What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

Ellison TBI ---> Carburetor

bwellborn

bwellborn

I'm New Here
Patron
Hello all,

We have an RV-6 with an O-320 that has an Ellison throttle body injector on it. It has been quite a while since this unit has been overhauled, and given that Ellison is no longer around, we are considering making a switch to a carburetor.

I have browsed the VAF forums but haven't found much information on making the conversion or whether a cowl modification is required to fit a carb. Does anyone have experience making the swap, or advise against doing it?

I am aware of a document from Miravim https://www.miravim.org/4RE/AviationThrottleBodyInjectionEllisonRotec.pdf that lists parts to do a self-overhaul on an Ellison. If anyone has had luck doing this process, I would love to hear about it.
 
Maybe consider a Rotec TBI to replace the Ellison. I have heard good and bad about the Rotec. My understanding is the company has improved a lot. Should be almost a direct replacement. Not endorsing Rotec, just an option.
 
Thanks for the reply,

We’ve looked into Rotec a good bit and may consider them if a carb conversion is too extreme.
 
bwellborn said:
Thanks for the reply,

We’ve looked into Rotec a good bit and may consider them if a carb conversion is too extreme.
Click to expand...
I bought a Rotec TBI at Oshkosh and ended up not using it. I have a 0-360, not sure if you need the same model I have but I am gonna put it up for sale. Absolutely new! Let me know if interested
 
Dad tried a Rotec for a while to replace his Ellison, and had nothing but trouble.

Eventually he put a carb on it after fighting with the Rotec for a year or two. I think he had to modify the front of the air box a bit and angle it up because the carb is "taller" than the TBIs were.
 
I put a Rotec on my O-360. Ran great except too lean at WOT. Received no support from Rotec. Rocketbob did a lot of work to make one run ok. I got tired of being a test pilot every flight and put a carb on after trying many mods.
 
I replaced the Ellison TBI on my o-360 with a MA-4-5 10-4164 carburetor about 4 years ago. Runs great. Much better than with the clapped out, old, leaky, Ellison. If I recall correctly the carb is about an inch and a half deeper then the Ellison which lowered the Filtered Air Box by the same amount. Lucky in my case the FAB was still able to fit under the cowl, but I did have to cut and "bend" the front of the FAB to line up with the existing air scoop opening in the front of the cowl.

Edit: The MA-4SPA for an O-320 is not as deep (maybe the same as the Ellison?) so you might get away with not having to do this.
RV6 Engine.JPEG
 
Last edited:
MasonPhillips said:
Hey, I am in the exact position you were in last year. What did you end up doing and why? I am leaning rotec right now based on my research.
Click to expand...
We ended up switching to the MA-4SPA carburetor and have been very pleased with the conversion. We built a new FAB-320 airbox, which gave plenty of wiggle room for a perfect fit at the inlet, and installed a new throttle/mixture cable bracket from Van's. The worst part of the mod was waiting on parts availability and shipping from Van's.
1783694380754.png
 
bwellborn said:
We ended up switching to the MA-4SPA carburetor and have been very pleased with the conversion. We built a new FAB-320 airbox, which gave plenty of wiggle room for a perfect fit at the inlet, and installed a new throttle/mixture cable bracket from Van's. The worst part of the mod was waiting on parts availability and shipping from Van's.
View attachment 122758
Click to expand...
Aside: if you flip that Robbins wings heat muff on that front crossover end for end, the inlet gap will be in the gap between the two exhaust pipes, and will pull significantly more heat in when you open your carb heat door.
 
You must log in or register to reply here.
Back
Top