Zenith Carb

[Jerry09w]

I have just changed from an Aerocarb to a Zenith in a standard tri gear Sonex and am now testing this installation. I changed nothing but the carb so I can swap back if the Aerccarb seems better. Has anyone else made the swap, and if so any words of wisdom. Since the airplane lives at 4700 msl, I can not check the low altitude performance, but I did have it up to 12,500 today and survived.

[kmacht]

I believe that the zenith requires carb heat if you diddnt have it installed with the aerocarb.

[Jerry09w]

Even with the Aerocarb I added temperature sensors on both the input and output of the carb. I wondered about the no carbheat needed claim. In a stock Sonex using under cowl air you are effectively running carb heat all the time. Today it was 50 deg OAT at take off and -7 at 12500, The air into the carb never went below 100 deg, and the air leaving the carb never went below 55 deg. I would think there should no ice at those temperatures. Perhaps I am missing something but I do not know how ice can form at 55 degrees.

[lutorm]

I do not know how ice can form at 55 degrees.

The claim is that the ice forms *in* the venturi, where the throttle plate is located. Because this is a low-pressure region, the temperature there is lower than either before or after. By how much, I don't know.

[Bryan Cotton]

C182s with carbs were notorious for carb ice. They had a carb throat temp sensor. Maybe you could rig something up if you were concerned at all.

[Mike53]

I have a Zenith carb on a Hummel engine and I installed a carb heat box of my own design.I would never consider going without carb heat.A venturi was made for the formation of ice under the right conditions.Summer ,winter it cares not.Under the right conditions it will form and ruin your day if you can't add carb heat.
Up here in Canada it is a requirement,not an option .
E-mail Sonex and ask for there carb heat box drawing for the Aerovee.They do have one.
Cheers ,
Mike

[Bryan Cotton]

Would be great to see pictures of your installation and would love to hear about your ongoing progress. I have an Aerocarb but am still interested in what others are doing.

[Mike53]

Would be great to see pictures of your installation and would love to hear about your ongoing progress. I have an Aerocarb but am still interested in what others are doing.

Just click on the world thingy under the roundrel and then carb heat box.
Mike

[Jerry09w]

The goal was to try the Zenith carb in such a way that I could easily go back to the Aerocarb. A short tube was welded to a carb flange that was the same size as the aerocarb spigot. The same AN fuel fitting was installed. The mixture cable was connected as the choke and the existing throttle was used. The only change to the airframe was a hole for a #10 screw in an engine mount gusset to mount a bracket to hold the outer shield of the throttle cable. So far the carb has just worked, It has been tested from my field elevation of 4700 to 12,500 so far with no problems. It seems to run correctly at full throttle and my max EGT spread has gone from 200 deg with the Aerocarb to 100 degrees with the Zenith. The CHT probe clamped to the input of the carb is to measure the input air temp, and one of the clamps on the output hose is an EGT probe used to monitor the temperature of the air after the carb. So far it has only been tested with an OAT between 40 and 60 degrees.
Jerry