General Build Advice Needed

[Guest mcramsay]

Righty, I have been scratching my head for a few days trying to figure out where I am going to place parts on my marlin, the main issue being the battery position, the main problem I have is the m3 engine I am using has a self contained engine wiring loom, this includes the starter motor cable. And it's all neatly routed around the engine, with one 12" length of 25mm cable which connects to the battery and supplies power to the loom and starter. The problem with this is the battery position, I was going to put the battery in the boot and run a cable to a 300 amp terminal box to connect my battery cable up the starter cable on the bmw loom, but I tried it today and I don't like it: this pic shows the bmw starter wire connected into the terminal box

 

I am now thinking that I would be better putting the battery within reach of the bmw cable, I'm going to use a oddesy pc680 which are pretty small, the only issue with this is the battery will be within 200mm of the swirl pot, which is not a great issue as I will box the battery in and have terminal covers on.

The benefits with doing it this way are I don't have 5m of battery cable from the front to the rear of the car, and the install will look more tidy. And give better boot space. The problem is the battery would take up space I wanted for the header tank on the cooling system. So I may have to look for an alternative position for the header tank, what are the basics for selecting a location? Has it got to be above a certain point?

 

So at the moment I have chosen the battery to go on the left hand side of this engine bay compartment

 

 

And hopefully fit the header tank smack bang between the battery and swirl pot, seem like an idea that will work?

[kevin the chicken]

I have recently had similar issues with space and header tank placement and in the end had to put the header tank in the only place available after deciding that as long as the water level in it was higher than the radiator water level it would work okay. Thankfully it does perfectly but if I was to start my time with this car again then the battery would be moved to the boot

[agent_zed]

battery in the boot of my bmw 316 so can't see it would be a problem.

[Guest mcramsay]

Thing is I'm trying to get away from having the battery in the boot, I think with the battery I have selected I will be ok. I can even mount the battery lying down, so would still have room above it for a header tank.

[Snapperpaul]

Header tank water level should higher than water level in the head

Most 7'ns have radiator lower than head thus a header tank needed