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Where to install the engine ground connection on a IO-360 Lyc?

ao.frog

Well Known Member
Hi gang.

I'm wondering where you all have installed the ground connection on the engine?

One end of the ground cable goes to the battery, so that's easy, but where on the engine do I connect the other end?

On my first 7, the engine manual (Extreem IO-360) showed where to install the ground connection, but on my new -7, the Lycoming manual doesn't show any main ground at all, as far as I can see.

So, instead of guessing any further, I ofcourse put up a post on this great forum. :)
 
Instead of grounding to the battary you might just consider grounding directly to the firwall as I assume you have or will install a ground bus on the firewall to run most of your grounds. I installed a back to back ground bus inside and outside of my firewall and ran the engine ground to the post holding the ground bus in place on one side and ran the battary ground to the post on the other side of the ground block.

The engine side of the ground bus can be installed on almost any nut on the back side of the engine that is handy. Just make sure the the ground strap has a little play for vibration purposes.
 
Found a pic on google, there is a lug just above the lower engine mount on both sides. I bolted my ground strap to the lug on the right side just above the lower mount slightly rearward of the oil dipstick. It's my understanding that any bolt on the back of the engine can work, but its best to use the lug on the case

feb1243.jpg
 
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Be sure it is big enough

If you do install a ground conductor from the engine to the airframe, remember that it has to be large enough to carry the current required by the starter motor, as do the terminals at each end where it connects to the engine crankcase and to the firewall
 
my friends rv7 w/lyc io360was very hard starting. we had a tech counsler come over and he asked to see the engine ground strap. so we took the cowl off and showed him. he asked us to unbolt it, we did, he looked at he place we bolted the wire to, he asked whats all this engine paint doing here? remove it. we did. engine spun over much much faster and started right away. never a problem again! food for thought.
 
I got my engine (IO-320) grounded to the firewall (one of the lugs on the forest of tabs ground block on the interior side). The other lug on the firewall will connect to the negative side of the battery. I used 2AWG welding cable and connected it to the vacuum pump accessory location.

IMG_3143-M.jpg
 
ground strap

I got my engine (IO-320) grounded to the firewall (one of the lugs on the forest of tabs ground block on the interior side). The other lug on the firewall will connect to the negative side of the battery. I used 2AWG welding cable and connected it to the vacuum pump accessory location.

IMG_3143-M.jpg
Hi Bruce, did you end up staying with this location? Looks pretty clean to me.
 
Pretty much exact same setup, but used braided grounding strap (forget which vendor I got it from)...works great, easy to inspect pre-flight.

Same here. Got the strap & terminals from Stein. Easy to crimp on #2 terminals.
 
I ran mine up front to the starter pad. That's where the heavy load is.

+1

Use the nice ground lug on the starter motor - that is what it is there for. Wire size to the starter ground lug the same as you have providing power to the starter. Ground wire from the starter then runs to the common ground lug on the firewall (I use the one with the "forest of tabs" on the cabin side").

Carl
 
I am the odd man out.

I used the case as noted with a braided strap from B&C. Thanks for the pict, Andy.

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I got my engine (IO-320) grounded to the firewall (one of the lugs on the forest of tabs ground block on the interior side). The other lug on the firewall will connect to the negative side of the battery. I used 2AWG welding cable and connected it to the vacuum pump accessory location.

IMG_3143-M.jpg

This is where my ground strap is bolted on to the engine and then from the same bolt on the FW goes to the battery so in essence a direct [copper] path from the battery to the engine, intercepted by the airframe.
 
ground straps

Here's what I ended up doing. Click on image for more pictures.

 
I used that hole on the case flange just above the lower right engine mount - the one with the red arrow in the picture above. I just tapped this hole for the appropriately sized bolt and used a toothed lock washer to secure it. It's easily accessible with the engine mounted, and not in the way of anything else on my engine.
 
Could be worse ...

my friends rv7 w/lyc io360was very hard starting. we had a tech counsler come over and he asked to see the engine ground strap. so we took the cowl off and showed him. he asked us to unbolt it, we did, he looked at he place we bolted the wire to, he asked whats all this engine paint doing here? remove it. we did. engine spun over much much faster and started right away. never a problem again! food for thought.

This could have been worse, and I had it happen, on the first few attempts to start my O-360. Actually fried a wire to the ignition switch. The engine barely turned over with the plugs installed, but had turned easily on the test with plugs out of the top. After a 2nd or 3rd attempt I smelled a hot wire, saw the Tefzel deformed, and felt the heat to be sure my eyes were seeing the problem. :(

Due to a distraction, I'd laid the ground strap on the bench one day and never connected it to the engine or the firewall. An ignition switch lead had become the only "ground wire" because it was the only path. Replaced the lead, installed a ground strap, and cautiously tried the starter ... ZING, sounded good. :)

It has given me cautionary approach to starting the engine. If ever it fails to turn over well, I will check the battery voltage 1st and the ground strap continuity 2nd, before cranking away at a crawl.
 
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