Slow Cranking when hot

[RJS]

OK 72 B-Body 512 stroker, been having this issue for appro. 3-4 years and in turn this doesn't allow me to put enough timing (initial or locking dist.) in to help get a nicer idle. The cam is 245 @ .050 compression is 10.5 with aluminum heads. TTI 1 7/8" coated headers and exhaust, car never runs hot. Normal temps for this car are 175-185 area at most.

Slow crank when hot what to check first and how/why??? This has been like 3+ year thing. Different batteries ,solenoid, starters, checked grounds with meter, measured 12.9 at battery post on starter also, so is the next thing while cranking HOT I have to measure battery post and or starter post??? My cables are restoration style purchased 10 years ago when car was put together. Does someone make a restoration style cable that is actually much better now a days? Would a less chance of getting burned a good idea to make up a 10g wire with eyes to also go from battery cable post to starter post???
Thank Ron

 

[pnora]

What starter?

 

[RJS]

Oops forgot to say, I have had 2 different new dakota starters and just installed a Power Master XS last week which cranks faster so I tryed locking the distributor and it went to slow crank when hot. I now have distributor back to unlocked with 20 initial and it will tolerate that.

Ron

 

[RJS]

I'm going to make up the additional wire from battery post to starter stud to help positive wire because I can do this cold and see what happens when hot . Working alone sucks when doing stuff like this.

Ron

 

[Rick@Laysons]

Just my 2 cents worth......cuz I'm old and been right where you are.....

First thing I'd be lookin at is that "restoration" style battery cable.

Big cubes, advanced timing, modern hi-amp batteries, and heat soaked starters.....when trying to hot start, that "restoration" cable is pulling way more amps thru it than it was designed for.

You need a heavier gauge cable with high quality ends.

 

[PurpleBeeper]

OK 72 B-Body 512 stroker, been having this issue for appro. 3-4 years and in turn this doesn't allow me to put enough timing (initial or locking dist.) in to help get a nicer idle. The cam is 245 @ .050 compression is 10.5 with aluminum heads. TTI 1 7/8" coated headers and exhaust, car never runs hot. Normal temps for this car are 175-185 area at most.

Slow crank when hot what to check first and how/why??? This has been like 3+ year thing. Different batteries ,solenoid, starters, checked grounds with meter, measured 12.9 at battery post on starter also, so is the next thing while cranking HOT I have to measure battery post and or starter post??? My cables are restoration style purchased 10 years ago when car was put together. Does someone make a restoration style cable that is actually much better now a days? Would a less chance of getting burned a good idea to make up a 10g wire with eyes to also go from battery cable post to starter post???
Thank Ron

Your stater(s) are getting hot. Electrical resistance goes up with heat. Try header wrap & wrapping the stater in heat shield also. Additionally, you could add a timing retard while cranking. A MSD multiple retard box does this

 

[Bird 426]

Do you have a shield or heat blanket at the starter? Have you tried spinning the engine over when hot with the ignition disconnected? If so, does it still turn over with difficulty? It may be cable related as has been suggested.

 

[R413]

The best starter is only as good as the cables. Go buy some bigger aftermarket battery cables to try as a test to see if that's the problem. Do Both cables the pos and neg need to flow the same amperage.

You have changed everything but the cables.

 

[RemCharger]

See if the cables are hot.

 

[BSB67]

What is your cranking cylinder pressure?
What is your initial timing?
What starter(s) are you using?