Grounding locations

[JSabah]

I can’t recall where the origins ground cable(s) went and I don’t have my pictures handy, nor am I certain that what I took apart was correct. I’ve converted to a 12v system (and neg ground), not that it should matter except for gauge. I have other cars with up 4 or 5 grounds (bat to body, to engine, transmission and 2 to the radiator) but on my ‘49 Plymouth I only recall having 1 braided type. What is necessary and/or recommended - location(s) and gauge

Thanks 

[Go Fleiter]

Hallo!

 my 1951 P23 came with one wide braided strap from the batt ground to one of the bolts

of the cylinder head. The bolt´s hex head has a smaller tapped hole for an extra screw to hold

the strap´s contact eye.

The P23 engine sits in rubber mountings, so ground has to take a long way over accessories as

generator, gas linkage, transmission, propeller shaft....

 

  That is sufficient and works until age and rust let resistances between engine- frame- body- parts grow.

 

On these old cars I provide at least one additional ground between batt and body.

 

Greetings from Düsseldorf!

Go

Edited February 4, 2020 by Go Fleiter

[Sniper]

When I converted to 12V I added an additional ground strap.  Ran it from the battery negative clamp bolt to the radiator core support using an existing bolt to secure it.  All my front end electrical stuff has dedicated grounds run to that same bolt.  I ran a dedicated ground line to the trunk and all the electrics back there have a dedicated ground tying into that line. 

 

All my gauge cluster stuff is done the same way.  In fact the only electrical stuff without a dedicated ground wire will be the door jamb switches because they use the connection to the body as the ground source.  All of it using uninsulated connectors crimped and soldered with heat shrink applied.

 

Overkill?  maybe.  But I choose to never have another electrical issue.

 

 

[greg g]

The factory location is on a special bolt that holds the generator bracket on. The other thing you might want to do is run a strap from the fire wall to a bell housing bolt or the frame.

Edited February 4, 2020 by greg g

[Dodgeb4ya]

On the 1949 Plymouth the battery ground cable connects to a specially tapped head bolt..

Second head bolt back from front of head on the drivers side

Picture shows it on a 1949 plymouth fastback engine...original cable shown too.

[Sharps40]

Just wired my 37 dodge.  Grounds are now...

 

LR body to frame.  

 

Fuel sender to frame.

 

LF body to frame. 

 

RF nose to frame.

 

R bell housing/block to frame. 

 

Battery negative to frame.  

[kencombs]

While it was never factory, I prefer multiple grounds also.  With only a starter, lights and maybe a radio, ground integrity wasn't an issue back then.  But, with  the possibility of using modern electronics at some point, ground potential differences could present problems.    So, I ground the battery directly to the engine, (where isn't important IMO), Frame to engine, and body to both frame and engine.  And, a separate dash ground to the frame or engine, just in case the bolted in dash points don't make good contact.  Wire's cheap, compared to issues with your modern radio, ignition, bluetooth etc. 

[JSabah]

4 hours ago, Dodgeb4ya said:

On the 1949 Plymouth the battery ground cable connects to a specially tapped head bolt..

Second head bolt back from front of head on the drivers side

Picture shows it on a 1949 plymouth fastback engine...original cable shown too.

Thank you...I guess that my engine builder thought it looked better on the back right corner ?.  I've now moved it to the proper location.  Thinking about a second ground to the radiator support (from the battery) and a 3rd from the bell housing to the frame.  As the car body is wood, I have some grounds to both (rear lights to floor, fuel pump to frame, headlight relay to radiator support, added ground wire fuel sender to floor, etc).

Edited February 4, 2020 by JSabah
added info