503 Carburator Vibration

[Tjoek]

I am noticing while in flight at cruising rpm that my Windlass 503 DCDI's front carburator vibrates notably, while the back carburator (i.e. one closest to prop) appears to have no vibration at all. I do not feel any vibration on the airframe. Thus, visual observation only. I would appreciate any views. In case its relevant, I have noted that some paint on the tips of my P-Prop is starting to peel off.

[BOOMARANG]

Hi Tjoek

I have no explanation why this is so, but I noticed the same on my 503 while on the ground. One reason could be that the connecting rubber of the front carb may be softer?I solved it by fitting one of those filters that cover both carbs.

What really intriques me about your post is , how on earth do you manage te see the front cab while in flight! The best I can do is to seeing the tip of the prop when I look back...............or maybe I must loose some weight!

regards

[bobthebuilder]

Over what rev range does it vibrate? Idle only?

[Tjoek]

From around 5500rpm. Below that I do not see any vibration. My prop has a fine pitch to I spent much time at high revs.

[kloot piloot]

I assume that your clamps, rubbers and filters are all tight as per spec, and your carbs are balanced.

Your front carburator choke or throttle cables are shorter and might be "tie downed" too tight and too close to the carb. Under max torque, your engine will "lean" away from neutral position and cables will pull carb against torque.

Slacken front carb cables. Give them some play

[Tjoek]

Thanks Kloot. Today I confirmed that all cables have enough slack. I also swapped the two carburator mount rubbers. Front carburator still vibrates.