Voltage Drop to Starter Motor

[BQW]

Can some one advise on this, I have tried applying Ohms Law, but I am just getting ambiguous results.
Is it me ??
The car in question is a 1948 Ford Pilot converted from 6V electrics to 12V. But still uses the original Pos earth system with the Battery located in the Boot.
I therefore assume the resistance of the steel chassis is a factor?
If we assume the resistance of the 70 year old steel chassis from the battery + connection to the starter motor to be 1 or 2 Ohms, and the cranking current needed to turn over the 4 Itr V8 engine has got to be at least 35 Amps, surely that will result in some voltage drop through the chassis to the starter ?
Or are there factors, that I am not aware of ?

 

[Mottie]

I would have thought that the voltage drop would be greater through the cables connecting to and from the chassis than the actual chassis itself.

 

[Burnerman]

As above - the steel chassis will have negligible resistance and any culprit will be the earth strap(s) connecting the engine to the chassis.
You will need a heavy duty cable connecting the battery to the starter though!
Take a voltage measurement across the battery during cranking just to see where you are.
John

 

[Belle427]

What problems are you experiencing?
Starter motors draw a lot more than 35 amps, especially on cranking, it can be 10 times that.
Size of cable from battery to starter would need to fairly substantial, at least 50 mm squared at a guess.