71 351 Cleveland starting/cranking issue

351mach1 · Dec 3, 2024

Good work getting it running! What ended up being the issue?

FirstMach1 · Dec 3, 2024

Well….thats a really good question. It’s still a bit of a mystery to me but here’s my best guess.
Compression along with possibly lack of lubricants from sitting caused resistance in the crank. I continually had to charge the battery after each attempt at slow cranking.
Eventually when the system got primed and lubed after timing was set roughly it just fired off.
I’m sure I’m missing something in there or could be wrong altogether. I don’t know if it’s still cranking slowly or not because it starts so quickly now.
I may disconnect the coil just to see if the problem still exists. Because if it does and someday it wont start right away, I’ll only have one or two chances for it to start and not be stranded.

Again, I really appreciate all the input. Even the suggestions that were circling the issue got me thinking in the right directions.

basstrix · Dec 3, 2024

FirstMach1 said:
It’s running again! All the stars aligned and we’re back in business. Now I can get down to the fun and easy stuff again like timing and fluid changes.
Thanks for all the input as it was invaluable and I learned so much during this mechanical adventure.

What was causing the slow cranking?

FirstMach1 · Dec 3, 2024

basstrix said:
What was causing the slow cranking?

If you read above I’m not sure. Still don’t know.
It’ll start right up now (timing not set yet) and run smoothly. However, after warming up today it went immediately back to a no crank issue.
Then it cooled down and cranked just fine. I’m clueless but still investigating.

Sheriff41 · Dec 3, 2024

FirstMach1 said:
If you read above I’m not sure. Still don’t know.
It’ll start right up now (timing not set yet) and run smoothly. However, after warming up today it went immediately back to a no crank issue.
Then it cooled down and cranked just fine. I’m clueless but still investigating.

Sounds like your starter is going bad. Pretty classic indications. Do have headers on your Mach?

FirstMach1 · Dec 3, 2024

Starter may be bad. But it’s only a couple years old and very little use. But still possible.
No headers

FirstMach1 · Dec 3, 2024

I had the starter tested a few weeks ago and it passed.

Sheriff41 · Dec 3, 2024

You could check how many amps your starter is pulling on a cold start, then check it on a hot start. Starter should draw less than 300 amps. Also check the CCA of you battery.

FirstMach1 · Dec 3, 2024

Sheriff41 said:
You could check how many amps your starter is pulling on a cold start, then check it on a hot start. Starter should draw less than 300 amps. Also check the CCA of you battery.

Thanks. Good idea. I’ll do that.

AcesArneson · Dec 4, 2024

I know you said the battery checked out at the shop but I would put my money there if I was betting. Did you pull the caps off the battery and check that the acid level is to the top of the bottom lip inside the hole, should be approximately 3/4” from the top of the battery. The battery could check the out at 12.3V ok but not hold a charge. If the level is low you can get the battery checked to see if it’s distilled water you need or battery acid.

Tnfastbk · Dec 5, 2024

Sounds to me like too much timing if it will start cold but not when it hot (up to temperature).

AcesArneson · Dec 5, 2024

Tnfastbk said:
Sounds to me like too much timing if it will start cold but not when it hot (up to temperature).

Did he say it would not run or was it just hard to start?

Tnfastbk · Dec 5, 2024

AcesArneson said:
Did he say it would not run or was it just hard to start?

this was from one of his posts above:

It’ll start right up now (timing not set yet) and run smoothly. However, after warming up today it went immediately back to a no crank issue.
Then it cooled down and cranked just fine. I’m clueless but still investigating.

AcesArneson · Dec 5, 2024

Tnfastbk said:
this was from one of his posts above:

It’ll start right up now (timing not set yet) and run smoothly. However, after warming up today it went immediately back to a no crank issue.
Then it cooled down and cranked just fine. I’m clueless but still investigating.

Yeah, so it doesn’t look like it is not running, just looks like when he attempts a restart after the engine is warm it is hard to start because it cranks over too slow. Do you have another battery around you could stick in there and try out to confirm if the battery holds charge? I have had a shop tell me a battery is fine and it starts to discharge as soon as it is charged or doesn’t have enough acid to hold the charge.

FirstMach1 · Dec 5, 2024

AcesArneson said:
I know you said the battery checked out at the shop but I would put my money there if I was betting. Did you pull the caps off the battery and check that the acid level is to the top of the bottom lip inside the hole, should be approximately 3/4” from the top of the battery. The battery could check the out at 12.3V ok but not hold a charge. If the level is low you can get the battery checked to see if it’s distilled water you need or battery acid.

Yes. Battery is good

FirstMach1 · Dec 5, 2024

FirstMach1 said:
Yes. Battery is good

I’m going to double check everything again. Battery is 8 mo old. Starter is just over 1 year old. I’m leaning towards the starter again even though it was checked out. Under warranty so easy switch.
Nothing else seems apparent. Got timing set and tuned carb now. Ran beautifully for 20 minutes or more. Then I shut it off and slow cranking resumed. Started again after it cooled.
I don’t have anything to check the amp draws on the starter so I’m gonna swap it and see what happens. Gotta love this China crap

Cleveland Crush · Dec 5, 2024

@FirstMach1; carefully inspect the starter cable condition, it's contacts and battery ground connections.

FirstMach1 · Dec 5, 2024

FirstMach1 said:
Yes. Battery is good

I’m going to double check everything again. Battery is 8 mo old. Starter is just over 1 year old. I’m leaning towards the starter again even though it was checked out. Under warranty so easy switch.
Nothing else seems apparent. Got timing set and tuned carb now. Ran beautifully for 20 minutes or more. Then I shut it off and slow cranking resumed. Started again after it cooled.
I don’t have anything to check the amp draws on the starter so I’m gonna swap it and see what happens. Gotta love this China crap

Cleveland Crush said:
@FirstMach1; carefully inspect the starter cable condition, its contacts and battery ground connections.

yup. All good. New cables too

FirstMach1 · Dec 5, 2024

I just had the starter tested again. It passed again. However this time the tech was savy enough of a mechanic that he could tell by the sound and play in the shaft that it was bad.
Free replacement going in tomorrow and I’ll let you know.

Spaceman · Dec 6, 2024

How slow are we talking? I used to think I had a problem because my 70 was slow cranking when the engine was warm. That's just a common problem with an unshielded starter from excess heat.

It's also possible your car is allergic to vanilla ice cream.

71 351 Cleveland starting/cranking issue

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