I have a 68 big block/427. After the car has been running for awhile , when I stop car , and try to restart, it cranks over so slow. However after the car has sat for awhile and cooled down starts up right away. I have shielded the starter from the engine, and even replaced the starter, NO change. I have a friend who mentioned that these new style hi torgue starters can take the heat, and work well with this situation. Any idieas ?

 
Chances are the problem is with the solenoid, and not the starter itself.....assuming there is a problem with the starter at all. Is the engine running hotter than "normal"? Does it "ping" when under a light load(cruizing speed)?
If the ignition timing is too far advanced, you'll get this exact same problem when trying to start a hot engine. One method to determine if it is a timing issue, or starter issue is to try this.....
Next time it cranks slowly, pump the crap out of the throttle 4-5 times, then try to start it. If it starts then, you have a timing issue. The massive volume of raw fuel in the intake will COOL the combustion chambers, and allow the engine to crank properly. It may sound crude, or like an old wives' tale, but it works.
If it doesn't do any good, then you have a heat soak issue with the starter/solenoid. If you are not concerned with keeping the car 100% original, you can install a....ahem...FORD starter solenoid on the firewall/fenderwell area, do a little simple re-wiring at the GM solenoid, and eliminate the heat soak issue for good.

Thank you for responding. I have tried the pumping gas, no good. Also have purchased a new starter with the same results as the old one was. The car is a hot running big block but not more than the norm. Have you heard anything about these new hi-torqe starters?

High torque starters are great. Smaller to begin with,so that helps get them a little further away from the exhaust heat.
They sometimes are a pita to get set up properly, since they are designed to bolt up to several different engine/flywheel combos. Other than that, they seem to be the cat's meow for a lot of folks. Several guys here have used them.

Back in the day(hunnert years ago), we were always having the same problem with starter heat issues on the race cars. Then we learned the trick about using the Ford solenoid.....NEVER had another hot start problem after that. Of course, there were none of these fancy schmancy high torques starters out there at the time.....

I've had a mini starter in my BB 68 vet & my 67 Dodge for many years now...no problems and had the same problems you are experiencing.  I would also check  or just replace the battery cables.  The red one will corrode over time. They tend to go bad over the years & don't allow enough current to flow especially under hot conditions. This is a common GM problem in the 60's & 70's.  Make sure your grounds from the battery to the frame & the ground to the engine & starter are good & clean. Putting 2  7" spal fans on the frame just behind the frt tires really helps to suck the heat out of theses BB cars.

Had the same problem with my 74 BB.  If I stopped the car on a hot day or after driving for a while, I knew I'd stay where ever I was for another 1 1/2hr until it cools down enough.  A bit of a pain when it's unexpected.  You learn to bring snacks & water just in case.

Otay...now ya got my attention! Alan, have you done this? Got any pics? Sounds like a neat mod!

I am not sure what you mean in a (mini starter) ?

 The "Mini" starters today are small in size, but big on torque. The old, "High Torque" GM starters are the same as the "normal" starters, but have a larger field winding. If you have a big block, it has a factory high torque starter on it....or at least it did originally. If it has been swapped sometime in the past, it may have a normal starter on it. You can tell a high torque GM starter by the length of the terminal on the solenoid that connects to the starter field winding. A high torque starter has a longer terminal, due to the connection being farther back on the starter body. I'll see if I can dig up a pic or two....



Here's a comparison of the Mini and stock starters....

Yes I did this mod many yrs ago right after I bought the 68. It had a 427 w/12.5-1 compression, 2.5 " headers going to a 4" collector, solid lifter & side pipes. It was used in racing & was way to mean for me, but it created a lot of heat so I figured out how to get rid of it..sorta like what Nascar does in there cars. I'll look for the link on my forum as I think it was about 10+ yrs ago. I rarely need them now, but on a real hot day it helps. I thought I posted it here too but I really don't remember.

|UPDATED|8/21/2014 4:50:29 AM (AZT)|/UPDATED|