up to my ear. I set the needle to the point that I just heard some air then set the high needle to 2 turns open and put the carb on the engine. The engine started easy and I set the high speed needle to about 13,000 and then worked on the low speed. My initial setting was fairly rich on the low end. I turned the low speed needle in a quarter of a turn and saw a significant change but the "pinch" test showed that it was still rich. Overall I made three 1/4 turn adjustments and then one 1/8 turn and the bottom end was fine. This carb tunes the easiest of any RC carb I have ever adjusted. The carb is marked in 1/4 turns making it easy to set and you can see the needle without having to get a flashlight.

Get you one of these carbs off of an old engine in some body's junk box (New one is $60.00). This was one of OS's standard carbs and was used on a lot of their 40-50 size engines in the last 20 or so years. You won't believe how the Magnum performs and the power and performance with this carb has to be seen to be believed. Another plus is that after nearly two hours of putting the Twist through every violent manuever I could think of testing the engine, there wasn't even a drop of fuel anywhere on the engine or firewall. Love that spray bar carb!:D

RE: Magnum 46 carb replacement
 

How asome! I know a guy who will sell me a whole 46 SF engine for about the price of the carb alone. Yes, I will buy it right away.

I have an OS 32 and that carb might fit, but the venturi would proably be a bit small. Didn't you mention that you had to use the OS bolts to fit the carb?

Does anyone have a clue as to why the Magnum 46 seems to run fine with the same exact carb as on the 52???

Ernie

RE: Magnum 46 carb replacement
 

Hi Ernie:

I don't know what other OS engines the carb came on, but it did come on the following ones,
40SF, 40SF-ABC, 46SF, 46SF-ABC, 40VF-ABC, 46VF-ABC, 46SF-H, 46SF-HS, & 50FSR-H. The
Magnum carb bolts are 3X6MM and the OS is 3.5X6MM. The OS bolts will work fine on the
Magnum, actually they fit through the holes better than the Mags do which makes the carb
tighter on the O-Ring. The 32 size carb is a 7MM venturi if I am not mistaken and has a 13MM
throat. The 40-50 size has a 7.7MM venturi and a 13.5MM throat.

The carbs will work on different size engines mainly due to the fact that there isn't a lot of
difference in air (CFM) or fuel volume at WOT because the smaller engines usually turn more
RPM's then the larger ones. This is a highly simplified explanation, but pretty much covers it.

The OS4D carb has the same venturi diameter (7.7MM) and throat size (13.5MM) as the original
Magnum carb. What I like about the 4D carb, besides the fact that it is a spray bar, is the very
fine threads on both needles and the overall quality of the machine work. The 4D is a very easy
carb to adjust and the adjustments are smooooooooth!

Let me know when you try it and what you think...

Howard

RE: Magnum 46 carb replacement
 

I gave up on even trying my OS 32 carb because of the way the rear needle valve is permanantly attached to the backplate.....

More fun carbs on the way though. I have a friend who is going to sell me an OS 46SF engine, carb and all....:-) He is also going to sell me a 61FX carb which as the same mount as the 46's!
That IS going to be fun to experiment with on the Mag 52....:-)

I don't know how soon I will get around to trying this combo. Howard, if you or anyone else can get your hands on a 61 carb, you might try it sooner than I will. It does have the rear mounted needle though.... but oh well.

Ernie

Help need 4d carb for OS 46 SF?
Any replacements or other brands that will work?

Try justengines.com they have a variety

Absolutely, as I recall most every brand of .46 had the same type of carb size and mount. So Magnum, TT, etc. should be a drop-in fit.