Engine cranking too slow....

Dano65 · May 12, 2019

`I'm having a slow cranking problem on a fresh 540" big block motor I'm working on. It's 12.5:1 compression and has a Proform hi-torque mini starter on it but when I try to start it it cranks very slow then stops all together? It was running on a test stand so the motor itself isn't the problem. I did try another battery and it does the same thing. The battery is in the trunk and has either 0 or 2 gauge wire running to the starter and 2 gauge ground cable to the cage in the trunk. Solid motor and trans mount plus 2 ground straps from the block to the k-member and body so I doubt that's a problem. I took the starter in to have it checked and even though it spun fast, there's no way to check it under a load so I'm out of ideas on what to try next before spending money on another starter. Any electrical tests I can try first?

Thanks for any help!

MoparLeo · May 12, 2019

With the starter on the engine, jump the battery + and - cables directly to the starter. This eliminates any possibility of it being a ground problem. If it spins fast, it is not the starter, if not, it is.

Don Frelier · May 12, 2019

If you experience this when hot but ok cold then your timing is too far advanced

Dano65 · May 12, 2019

Will try the jumper test to see. Now to find cables.....
Does it cold so it's not a timing issue.

beanhead · May 12, 2019

Do MoparLeo's test first. Another check is to bring the battery close to the starter and connect it with shorter cables, it's possible with that compression and distance you need even bigger cables. We had this problem on a 12.5 to 1 chevy rat that also had the battery in the trunk...I think we ended up with 1/0 welding cable and that fixed it. (Of course it was a chevy with sorry chevy parts haha). Good luck it sounds like a beast..

Dano65 · May 12, 2019

beanhead said:
Do MoparLeo's test first. Another check is to bring the battery close to the starter and connect it with shorter cables, it's possible with that compression and distance you need even bigger cables. We had this problem on a 12.5 to 1 chevy rat that also had the battery in the trunk...I think we ended up with 1/0 welding cable and that fixed it. (Of course it was a chevy with sorry chevy parts haha). Good luck it sounds like a beast..

Going out there now to put the starter back in and try shorter cables. I'm dying to hear it run!

threewood · May 12, 2019

Is the positive cable end getting hot? If so, high resistance in the clamps, joints or cable.

Dano65 · May 12, 2019

threewood said:
Is the positive cable end getting hot? If so, high resistance in the clamps, joints or cable.

No, negative was getting warm back by the battery so I tried running 2 ground cables but that didn't help. Not hot though.

Dano65 · May 12, 2019

Well, I made a not too uncommon mistake and cracked the starter nose (oops) putting it back in so it looks like another starter is coming anyway. Found a almost brand new MSD Dyna Force starter on CL that I'm gonna probably pick up tomorrow so I guess I'll know for sure if it was the starter. Is there anywhere that sells just the nose in case that wasn't the problem?

Engine cranking too slow....

Dano65

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Don Frelier

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beanhead

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threewood

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