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Anyone replace their Ellison w/ a Rotec?

Hawg Driver

Hawg Driver

Active Member
Hey Everyone,
After way too much time wasted, I’ve given up on making my Ellison work again. Despite it working great for many years, I just can’t fix it…despite multiple attempts to clean, rebuild, adjust and repeat.

I love going upside down too much to go back to a carburetor and my only non-nuclear option I know of is going to a Rotec. Anyone do this before? How form/fit a replacement is it?
 
I'll be watching for a response as well.

Rotec certainly has factory support and I see they have combined the diaphragm so It's a single unit now. The two used to be separate.

It sure would be nice if they would service our old Ellisons too. I'm sure they are set up to bench test these kinds of units and probably know all the parts as well. It's prolly not a good business decision however.
 
Must be something going around - I got a PM from another Ellison owner the other day asking about my Rotec. :p

Bear in mind I have never owned an Ellison, but here's my reply to 'im:

I'm quite happy with the Rotec, however, went from a 40-4 (Mk 1) to a Mk 2 48/4-5 when I experienced vapour lock running Mogas (never on Avgas). I did notice an increase in indicated fuel flow when I did that, though actual flow remained relatively stable. I can't explain that except by the change in redcube outlet fittings to suit the new delivery hose.

I did have to drill out a few of the spray bar holes very slightly early in the piece (for the 40-4) but once I'd done that, she performed very well, apart from the above mentioned vapour lock.

When I went to the 48/4-5 I wrapped the FWF fuel system in exhaust wrap and have only had one more experience of it since - that doing an AOA recalibration with the slow flight stuff resulting in lower fuel flows. You'll probably need to either build a spacer or redo your FAB to suit the shorter TBI - though I'm not sure how high the Ellison is compared to a carb, and you'll also need to DIY an angle bracket for your throttle (runs fore/aft on the RHS of the RBI) and a bellcrank for the mixture (Runs L/R in front of the TBI). You can see the mock-ups I did for them on my Flickr gallery HERE.

Hope that helps, but if you've any specific questions, please let me know.
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An interesting aside. While at OSH I was strolling down the outside displays and noticed a Rotec TBI installed on the engine on display in the Corvair booth. Had a nice conversation with the gentleman there and he explained that they started going with TBIs after having trouble with use of a standard carb on their engines. Can’t remember what the specific issue was, but since they have used the TBI, that issue has been resolved.
 
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