That's it........where is your battery grounded on your 351/400?

 

The engine block.

 

Every negative battery cable is fastened to the engine block...

 

yeah, grounds always have a good connection by being bolted to the engine block. If you are not sure where yours was, you can make a new one. Just find a 3/8ths or 1/2 bolt that you can maybe bolt your ground to. You'll get it some way.

 

I custom made all my cables out of 2/0 (solder and crimp ) .Battery to block , block to frame , block to body. I got the cable ,lugs and color-coded heatshrink from Napa .P.S. I like the Porsche . I had a 58 Speedster ,among others .

 

Like Goodold75highboy said, make sure your engine block is grounded to the firewall.
There should be a short ground cable, or a braided ground strap there.

Murph.

 

Let me rephrase that......Where on the block is your battery grounded? Yes I know it does not matter.

 

I've got batteries in my bed of my truck. Battery isolator between batteries and ground to frame and frame to block. Also have grounds to cab and bed. this helped my taillights get brighter also. Make sure everything is connected. 2/0 cable to winches frt/rear and to starter and grounds to anything critical. On my frame I found a hole and installed a bolt and welded to frame and then attached grounds as needed for my application.

 

I know you said 351/400, but on my 302 it's attached to the block right in the front, pretty much behind the alternator on the passenger side.

 

Ahh, okay.

The original location was on an exhaust stud on the 351M/400. But with 30 years on them, hardly any of them will still have them on an exhaust stud. Last rig I had someone rigged the negative cable on the ignition coil bracket!

I relocated it to a hole below the exhaust manifold on the passenger side, IIRC.

 

Same. I think the 302 had a dedicated spot for the negative cable eyelet. I like it. I can open the hood and see it plain as day.

 

Battery = Heavy ground to engine block + ground to fender. + braided strap from body to bed / both sides + braided strap at corners of body to frame... helps CB radio signal.

 

My dual battery truck had the primary battery grounded to the block near the alternator which is pretty standard. What I thought was odd was the secondary battery (factory dual battery setup) was grounded to the firewall. I abandoned the factory setup when I upgraded my alternator to 170 amp, but still used that firewall ground for the second battery thinking Ford had a good reason for doing it that way.