Starter heat soak

[1974scamp]

Hi at all,

I read a lot to the topic but i just cant get it working.

To my setup:
Its a 1974 Plymouth Scamp with a LA 408 stroker and full length Hooker headers.
The headers are wrapped under the starter and the tube which goes over the steering is wrapped in the starter area.
First i had a no name mini starter (which worked with my old headers who were fully wrapped) but heat soaking after a short drive.

Then I bought another mini starter from rockauto also really cheap still heat soaking.
Tried a starter heat wrap + a selfmade aluminium heat shield which covers the left side and the underneath of the starter.
Still not working when the car was running for a while.

Now i just got a powermaster 9300 starter, wrapped it in tin foil (read that somewhere here in the forum) + the starter wrap + the selfmade aluminium heat shield. Still not working when hot.

Cables are all new, + directly from the battery in the trunk to the starter with a massive cable, starter relay new, optima yellow top battery with over 12.5V,
timing was an 12 initial but now i put it to about 17 initial and the headers are a lot cooler after this, but still the starter turns only really slow or barely when the car is hot and it wont start up.

I dont want the wrap the headers full,
any other suggestions??

Thank you all,
Laurin

 

[MOPAROFFICIAL]

how good is the ground wire from the battery ? ground the engine to the frame real good?

you shouldn't have any heat soak, you probably have a lack of amperage with that long-*** power wire coming from the back of the car, what gauge is it?

 

[67Dart273]

All right "massive cable" does not tell me much. Your idea of "massive" and mine might be different

Detail the path from battery to starter. Is there a disconnect? Second solenoid?

What is the ground path EXACTLY. Might be as simple as a poor ground between engine/ body/ battery.

Before you do anything, and after the car as sat awhile (to bleed off surface charge) measure battery terminal voltage and post it here. Maybe? the battery is down

Clip your meter to the starter big main terminal on the solenoid, and to a good engine ground. Crank the engine and read the meter. No disconnect the coil wire and ground it and check it again..........starter may be "kicking" on the starter. You need "accepted" minimum of 10.5V and anything below 10V is just not gonna fly

 

[1974scamp]

All right "massive cable" does not tell me much. Your idea of "massive" and mine might be different

Detail the path from battery to starter. Is there a disconnect? Second solenoid?

What is the ground path EXACTLY. Might be as simple as a poor ground between engine/ body/ battery.

Before you do anything, and after the car as sat awhile (to bleed off surface charge) measure battery terminal voltage and post it here. Maybe? the battery is down

Clip your meter to the starter big main terminal on the solenoid, and to a good engine ground. Crank the engine and read the meter. No disconnect the coil wire and ground it and check it again..........starter may be "kicking" on the starter. You need "accepted" minimum of 10.5V and anything below 10V is just not gonna fly

Thanks for the fast answers!
The battery is not the problem as i tried it already with another bigget one.

The cable coming from the battery to the front is 50mm2 (about 0 gauge) then splits into two 35mm2 (about 2 gauge) - one goes directly to the starter and the other goes to the big bolt of the starter relay.

I just looked at the ground cable from the battery to the frame in the trunk and the ground cable from the engine to the firewall, they seem fine and thick enough i think about 2 gauge aswell.
But I will double check that tomorrow by putting the bigger battery with starter cables + directly to the starter and the - directly on the block.

I will do the volt checks aswell and will let you know!

Thanks, Laurin

 

[kursplat]

if the electrical checks out, try ducting a little fresh air
example:

 

[tonysrt]

Have you had this problem from a recent change of something? I had a rebuilt 440 and full headers and had heat soak starter problems till I had some miles on the motor. I then removed the headers and went to Hi po exhaust manifolds and problem went away for good. I then put a gen2 hemi in the car and went with repro exhaust manifolds and never had a heat soak problem with them. I don't race so I give up the 20-30 HP loss with the manifolds but have other benefits, long lasting less heat and noise.

 

[AJ/FormS]

I had that problem on my 367.
I ended up taking the engine out and regapping the rings looser and added some skirt clearance, Shazzam,now she winds over like a champ. Daymm that was annoying.

 

[1974scamp]

All right "massive cable" does not tell me much. Your idea of "massive" and mine might be different

Detail the path from battery to starter. Is there a disconnect? Second solenoid?

What is the ground path EXACTLY. Might be as simple as a poor ground between engine/ body/ battery.

Before you do anything, and after the car as sat awhile (to bleed off surface charge) measure battery terminal voltage and post it here. Maybe? the battery is down

Clip your meter to the starter big main terminal on the solenoid, and to a good engine ground. Crank the engine and read the meter. No disconnect the coil wire and ground it and check it again..........starter may be "kicking" on the starter. You need "accepted" minimum of 10.5V and anything below 10V is just not gonna fly

Just did the tests:
When the car is hot and while cranking i have about 7v its hard to read as it jumps around but never over 10v while cranking.
Tried with 2 different batteries and put the battery with cables directly on the engine block and big bolt of the starter relay.

What can be the reason for that? Dont believe that both batteries are ****.

 

[1974scamp]

I had that problem on my 367.
I ended up taking the engine out and regapping the rings looser and added some skirt clearance, Shazzam,now she winds over like a champ. Daymm that was annoying.

Thats my biggest fear at the moment, the engine is really hard to turn over by hand when warm but will compare again when it cools down.

 

[AJ/FormS]

Assuming the electrical system is adequate;
The voltage may be dropping so low because the starter is working so hard. All that energy is going to magnetism and heat, because the starter cannot spin.
I would repeat the HOT-test with the spark plugs out, to see how much of the work is to overcome compression.
After that, if still low, I guess I would back off the rocker gear, to eliminate the spring-pressure.
At this time, all you got left is pistons and rings, plus whatever is attached to the crank.
If the voltage is still low, sub in a different starter, charge the battery and start over.
That's how I diagnosed mine.
BTW, my Optima Battery doesn't seem to have a lot of Rest-voltage, but it does seem to crank very well at 10/10.5 under load. I had to get used to that.
On mine;I don't know if the tightness was skirts or rings. There was no evidence on the skirts, but I figured a half a thou couldn't hurt.Actually, I think I might have gone a full thou, that was year 2000. I didn't keep notes,lol.
But I opened up the gap a lot. The KB-recommended gap-factor on my KB107s was .0065 Which comes to gaps of .026. I went with their towing factor of .008, which comes to .032. I installed Plasma-Moly file-fits, and that was the end of my problems. So after that, I increased my Thermostat to 180 then 195, and finally, she now runs 205 measured at the hottest part if the stathouse. Still no problems; click-vroom/vroom.