Slow turn over

Gufshoz

Gufshoz

Member
I have an interesting issue. Twice, when I’ve stopped to refuel, the engine barely turns over to restart It’s fine when cold, or on an immediate restart. This has only happened when she’s off for about 15 minutes or so. Luckily, I haven’t needed a jump. Does this sound like a battery, starter, or ??? Problem?
 
A hot engine turns over harder than a cold engine. Do you have the heavy battery cables, positive and negative? Those skinny little 12 volt cables from the auto parts store are not adequate. Check your battery and starter connections. Also, check your Positive ground strap where it attaches to the frame. Needs to be clean. If your frame is rusty, you can attach a positive ground cable directly to the flywheel housing on the engine. Makes a big difference.
 
If the engine has few miles since a rebuild, there is a possibilty that you don't have enough piston to cylinder wall clearence for pistons 3 and 4. I had an engine with this problem and it took some time for wear to increase the clearence. Just leave it idle and the cooling water will continue to circulate.
 
I had the same problem when I used to own my 46 Ford (Flathead V8 & 6 volt positive ground). Changed the battery cables to 00 gauge and noticed immediate improvement. Later-on the starter started to slow down a bit but after a starter rebuild, everything was good again. So, if your cables are already proper size, I would suspect the starter may be getting tired and needs a rebuild or replacement. If the cables are small, try replacing with larger cables first. Hopefully you will resolve the problem soon.
 
Bad battery or cables are not the right size like stated. Similar things happen when you use an extension cord of incorrect guage with a big piece of equipment like a lathe or drill press - the full amount of power does not get to the motor thus it is turning at a slower rpm.
 
When the starter bushings wear , it can cause the armature to drag on the field shoes . The bushing on the drive end of the starter will be the first to wear out and cause starter drag .
 
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I totally agree with Paul, re: proper grounding. Clean the frame where the ground strap is attached to make sure nothing, including paint is inhibiting proper ground. Of course, proper 6 volt cables are a must.
Good luck.
Rog
 
As suggested, running an additional ground cable from the from a ****** or bell housing bolt is good insurance of maintaining a good ground. Chap
 
According to the original post, this has happened twice. Out of how many? Twice out of 20 hot starts, 2 out of two? Anyway, I think the two most logical answers are poor ground or starter getting tired. Running a ground strap should be SOP anyway, so I'd get that done then keep an eye on it. It may also be a good idea to use the crank a few times to get a feel for how the engine turns over hot, then when the problem happens again try turning over by crank and see if the engine feels tighter or not.
 
Okay. I’ll try the ground strap first. The current ground is heavy wire, but I doubt that it’s 00 or 1.
To answer the questions about rebuild and number of starts. I’ve put about 50 miles on her since having the head refaced and putting in new, adjustable valves. I have only had her stopped to top off the fuel tank twice and that’s when she was slow to turn over.
 
The compression went from high 40’s and low 50’s to 60psi in all cylinders. I can see some difference, but people with high compression heads don’t seem to have problems. When I say “slow turnover”, I should say “barely turns over”.
 
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