Sport Pilot Talk

Got my very first carb balancing done today with my wife as my helper

The engine was running pretty rough and once I got the CarbMate connected, it was at the right most limit ( +4 ) at 3000 RPM. Took us about 1 hour , stop , adjust and go etc etc ...
Interestingly , I was only able to synch it up at 1.0 , when going down to 0.5 I couldn't get it closer than +1 ( yellow.) Did the same thing for the idle 1800 speed and in the end the engine runs butter smooth.

In the process I noticed that my radio interference I have been experiencing recently , which was related to engine RPM , is now completely gone - it must have been related to carbs being out of synch.

How do you do that? Are you turning mixture screws or adjusting cables or what? I'm just curious.

Yeah, you get both screws loose on each side and then adjust the throttle cable (move it forward or back to match the other side of the engine) , tighten the screws , run the engine - until both sides of the engine are balanced.

The CarbMate itself is an electronic version of vacuum gauges with simple light diodes to indicate which side is unbalanced and how far etc ...

Thanks.

Warmi wrote:
In the process I noticed that my radio interference I have been experiencing recently , which was related to engine RPM , is now completely gone - it must have been related to carbs being out of synch.

Hard to see how the two might be related.

When syncing the brass cable stop should be slid back about 1/2” to get it out of the way or it will interfere with the idle setup. Once idle is synced then you move it back up to the stop and tighten the Allen screw. This keeps you from over powering the cable pull and bending the idle stop screw plate. If some day you’d like to try a set of gauges you’ll find them much easier and faster to use. You can diagnose with gauges, but not the electronic devices.

I am sure you are right but the bottom line here is that you are a professional doing this type of work daily but for me , I am just attempting to do basic maintenance and the benefit of vacuum gauges providing much greater diagnostic info, will be lost on me since I won’t be able to utilize that info anyway.
In other words, if, for whatever reason, I am unable to balance carbs using the Carbmate I will take the plane to professionals like you as at that poin the issues is already probably beyond my pay grade

Regardless of which carb sync tool you use my point was the brass cable stop needs to be loosened and back away to properly set the idle otherwise it keeps you from lowering the idle on either carb that you may need to adjust. Then once you're done slide it back in place and lock it down.

Roger, none of the planes I work on even have that cable stop. Is it a recent addition, on the newer engines?

drseti wrote:Roger, none of the planes I work on even have that cable stop. Is it a recent addition, on the newer engines?

I've never seen the cable stop either, what purpose does it serve? ( I know, to stop the cable ) , but could you be more specific? I was thinking of replacing all my cables in November at my annual.

Looks like it would prevent the cable from being pulled beyond the point at which something would break or get bent, etc.

The cable stop is only on planes that have no other stop. Many planes have stops in the cockpit throttle system. Most of these brass cable stops are on planes with a vernier type throttle. That type has no stop so the pilot can easily pull back too hard and bend the carb idle stop screw plate. It can be bent back in place, but the danger is you'll pull it back so far you'll kill the engine.
For instance RV12 have them. If your plane has no throttle stop then this is HIGHLY recommended that you put one on.

roger lee wrote:The cable stop is only on planes that have no other stop. Many planes have stops in the cockpit throttle system. Most of these brass cable stops are on planes with a vernier type throttle. That type has no stop so the pilot can easily pull back too hard and bend the carb idle stop screw plate. It can be bent back in place, but the danger is you'll pull it back so far you'll kill the engine.
For instance RV12 have them. If your plane has no throttle stop then this is HIGHLY recommended that you put one on.

Thanks Roger for the explanation and it makes more sense now why some have it and others, including me, dont. I have hard stops on my throttle handle on my SportCruiser so no cable stops needed.

I just balanced the carbs in a Remos, and it needed them.

The picture that was included was from a Rv12 plane I pulled off of the net- it was meant to be a generic carbs cable setup picture ...
My particular plane has the stop installed in the cockpit so I don’t really need anything else.