Starter motor

[steveslittlelucy]

Afternoon, I wonder if anyone can help,my sbc has always seemed slow turning over since I’ve had it and i wondered if the live wire was at fault ( the battery is in the boot) so this afternoon I replaced it but it’s no better, when I put a volt meter on the battery feed on the solenoid it was 12.4v but when I got the Mrs to crank it it only read 4.5v, does this mean I need to get the starter rebuilt or is it a power problem- I’ve tried 2 batteries that go up into the green on a drop tester and stay there and I’ve got 2 earths on the car and one of them comes off a starter motor bolt, any advice would be appreciated

Steve

[stueeee]

How big is the cable from the battery -you really need something bigger than the usual 12v size of 16 sq mm for a long run. Something like this should work OK. I would be inclined to run an earth cable in the same size direct to the starter too.
https://www.ebay.co.uk/itm/Copper-We...qAM1f2xFKWHN2A
25 sq mm cable is actually about 10mm diameter.

[steveslittlelucy]

How big is the cable from the battery -you really need something bigger than the usual 12v size of 16 sq mm for a long run. Something like this should work OK. I would be inclined to run an earth cable in the same size direct to the starter too.
https://www.ebay.co.uk/itm/Copper-We...qAM1f2xFKWHN2A
25 sq mm cable is actually about 10mm diameter.

Thanks for the reply, I bought some 21 mm 170amp wire off of eBay but I must admit It’s funny stuff , it doesn’t take solder that well, my father in law has some old arc welding wires that are quite long , I think I’ll do both like you suggested .
Steve

[timbo56]

It could be the solenoid is worn or not connecting properly or you have old cable and dirty connections. Mine was slow or wouldn't start when hot. I used 70mm 485 amp cable on my SBC plus I fitted a second solenoid with the switch wire jumped straight from the large starter cable connector.
70mm2 485 A Amps Flexible PVC Battery Welding Cable Black Red 1 - 100M M Lengths | eBay
As an after thought, is your switch wire wired correctly I.E. not running from a ballast resistor?

[steveslittlelucy]

It could be the solenoid is worn or not connecting properly or you have old cable and dirty connections. Mine was slow or wouldn't start when hot. I used 70mm 485 amp cable on my SBC plus I fitted a second solenoid with the switch wire jumped straight from the large starter cable connector.
70mm2 485 A Amps Flexible PVC Battery Welding Cable Black Red 1 - 100M M Lengths | eBay
As an after thought, is your switch wire wired correctly I.E. not running from a ballast resistor?

I think tomorrow I’m going to get it up on the lift and put 2 very short leads to the starter to see if it’ makes a difference before I go any further and if that works I’ll use some welding leads, the wire to the solenoid comes straight from the ignition , thanks for the advice
Steve

[timbo56]

I think tomorrow I’m going to get it up on the lift and put 2 very short leads to the starter to see if it’ makes a difference before I go any further and if that works I’ll use some welding leads, the wire to the solenoid comes straight from the ignition , thanks for the advice
Steve

While you're doing that you could try putting a direct feed from the battery to the switch terminal on the solenoid (so you're bypassing the ignition switch) with some new wire to see if that makes any difference.

[Mad Mark]

Mine was always slow, but slowly speeded up........ In the end I replaced the starter with a hi-torque unit that was £100 from Russ Pepper. perfect after that! ...and as a bonus I was able to turn the solenoid down away from the exhaust to stop the ole SBC heat soak problem I had had for ages!

[steveslittlelucy]

This afternoon I put 2 short leads straight to the starter with a remote starter button and it turned over a lot faster so I’ve made a new battery holder and put it back in the engine bay so hopefully it’s sorted now, thanks for everyone’s help.
Steve