bonesbrakr is on to something here.

As stated earlier, figure out why the manifold is so hot.
Its not the starters fault of the excess heat issues.

A plugged CAT will show those 600* temps also.
Back in the day, those Cats would start a ground fire. Hence the warning label on the sunvisor of new cars.

 

Take a reading before and after cat…

 

A plugged catalytic converter will make the engine run HOT. Your reading with a infrared thermometer is a smart way to track down issues.

Our 1968 C3 has a 427 L88 "Clone" engine and with the 12.25-1 compression the factory starter was not strong enough whenever it got hot. I swapped it out for a Mini Gear drive starter with the potential to turn over engine with up to 18-1 compression so my engine was a breeze. The mini starter was the solution but it was still working hard.

Then I spoke to a MSD person about my ignition system and I brought up the Hot starting issue and how the mini starter was working fine. The guy at MSD suggested I try one of their Digital Retard boxes which would allow me to crank faster and start easier. With the MSD Box I was able to pull the ignition timing back ONLY while cranking. It would allow you to pull up to 20* of timing and then return the timing back to the MSD box. This20* timing pullback allowed the engine to crank faster unloaded from the ignition system. At ~800 rpm the timing goes right back to normal and the engine is running smoothly. It also has four retard circuits that can pull the timing back if I am running cheaper gas or experience any detonation.

With the ability of being a great way of assisting an engine during starting MSD put the feature in their newest 6AL boxes. This feature is built into my Holley Stealth Sniper and allows me to get rid of the extra parts on the engine. I just wanted you to know that there are other options to assist an engine to start. Pulling timing was a secret that is out and it really helps cranking the engine and starting it up quickly.

 

Great feedback everyone. More investigating to do! Did a test run this morning with the IR thermometer in the glove compartment. Unfortunately before I got the cat info and interpon's recommendation to check temps before and after. Going up the winding mountain road went good and at the end point after 30-45 minutes the car started right away again. Temps at manifold between 600-650, at exhaust bend around 380F (with heat wrap, that doesn't seem to do much as temp just past that wrap were similar) and starter at about 170-180F. No starting issues. Downhill was another story. Got stuck behind traffic somewhat and by then it was midday and temps about 85F. Back in garage car wouldn't start again. Manifold and 'bend' temperatures were similar as earlier after uphill, but starter now at 205F.

Too bad, will have to do another test run up the mountain to measure the before/after cat temps (15 miles, from 200 to 1850ft elevation, 30-50mph, T-roof off), park it in front of the cafe with views of an 11th century castle town and have a cappuccino and croissant (or two) while waiting for the car to cool down. It's a terrible business, this troubleshooting .

 

Hi All, just to put a close yo this issue: I ended up purchasing as starter motor from Quality Power in Yucaipa, CA. It was a very straight forwards swapout and good support from the guys there. The car has been starting flawlessly ever since on the very few times I was able to take it out since then. Today was my big heat soak test, taking the car up the mountain in 95F heat. Started just fine when I got to the top. I'll still have to follow up on all the other great suggestions, but for now I'm happy to have a car that starts when I want it to, not when it it pleases the car . Thanks everyone for your help.

 

What starter did you buy?

 

I bought their in 6562N. at USDc125.00 + shipping. The guys were great at helping me identify the right one for My L-82 Pace Car. Old one popped right off, new one right in. As 'plug and play' as it comes the bracket that supported the old one at the back is no longer needed with this smaller and lighter one. See comparison of the two motors in photo attached.