Slow Cranking, won't start after warm up

[69_Vertibird]

I have a 1971 Lemans with a Mild Chevy 350, including ceramic coated headers, 11:1 compression, etc. Car starts fine and runs. Drive it around for a while and it won't hardly crank. Not enough cranking speed for the engine to fire. Then it floods the plugs with gas.

Thinking it was a typical Chevy hot start problem, I put a heat shield on the solenoid, didn't fix it...then I put a Ford solenoid on the inner fender...still didn't fix it. Now what?

Could the starter motor be bad? It was a reman starter that came with the RTR motor. Does header heat affect the starter motor as well as the solenoid?

Another person suggested the battery cable needed to be bigger gauge...like welding wire, with more strands because of the long distance from the opposite side of the motor to the Chevy starter. If that were the case wouldn't it be a problem all the time, and not just on restarts?

Help me with the cure, so I can drive and not be "stranded", literally!

Thanks,
Bill

[george kujanski]

Your fixes would only help if the solenoid would not pull in at higher temps. The fixes will not improve a slow cranking starter.

Hot starters have less torque because the motor windings have higher resistance, limiting the current from the battery. Smallish cabling and poor connections make the issue worse.

A hot engine is harder to crank than a cooler one (at least at reasonable ambient temps). Along with 11:1 compression slower cranking is not surprising.

Improving your cable size and connections (ground and battery positive) may help, along with a battery with higher CCA rating.

Was it always like this or has it deteriorated? The latter may indicate starter wear.

George

[69_Vertibird]

It's a "new" motor...I've only had it in a couple of weeks, but it's always been like this. It's a reman starter. I read something yesterday on the http://www.PartsAmerica.com web site that cranking with less than 9 volts will damage the starter motor. What is that about?

So...does that mean start with the cabling, then the starter motor? One person suggested measuring the voltage at the battery vs. at the starter. Does that work to assess the cabling?

Is there a way to "load test" a starter to duplicate the high heat situation, outside of the motor?

Thanks for the reply,
Bill

[george kujanski]

Cranking at lower voltage would cause slow cranking which draws more current, which heats up the starter, which reduces torque, which causes slower cranking..........

You don't really have control of the cranking voltage aside from making sure the battery cables and connections are good.

I would put in larger cabling, will never hurt. Assuming you have a high CCA battery, if you still have slow crank issues, I would just go to a "mini starter' as sold by Summit, jegs, etc.

These are reduction gear starters, and rather than mess around with your reman, they will crank your high compression engine more easily.

I'll be passing thru Jeff city in a few weeks on my way to lake of the Ozarks for some boating fun. I'll wave as I go thru.....

george

[69_Vertibird]

Thanks George,

I put new cables on when I dropped the motor in, but will consider going to the welding wire as my friend suggested, but it sounds like I need to invest in a really good starter that can handle the heat.

BTW, when you go to Lake of the Ozarks, take some time on Fri or Sat evening to go down to the Bagnall Dam area any time from 7p-Midnight...lots of cruising--old cars, imports, pickups, grandma's wagon, etc...lots of people...families and kids...and a rather popular sport that involves Mardi Gra Beads and video cameras ;-)

Happy Boating,

Bill

[george kujanski]

They do the bead thing at Bagnell Dam??????????

"Really, Hon, I'm just going to use the batting cage for awhile.....the camera is just to document my swing"

George

[Jeffzilla]

I have a 383 stroker motor that is 11.4 to 1 compression and it broke a stock starter, had to go with an aftermarket high torgue starter, no problems since.

[69_Vertibird]

I have fixed the problem. The resolution occured after I fixed two things, 1) a faulty ground from the battery -- bolted in a hurry to get the car started to the aluminum intake instead of the block - aluminum is not a good conductor of electricity, and 2) replaced the "stock" battery cables with higher grade, small strand, 2 gauge battery cables. No further problems since.

[george kujanski]

Actually, aluminum is a good conductor of electricity.

Connecting the bat neg cable to the cast iron head or block ia better connection because the starter ground return is thru the starter to engine mount.

The larger cables undoubtebly helped out also.

george