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Bringing this up again:

I had a nice experience a few weeks ago when I discovered my 12V starter just spinning in place. I pulled it to find out that the starter's bell housing had cracked completely off. I forked over the cash for another one and listened to cranking followed by a loud BANG. I looked and found the teeth of the starter and flywheel jammed together.

I'm pretty ticked about this because I made sure the diameter and number of teeth of the new starter matched the old, but this doesn't mean anything if the PO didn't have the right starter on the truck in the first place.

I have a new theory that the teeth on either may be too worn down to engage at the right pitch. I checked the flywheel and it doesn't look to bad, but the "new" starter from Jim Carter looks pretty worn compared to the other 2 starters I've now seen. I'll double check exactly what flywheel I have down there, but need this answered:


How many teeth on starters and flywheels between the original 47-54 6V's and the later 12V's?

My starter has 9 teeth with a diameter of 1.00" (pitch of 0.349"). What flywheel am I looking for?

(by the way I have all Chevy under the hood, not GMC)

I can tell you this...if you don't know what you are looking at, a 6 volt starter and a 12 volt starter look the same as far as the teeth go. I have been fooled several times and have had to guess because it is hard to tell the difference. Someone who works on starters all the time can tell immediately by looking. On the flywheels, you have 139 teeth (6 volt) and 168 teeth (12 volt). Your starter and flywheel shoud be 139 teeth and 6 volt, if you are stock.
You might already have this information, but thought it might be of some use.
Good luck!
Joe

So both types of starters have 9 teeth?

I can be corrected if I'm wrong, of course, but I think that is the case. I know for a fact that it is hard to look at both, side by side, and see the difference. I've done that. Let's see if anyone else agrees or disagrees.
Joe

I believe that all '50s and '60s Chevy starters had the same 9 pinion teeth. From the start of 12v in '55 through '62, ALL Chevy flywheels were 168T. I don't know how far back 139T/6V went. In 1963, Chevrolet started using 153T for BBCs to spin the engines a bit faster, although not all BBCs got the 153T flywheel. The difference is in the bellhousing casting, until you get to the "bolt to the block" starters.

Best wishes,

Les

If you had a 6v and 12v starter laying side by side, the 9 tooth gear on the 6v would be a slightly larger diameter. The other way of distinguishing between the two is the diameter of the armature shaft at the exposed bushing end.....the 12 v starter will be .470" while the 6 v starter has a shaft diameter of closer to 5/8".

You just need to make sure you match the 12v starter with the 168 tooth flywheel and the 6v with the 139 tooth wheel. Both flywheels will fit on any year of 235 and it sounds to me like you've got the smaller 12v starter bendix drive gear jamming on a 139 tooth 6v flywheel.

Should this be the case, you need to run a 6v starter on 12 volts which is a common practice. If you set it up with a foot-stomp starter, you don't need to make any modifications to the 6v starter. However, if you run a solenoid controlled 6v starter, you'll need to switch the solenoid to a 12v. I found that our local NAPA carries starters and solenoids for Chevy 6's.

Dave

Thanks much, Dave. I'll measure the diameter.

GMC's had a 12V system with the foot stompers. They had to make 12V starters for those early GMC's didn't they? Or did the early GMC engines not have 139 teeth?

There were plenty of 12V starters with foot stompers for 6 cylinder Chevy task force trucks. 12 and 6V GMC flywheels share the same tooth counts as the Chevy counterparts but not bolt patterns at the crank.

Keep the original flywheel. Take the original 6v starter to a rebuilder & have them convert it to 12v. I have some experience with big blocks & all have used 168 teeth. The '58 thru early '65 big blocks were "W" motors so I can't really speak about those flywheels. 153 tooth flywheels were used on the lower hp motors. seems like a wide spread for a stock starter to go from a working 139 tooth to 168 tooth flywheel (not to mention the diameter).