Alternator Question

Hello,
I am doing an engine swap, as part of this the alternator will be going in with the engine. The issue is that it is a 70 amp alternator,
and the car is more used to 34/43 amps.
Do I need to worry about anything other than increasing the size of the
wire from the alternator to the battery to handle the extra current ? or should I be making changes to the loom as well?
Thanks for any advice.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The alternator size does not matter, it's job is to provide current for the battery, which in turn runs all the electrics in the car. If you car only needed 30amps before, then it will only need 30 amps now, if you were to have say a kettle running in the car and a few subs and amps etc then yes you may need to up the wiring.
Current is drawn from the alternator it doesn't actually give anything unless it's needed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thank Ronny, it's actually a V8 with an electronic ignition going into an MGB. It's carbs, not EFI. So thats something. I'm assuming that with a beefier starter it will draw more current.
What bits of wiring should I be looking at ? just ignition/engine related?
Hmm, kettle eh?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Didn't realise you were doing a V8 lol, that would need some oompfh to get it started, so def use the above cables from the old car, but the rest of the wiring will be fine :)
Also you will need to upgrade the battery to provide the extra amps when cold, so try and get the one from the doner car.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Liam says...

GOOD MAN.
--
Conor

"You're not married, you haven't got a girlfriend and you've never seen
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Car loom will be fine unless you are adding extra equipment like higher wattage headlamp bulbs / extra lights etc etc, but that is irrelevant to the alternator.
With regard to the alternator, increase the gauge of the wire from alt to battery, AND check the engine earth strap from block to body and or to battery neg is also of sufficient capacity for at least the max output of the alternator.
Tim..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd hope the earth strap would be given it has to carry starter current. ;-)
--
*Support bacteria - they're the only culture some people have *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

to
of
Oh aye! *doh*
Brain wasnt engaged before fingers! lol
Tim..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No - simply uprate the output cable to the battery.
--
*If you try to fail and succeed, which have you done? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Leave the loom alone, the headlights and whatnot will draw the same current as before.
TBH, the "correct" solution is to use the wiring for the bigger engine, in terms of starter motor and wiring to the battery from the alternator, and the coil. This is correct for the engine. Similarly you should use the battery from the donor or one listed as suitable for that engine.
But on the other hand, if you don't have these bits available, use the old battery, old wiring. It'll work, most likely, and if it melts and starts a small fire you'll fix it the same way as you'd prevent it, i.e. buy a larger battery, fatter starter cable, etc. Might as well let it fail and avoid that cost if it doesn't.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hello All,
I still have the loom from the old car, and all the ignition bits and was planning to re-use them. It was just that I wasn't sure what effectit would have on the rest of the loom. But you have all cleared it up for me, thanks for your advice.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

From memory there's no difference in the starter motor cable gauge between an MGB and any Rover V-8 engined car. Indeed a later car might actually use thinner wire.
--
*I'm already visualizing the duct tape over your mouth

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.