I've been having intermittant problems with starting my BB for a while now when hot, i.e. heat soak, solenoid just clicking etc. but lately i've had a problem with reduced voltage to the solenoid on both the ignition terminal and the cranking terminal.
I just fitted a new battery last week but it is only putting out 550 cranking amps but i'm going to get a bigger one say 650 C/A as it was the only one i could get at the time
(My main question is what is a permissable voltage drop on the ignition terminal of the solenoid, and also on the cranking terminal,) at the moment i've got 0.3v drop on the ignition side and 1.75v drop on the cranking side. With the new battery in it the volts sometimes drop to 10.5v when turning the engine over and the rest of the system drops from there. Alternator is fine it's 100amp and is charging to at least 13.6v no matter what load is put on the system.
Any other points fell free to comment.
TIA.
Peter.

 

Just a few comments that may or not pertain to your setup. Does your starter have/need a heat shield? I put one on mine to keep the header pipes from cooking the starter. Regarding battery size, I'm currently running a 470 CCA battery (although I'm also using the later C4 gear rduction starter). My next battery will be 390-430 CCA to reduce the battery weight again.
Regarding the voltage drops you've seen, while I can't say I've ever actually measured these points, they don't look outrageous. Given the great amperage that the starter will draw under load, it only takes a very small resistance to add up to a volt or two. What do your battery and starter terminals look like?
Like I said, these are just my thoughts. Let us know what you end up finding out. Good luck.

 

Having a BB i'm not really worried about extra weight as the engine is enough weight on it's own and seeing as i've lost three stone in the last four months i've had a good weight reduction there
But jokes aside i haven't got a heat sheild at the moment but did use one a few years ago with no real benefit to starting when hot, apart from when i fitted a new solenoid a few years ago. As far as the terminals go they are all in good condition and all of the wires to the started have been renewed to where they dissapeared into the firewall.
Any BB owners got any thoughts. I know i can go down the route of a mini starter but was wondering if the wiring is at fault somewhere else in the circuit.
Thanks
Peter

 

Providing that the battery and cables, including ground cables/contacts, are good, the solenoid and heat soak are often blamed needlessly when the real problem is a deterioration of the connectors in the wiring to the crank (S) terminal of the solenoid. Track the wires from distribution to the ignition switch, to the connector under the rug, through the neutral safety switch, through the engine wiring harness to the S terminal on the solenoid.

A good way to tell if this is the problem is to jump from the battery terminal to the S terminal when it won't crank. (With a BB, you may not be able to do this, and may have to wire in a jumper wire and starter switch as noted below.) If it cranks, look for a problem as noted above.

Before I discovered the real cause in my car, which was a partially melted connector beneath the carpet, I wired in an auxiliary engine bay starter switch on the firewall between the battery cable stud on the solenoid to the S terminal, using 12 gauge wire. Whenever I found that the engine would not crank (usually a hot restart), this starter switch worked great meaning that the problem was excessive voltage drop in the stock circuit to the crank (S) terminal itself. An then afterward, with the knowledge that the starter and solenoid were good, I discovered the real cause of the problem.

 

Regarding your battery, 550 cranking amps is ample for your car. It takes considerably less than that to start a car.

 

I had the same starting problems on my '70 small block. Got a $85 Interstate battery with 850 CA and 650 CCA cold cranking amps - never a problem after that. Stock starter. And, of course, if the engine is tuned up you shouldn't have any problems. Not to insult you but be sure the connections at the battery are tight - use a flashlite to make sure. Take care. Peter

 

I was thinking of doing this myself, but just wondered if anyone had any figures for what sort of voltage drop is the normally found in a system in good condition with a good battery.
Thanks for your input and i might have to go down that route of tracing the wire but i'm not looking forward to it as i've just had my interiour refinished, and all the carpet & underlay has been stuck down.

Peter

 

Sorry if I didn't answer the question directly, but if I measured more than 1/2 volt difference from the positive terminal of the battery to the S terminal of the solenoid while cranking, I'd really start looking at that circuit.

 

Cheers thanks for your answers.
Peter