Engine ground Strap

[Daniel Haumesser]

In the process of installing Bogerts copper cables in my 1960 Comanche 250, i came to realize i dont have an engine ground strap. From what i have read, there should be a tab at the pilots side lower engine mount and that should be grounded to one of the oil pan bolts? My plane was built as a 180 but was convertedvto a 250 and i woild assume the strap dissapeared then. No tab either and i would rather not mess with the engine mount bolts to put one on.

Heres my question: there are two mounting holes incorporated into the passenger side lower engine mount support that arent being used. I suspect they are for mounting a different kind of fuel pump. Can someone think of areason why i shouldnt ground from that point to one of the oil pan bolts. The two points are perfectly located and make a clean and neat install. I already installed the cable as i described and the ground test run went swimingly. The starter cranks over noticibly faster and thats still with the old starter.

By the way, running the cable from back to front was a breeze! One guy feeding from the back, me pulling and guiding from under the panel on the passenger side and another guy in the engine compartment pulling. Took all of five minutes. I almost feel guilty.

[Clarence Beintema]

Hi Daniel,

There are usually two ground lugs on the vertical tubes of the engine mount frame, one on each side. There should be two braided ground cables connected to one accessory cover bolt on each side of the engine. There should be no reason that you can't add a ground from the engine to a convenient spot on the mount.

If your new cables installed in five minuts there is something wrong or missing. In all of the Comanches I've worked on the cable is supported in clamps at every bulkhead under the floor boards. Left unsupported could lead to a chafed cable and a spark show some day. I would suggest looking under the floor for the clamps.

Clarence

[Michael Bryant]

Just replaced mine in my 1960 180.

Removed the cockpit floor panels. The old cable was routed thru some rather useless adele clamps that were for wire bundles about 1 & 1/2 to 2 inches in diameter. At the time I removed the old cable, there were 3 coax and 2 18 gauge wires running through these clamps. I found it easier to remove the old cable by cutting it in to smaller pieces.

Then removed the old adel clamps, some old coax antenna cables that led to nowhere, and an old radio rack under the copilot rudder pedals.

Removing the 6 nuts/bolts from the plastic cable cover running up the inside firewall behind the copilots rudder pedals required two people, one inside holding the bolt head and one outside in the engine compartment cranking the nut.

Routing the new cable went very quickly, I did it mostly by myself with some help from my A&Ps when it came time to secure it. Securing it at the firewall was the most difficult, mainly due to limited access. Again, a two man job as the bolt head and nut are on opposite side of the firewall. New adele clamps were installed to replace those 2 inch useless ones. I was able to loosen and reuse one old adjustable adele clamp under a panel that was rivets in around the fuel strainer.

All told, probably a couple hours of work. I did mine in conjunction with a Plane Power Alternator Conversion.

Michael

[Daniel Haumesser]

Thanks for the replies and info and advice.

I must clarify my comment about the easy routing of the long cable. It went quickly only after the floor panels were removed, clamps removed and anything else that would cause binding cleaned up. I cut the old cable just ahead of the battery and attached the new one to it. With three of us carefully pushing, pulling and guiding, it went quickly pulling the old out w the new attached. The prep work took a few hours though. The routing under the floor was already cleared of unnecessary wires and cables from a panel upgrade last fall.