Starter problem
 

I have a high compression IO540 (10:1) and a B&C starter (BCS206-149-12) which is barely able to turn the engine over and sometimes will not make it past the first compression point. This problem is not battery related but I wonder about the long aluminum cable that Van's provides to run from the rear battery to the firewall. Anyone else with this problem? Solutions?

The cable in my 10 was copper.

No trouble twisting the engine, 9.5 C/R

PC925 in the rear.

1st, remember that the problem can be on either the positive circuit, or the return (ground) path.

I would 'divide and conquer'. Start in the middle of the circuit (the starter terminal).

Have a helper hold the negative terminal of a volt meter directly on the battery negative post (not the terminal; the post coming out of the battery). Place the positive lead on the 'fat' terminal of the starter. (You'll obviously need to extend the leads to do those things.) With mixture at idle cutoff, and ignition off, if possible, clear the prop & hit the start button while monitoring the meter.

If the meter reads less than around 8 volts (or drops to near zero) *while the starter is trying to turn the engine*, you either have a battery problem or high resistance somewhere between battery + & starter.

If the meter reads near the full battery voltage *while the starter is trying to turn the engine*, you have a high resistance somewhere between the starter frame and the battery - terminal.

Again, divide and conquer.

Find a mid-point in the side of the circuit where you've seen the problem, and check again.

Remember, problems on the 'ground' side are just as common as on the positive side.

Remember that every transition (battery post to terminal, terminal to wire, wire to terminal, terminal to contactor post, across the contactor contacts, etc etc can be a failure point.

(A perfectly functioning system with healthy battery would show battery voltage *across the battery terminals* of between 8.5 and 10.5 volts *while the starter is turning*, and no more than a 1/2 to 1 volt lower than that, between the starter post and battery neg post.)

Charlie

I have had many cars and airplanes with the battery far from the starter, everyone jumps on the cable but it's not the problem. Check all connections. The wire is sized to avoid significant voltage drop due to resistance.