Here's another possibility, the new battery that came with the car looks kind of small. I know they're getting more efficient, but this one says 640 CCA on it.
Would that be enough power to crank a hot 455 with 200 pounds compression?
Just one more link in the chain.

 

That battery should be adequate to start the car but likely does not have much reserve starting power.. Make sure you do not have any other draws on the battery while it is cranking. A higher rated CCA battery is a good investment though.

Dave

 

If the starter and or its cables are not in top notch condition it will not help the increased demand when hot. Make sure all the connections are clean and tight. Have the starter bench tested. Purchase a starter heat shield and wrap the header or head pipe with an exhaust blanket. I don't recommend wrapping the starter with a blanket. Also invest in a truck spec solenoid and spring for the high torque GM style starter. Do you have a high torque starter on the 455? You should. Note even a cable that visually inspects good may have to much resistance. Check with an Ohm meter. I always run at least a 750-775 CCA battery. If I can find a 8 or 900 in that group I will use that too.

 

I think that battery cca is the minimum you would want. in the past i have added 10 amps with a charger attached to see how it cranks...that can help diagnose it if it starts right up with the charge

 

Well, I've ruled out one more thing.....battery. I forgot I had a good 875 CCA battery sitting on the bench. I've been charging it frequently, but it didn't used to fit the stock cable. With the newer, longer cable, it fits now. No difference. Still doesn't turn over for a few minutes when hot.

Now I've ruled out battery and timing as possible culprits. Next I'll look at
a) The two cables and their various connections
b) The starter, both condition and heat issues.

I don't have a high-torque starter, but I may get one eventually. Just didn't like the sound of $290 at the local Lordco. Was thinking of ordering one from the US in to Point Roberts, but the Canadian dollar is so low right now. I've been told they don't heat up as much, being a bit smaller.

 

Have you checked the connections at the starter. Make sure the cable end is good and most importantly the purple wire and the terminal that's on the end. If all that is good, I would drop the starter and go though it. It's not that expensive to rebuild your stock starter and replace the solenoid.

 

I was thinking the solenoid would be okay since it starts to turn, but it's really slow. Sometimes not turn at all until it cools a bit.
I called to talk with my electrical guy today, but was told he was off sick. Might not be back until next week. Bummer.

Oh well, lots of retired people to have coffee with until then. Actually, many more jobs to still be done on the car. No shortage of fixings required.

 

I love the mini starters. They just plain work.

 

Ya know... its probably been 30+ years ago but I'm pretty sure that was the same symptoms on my 1971. Cranked really slow when hot, but cranked fine when cold. I put on the Summit kit I mentioned on the other thread. That kit has a Ford starter solenoid in it and a jumper between the small posts on the GM starter solenoid. That fixed my problem and the kit is only about $20.


John

 

That's a really cheap fix. Good for you.

 

It's even cheaper if you just buy a Ford solenoid. I have one on my car because I installed a mini starter, and have no problems. However, never had any problems with a stock setup either.

 

I'll discuss all these ideas with the electrical guy when he returns. Hope I get it fixed before I buy another car, or I'll forget all over again.

 

HonestDave, I had the same issues until lately-I have a good 4-field GM starter-no mini. I made a new 0 gauge ground wire from the battery bolted to the drivers side head. Made a new 0 gauge positive wire to the horn relay. Wrapped the wires from the starter up past the headers. My 455 has a consistent 215 psi in each cylinder, 10.5 compression.This does not have anything to do with your issues but alot of folks forget to run a good ground from the back of the passenger side head to the firewall. GM used a braided copper piece which I use. That is the ground for your dash and lights. No more issues. (at least with that)

 

I might try that, thanks. I checked with the muffler guy yesterday, and he said most of the big block A body fellows are running mini-starters now. Your way sounds less expensive.
I also looked yesterday, and the header pipe at the forward end is actually touching the starter.

 

I have a mini-starter on the 64 F-85. On my 67 A-body you could barely get a piece of paper between a header tube and the starter. The other issue running headers with the GM starter is you have to unbolt the header, remove the engine mount bolt and lift the engine a little to get the starter out.

 

The Ferd solenoid works, but not for the reason most people think. There's a much easier and less invasive method, as described in this thread, starting at post number 12.

 

The relay is all well and good for the stock starter. However the problem is when you don't have the bypass wire provision running a mini starter and points or coil B+ in the start position older cars. Then you have to get double pole little relay.

I like the idea of not having voltage to the big lug on the starter at all times with headers, which is why I run the Ford solenoid. I also did some other mods to my ignition to include a small relay for HEI power. Personal preference on which direction one wants to go.