need help 0520 carb set up

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snow bullet
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need help 0520 carb set up

Postby snow bullet » Tue Jan 09, 2018 8:47 pm

i’m looking for any information that I can get on setting up a Ma4–5 4893-1 carb On a 0520 Continental ,I was told that I would have to drill the main fuel nozzle but I don’t know what drill bit do you use and if there is any thing eles that should be done ?
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Gary S
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Re: need help 0520 carb set up

Postby Gary S » Wed Jan 10, 2018 8:28 am

Before you guess at how to set it up, contact GMAC 76 here on southern airboat. He set a carburetor for a 0300 up for me to put on a 0470. Fast return at a more than fair price. He was a pleasure to talk to and will steer you in the right direction.

Alvinlee1915
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Re: need help 0520 carb set up

Postby Alvinlee1915 » Wed Jan 10, 2018 9:18 am

Norman Clay at Innovative Accessories might know. I know he knows a guy that only works on aircraft engines.

GMAC 76
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Re: need help 0520 carb set up

Postby GMAC 76 » Wed Jan 10, 2018 10:26 am

the 4893 is a 470 carb with the 187 throttle bore while it will run the 520 it is not the right carb for that engine...the 520's were all fuel injected and when changed over to carburation the best carb for them is a 540 carb or a 6AA helicopter carb with the larger 277 throttle bore....im sure you can drill the main jet to get more fuel and change the economizer setting on the 470 carb but the 520 cubic inch engines also need more air to go with the added fuel and that is not possible with the 187 throttle bore but is with the 540 carb and the larger 277 bore...like I said the 470 carb will run the 520 but you will never get the full potential out of the 520 with the 470 carb no matter what you do to it....imo

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Thu Jan 11, 2018 6:33 pm

i will look for a 10-4404 off a 540

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Re: need help 0520 carb set up

Postby GMAC 76 » Thu Jan 11, 2018 8:47 pm

there ya go!!!!......gary barber on SA facebook has some 540 carbs that are take offs...might give him a try...they are getting harder to find...good luck

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Thu Jan 18, 2018 7:26 am

got a 4404 going to try it today is there anything i need to do to it or just bolt it on and pull the trigger ?

GMAC 76
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Re: need help 0520 carb set up

Postby GMAC 76 » Thu Jan 18, 2018 9:29 am

might have to adjust the idle mixture screw to get a nice smooth idle and the idle rpm screw for your desired rpm but if its a true 4404 and the jet and economizer are right then pull the trigger!!!!!!

Sisk Rifles
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Re: need help 0520 carb set up

Postby Sisk Rifles » Thu Feb 01, 2018 4:39 pm

Does anyone have a spec sheet or know where I can find specs on the above mentioned carbs ? I have a 470 converted to 520 with the original carb.
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Charlie

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Re: need help 0520 carb set up

Postby GMAC 76 » Thu Feb 01, 2018 9:23 pm

Don't know exactly what spec sheet your referring to......there is no carb oem for a 520 they were all fuel injected....the 470 carb is too small to properly run a 520 ci engine but the Lycoming 540 carbs are the right choice .... ...if ya have a 10- part number for the carbs you need info on I have the parts sheets and exploded view of all the carbs if that would help ya out

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Re: need help 0520 carb set up

Postby Sisk Rifles » Thu Feb 01, 2018 10:35 pm

I was wondering if anyone has tested these on a flow bench to test the differences.
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Charlie

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Re: need help 0520 carb set up

Postby GMAC 76 » Fri Feb 02, 2018 10:22 am

im sure someone has maybe joey beyer or someone that works in a fuel systems shop......my only testing was in the real world of airboats ..you know same engine same prop same boat and then put a 470 carb on it and a 540 carb and compare how the engine preforms as far as idle, acceleration, wot rpm and cyl head temp etc. and the 540 was better everytime....only stands to reason that if ya ask a carb designed to feed a 470 cubic inch engine to prefom on an engine that is 70 cubic inches bigger it s gonna fall a little short and because they have different size bores the flow will definetly be different but I guess it would be interesting to see how much difference

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Tue Feb 06, 2018 8:34 pm

i found 4404 carb it seems to work ok
but i seem to have fould a plug so its running rough

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Re: need help 0520 carb set up

Postby GMAC 76 » Tue Feb 06, 2018 8:45 pm

well if the carb is set up right ya sure picked a good one for your 520...4404 is top of the line everybodies looking for 'em.

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Thu Feb 08, 2018 8:06 am

so o have been playing with my boat a bit and itseem to Be running very rich between 1500 rpm and 2000 RPM .I was talking to and aircraft engine builder and he mentioned when they do the aircraft conversion they also change the crossover tube on the back of the motor to the 04 70 crossover tube which is a smaller diameter has anybody heard of this ?does it make a difference ?and if so what does it do?

GMAC 76
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Re: need help 0520 carb set up

Postby GMAC 76 » Thu Feb 08, 2018 9:45 am

is the lean/rich assembly working properly and has the economizer been adjusted...ya have to tweek things like that when ya put a carb on an engine that it wasn't built for...there might be something to that crossover tube change out since the stock one was for FI and now your carbureated.... the tube is to equalize vacuum and pressure on the intake so all cyls draw the same...check your plugs and see if the front and rear cyls are burning the same ...one of the 2 may be the ones burning rich at that rpm....the plugs should tell ya

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Fri Feb 09, 2018 6:57 am

Yeah the mixture control seems to be working fine but what do you mean by economizer is that the idle mixture control screw on the front of the carburetor ? And yes the two cylinders that are closest to the crossover tube at the back of the motor seem to be running much richer than all the rest

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Fri Feb 09, 2018 7:00 am

also when I had the plugs are checking them did a compression on the motor but I didn’t have a proper differential compression tester to do with the way they do in the airplanes I just had an automotive style I got about 150 psi on all cylinders is that normal ?

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Re: need help 0520 carb set up

Postby GMAC 76 » Fri Feb 09, 2018 10:25 am

the economizer is an airjet found at the base of the carb where it bolts to the engine...it is behind the dime size plug with the brass over rubber washer....usually after it is set the plug is safety wired...when we start frankenstiening these things then we need to change different settings...a flat screwdrive is all ya need to screw the jet either in or out to get the best performance...I also talked to a friend who was having the same problem with the rich running cylinders and that he changed the crossover pipe and it did indeed help....learned something everyday with these things...I would also imo say that compression is not an issue with your engine

snow bullet
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Re: need help 0520 carb set up

Postby snow bullet » Fri Feb 16, 2018 7:19 am

i change the crosover tube and it made a huge diffrence in running quality
no more snoking at mid range and much better Throttle response

Sisk Rifles
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Re: need help 0520 carb set up

Postby Sisk Rifles » Fri Feb 16, 2018 10:28 am

Some of these engines will run better with the crossover tube removed and the induction ends plugged. Verified with engine monitor that has individual cylinder and exhaust temps.

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Re: need help 0520 carb set up

Postby Hardtail » Sat Feb 17, 2018 9:40 am

Heated Carb air.jpg
Heated air
I had an interesting experience running in cold weather in Minnesota, Seems the cold air would ice up the carb and slow to an idle till the ice would melt then speed up till ice would buildup too much again, so I now have a duct connected to the carb and draw warmed air from under the cylinders, being I live in Florida I haven't had a chance to try in in single digit weather yet, I had no problem when the temperature was above 20 degrees, but when it was in the low teen and single digits temps I could not get enough power to run dry, was wondering if you have had similar experience, Or do you already have carb heat?


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