Are all flathead starter motors basically the same or do some have higher starting torque.
p.s. I think I am missing a spring between the gear and base of starter, right?

 

They are basically all the same, as far as torque goes. They all interchange as well, even 6 cyls. Not positive about auto trans ones. Both in the pic look complete.... no spring, the flywheel kicks the gear out on start up.

If yours is weak, or slow, it probably needs rebuilt. They are very fixable....the "new" starters are offshore junk IMO......

 

Looking for advice here...I am restoring a 1949 F3 with flathead V8. Engine is newly rebuilt and I installed a new 6v starter with updated Bendix from MAC's. Also the 6v battery is a new Interstate with 610 CCA. The engine turns over without the plugs (but somewhat slowly) and not at all with the plugs installed. Battery cables get hot at the starter relay terminals, implying that a lot of current is being sent to the starter, but it just won't do the job. Grounding has been checked. Postive ground, of course.

Someone told me to try a 12v battery, but use it with negative ground. Is that right?

Any ideas?

CarlH
1949 F3
1997 F150

 

Hello. You'd probably be better served to ask your question as a brand new thread so that more people will take notice and try to help. But, in the meantime, the first question I would like to ask is what size battery cables you're using, especially considering you say they're getting hot? A 6 volt system requires particularly large cables (like a 1/0 or 2/0 at least). The typical battery cables (intended for 12 volt systems) hanging on the shelf at the local auto parts stores usually aren't enough.

 

Make sure the ground cable is connected directly, and firmly, to the engine, not the frame. One of the bellhousing bolts would work fine.

If you replaced the solenoid with an offshore copy, it could be part of the problem. Copper is expensive.

PS -- if you try a 12v battery, you use it Pos. ground, and you probably want to disconnect everything except the starter and a temporary feed to ignition. The 6v battery should be out of the truck. Or you can leave the 6v in, turn on the key, and use the 12v directly to the starter (only) using jumper cables to the solenoid post that goes to the starter.

 

Thank you for the replies....I am on another thread on restoring a 1949 F3 and have gotten similar advice there, but figured a Starter Motor thread might be more to the point. I am aware of special gear reduction starter motors available for other specialty cars (e.g., British sports cars) and wonder if there is such a thing for our old 6v flatheads.

My cables are sized for 6v, so that is not the problem. I will try the 12v battery next.

CarlH
1949 F3
1997 F150

 

Back to my starter problem: Bolted tight, the starter just groans and the solonoid clicks. Loosened a bit, the starter turns over the engine slowly. Sometimes the engine catches and runs. Timing checks out OK, so it is not that.

New ring gear....maybe oversized? Is there a difference between a car engine and a truck engine?

CarlH

 

I've recently installed a starter from Mac's with the new style, enclosed bendix.
First, it was quite difficult to get the new bendix in past the flywheel, 'cause the new bendix is a slightly larger diameter than the old.
Finally in and wired, just a click from the solenoid. Been checking voltages and cleaning connections (not finished yet), but I'm betting the new starter just doesn't work.
The old starter just got slower over the years and finally couldn't do it.
Upon disassembly, the mica is up at the top of the commutator, all that stuff that needs to be rebuilt. Should have done that, rather than go with the "new" starter.
I'm just worried that I'm not going to be able to get the new starter out around the flywheel.

Jonas

 

Jonas,
You are having the same experience as I have been having with that "new" starter motor. One of the previous MAC's catalogs had a note that the spring cover on the new style Bendix needs to be shaved down 0.1" to pass the ring gear. The current catalog has no such warning so I assumed it was not necessary.
Wrong.
I forced it in all right, but I had to loosen the lower cover to the bell housing to slip it past the ring gear when I removed it. Then I shaved it by running it off the 6v battery with a flat file on the spring cover. Now it slips in and out OK, and I have done a lot of that with experimenting with various shims and alignments. Nothing has worked so far.
This motor appears to lack the power to turn the flywheel. I think I will go back and get my original starter rebuilt with the old style Bendix.

CarlH
1949 F3
1997 F150

 

Pop off the "cup" on the backside of the bellhousing with the starter installed. (May not be easy) turn the bendix in by hand and see if the teeth mesh properly, and at the correct angle. There are unfortunately a dozen or so different "starter plates" with different angles. Here is an exhaustive article on the situation: http://www.flatheadv8.org/bellhousing.pdf

 

One other thing you guys should do to verify that you're getting enough power to the starter is to measure the voltage drop at various points. Ross suggested that the solenoid could be junk & that is easy to measure.

Use a multi meter in the DC volts mode. Keep in mind that the multi meter measures the difference in potential between two points....so, if you put one lead on the plus side of the battery and one on the minus, the difference in potential should be around 6 volts (really a little more...a battery cell has between 2.1 and 2.2 volts when fully charged, so your 6v battery is really a 6.6v battery).

Along the same lines, if you put the black lead of the multi meter on the battery side of the solenoid, and the red lead on the starter side (for positive ground systems), it will read the difference in potential between the two points....have somebody crank the starter and read the meter while cranking....any voltage reading that you see is the difference between the two points, and therefore the drop in voltage. If you see more than a volt or so of drop at the solenoid, it is indeed junk. You can do the same test from the battery lead all the way to the starter and see the drop in your entire for the combined battery cables and solenoid. In 12v cars, the acceptable drop is around 2 volts....so I'd guess that in the 6v system, with fat cables and a good solenoid, the drop shouldn't be more than a volt or so.

Also, it wouldn't hurt to see how much the battery voltage drops under a cranking load....what kind of test did they do to your battery at the auto store?

Dan

 

Ross -

How do you pop the cup off the back of the bellhousing? like a wheel bearing cap? Bop it with a rubber hammer, or pry it off? I downloaded that article, have to study it later, thanks.

Dan -

Thanks for the troubleshooting tips, that's what I've been doing. I get 6.14v at the starter end of the cable when it is disconnected, so I think I'm good - or does it have to be under load? 'Course during all this I had to disassemble my remote starter switch and resolder some parts to get it to work. Grumble.

Jonas

 

Here's a picture, it is similar to a wheel bearing cap but goes in deeper, so knocking it back and forth needs to be combined with pulling outwards

 

Unfortunately I used J&B Weld on the can cover on my bellhousing. Some previous owner had removed and lost the original and I got another one courtesy of a friend on another FTE thread. It was a loose fit, so I glued it on. Wish I hadn't because it would be nice to see how the pinon meshes with the ring gear.

Good luck in getting yous off. I understand the original was pressed in pretty tight.

CarlH

 

Jonas,

You should test the battery with a load. The auto store should test with a tool that loads it....so the real test is to fully charge the battery, then put a load on for several seconds, & watch the meter.

In the truck, you're really just looking to see if it drops off to a really low voltage when you crank the starter. It will drop because the starter puts a really big load on the system....so as long as it's charged, see what it drops to during the cranking. If it drops down near zero, the battery may be an issue. If you've been doing a lot of engine cranking without running it, you may need to charge up the battery for a while.

Dan