Wiring loom for Perkins 4108

[srp]

Making up a new loom, but I have no more than a rough idea what sort of current the cable has to carry for some parts of the loom. Bits I'm stuck on include the charging cable from the alternator, and the cables to the thermo-start glow plug in the manifold and the cable from the ignition switch to the starter solenoid.

 

[nigelmercier]

I have no more than a rough idea what sort of current the cable has to carry ...

Sizing cables has more to do with acceptable voltage drop than the current capacity of the cable. What size alternator and battery bank? Do you have a smart regulator with a remote sensor? Blocking diodes, VSR, or switch?

 

[srp]

The alternator is not original - a Delco Remy with no markings to indicate model number, and possibly came from a Vauxhall Cavalier. There is a single battery, 110 Ah and no smart regulators, blocking diodes etc of any sort. (It's the Nelson 18 launch in my avatar, not a saily boat).
The panel is mounted at the back of the engine, so cable runs are limited to about 1m in length so voltage drop is not going to be that much of a problem.
The starter solenoid is also not original but has no markings on it. The thermo-start is probably an original part and I have seen the same on other Perkins engines.
The main battery pos and neg cables are 40mm2 as far as I can judge from their od, and are reasonably new - I 'm not planning on replacing them as they seem to be the only wiring that has been done properly - the rest of the existing engine wiring consists of non-tinned wire loosely draped around the engine, spiral wrapped where they touch, and with dubious connectors badly crimped, most of them loose on the spades, hence the need to sort it out.