Several days ago I was going through all my Chrysler parts & stood there looking at my "stash" of Chrysler starters- I have 2 short frame, & 1 long. I was curious as to what was the differences were among the three. I hadn't really thought about it much before- to me the old Chrysler starters were interchangeable thus "they were all the same" - (NOT!!). This led to web searches & several very good posts by SlantSixDan- including one from 20 years ago. So it looks like I have: an older 1.3HP, a "late" 1.3/1.4HP, a 1.8HP, (& a ND mini starter as well).

Now I had these starters & wondered how they would compare directly to each other. I had the parts, I had a car, & I had some of my lunch hour remaining; so-oooo let's swap & test. The Chrysler starters are crusty rebuilt-who-knows-how-many-times crapshoots. The ND was purchased new 15+ years ago. The engine is a rebuilt 225 in my Valiant- has about 180psi compression.The battery is old & a bit weak- but adequate, charge was topped up during testing. Since the condition of the starters are highly "variable", I can't perform absolute tests of the different types & how they would perform. Nor did I see how the starters performed under severe cold or hot-soak conditions. However, if you can't do as Dan suggests & get a GOOD local shop to build your starter, this is a "real-world" comparison of what you might find in your car - or in the chain store's box. (honestly, I had some time to kill & like playing with my scope- so here it is).

What you are seeing on the following captures is the starter draw in amps (blue trace) & battery voltage (red trace) . As each cylinder comes up on its compression stroke, amps peak then drop until the next cylinder starts to compress. What I really like about using a scope is that it permits me to SEE voltage changes over time. I use an inductive (hall-effect) amp clamp on the battery (+) cable to convert amps to millivolt output for the scope. A voltmeter would only show you the average amps. I can look at this amperage waveform & determine that all the cylinders have fairly EVEN compression- within about 5 psi. If a cylinder had significantly higher or lower compression you'd see higher or lower amp peaks. This test is called a "relative compression" test & I use it often when I diagnose customers' car at work. Someone with an experienced ear can hear the change in cranking cadence if a hole has low comp, but even after 25 years of fixing cars I can't "hear" a difference of 30 psi- but I can see it. If I put a compression gauge in a cylinder I get a "comparative compression" test- the gauge tells the psi of the "known" cylinder & the waveform lets compare it to the others. AND you can "sync" that waveform from the known cylinder to ID any other cylinder that may need additional testing. With this I can "do" a compression test on most cars in under 10 min. How cool is that? Scopes aren't for everyone, but once you figure out how to use one & what it can do, it's the bomb-diggity.



First up is the 1.3HP Chrysler short frame starter, which began life as a # 2875-560. This is the "classic" Chrysler sound while cranking- that "dut-dut-dut-dut" any mopar-nut will recognize- but a little slow. It still is a 3 field coil with shunt. It spins my slant at 130-135rpm while pulling about 145 amps. The amperage waveform has some strange "ripples" (changes in current draw) that could be dirty spots on the commutator or something. Doing the gear-reduction math (122 tooth flywheel divided by 10 tooth pinion times 3.75 OSGR ratio= 45.75 rpm per eng rev -same as listed in my 63 FSM) puts the motor speed at 6000 or so (which is very close to the frequency of the ripple).



Next is another short frame unit- a "franken-reman". It has a #2095-150 frame with 4 small field coils & an external retainer-screw solenoid housing. It weighs 15lbs- same as the older 1.3HP & performs almost the same. Draw is up by 10 amps to 155, but rpms are pretty much unchanged at 130. The amp waveform is much "cleaner" than the previous one.



Third is the long frame 1.8HP - # 4111-860. At 17-1/2 lbs it's a monster of a starter. It does crank the engine faster- rpm's are up to 160 rpm, but pulls 170 amps to do so. With a starter ratio of 2.0:1, the motor itself spins at 3900- less rpm but uses more amps to make more torque. It's also interesting (in a geeky kind of way) how the min to max amp range is much higher,60A instead of 40A. Like others have said, it sounds like a normal chrysler but "turned up to 11".



Last is the NipponDenso unit, part # 53005984. Compared to the Chrysler starters, the ND is a featherweight- weighing only 8-1/4 lbs. On the car it's the starting champ- my slant cranks at 175 rpm at only 145-150 amps. This also has high amperage range- 65A from min to max peaks. I assume that as cranking rpm goes up, the amps range from one compression stroke to the next will increase as well. I read that is uses a 4.0:1 gear ratio, so the motor is doing 8500 while cranking. So how does it go faster but use the same or less amps? - Permanent magnets, that's how. The Chrysler units need power for the field windings to produce the electromagnetic field that the armature works against. The ND's magnet design means that all the power is being used for the armature. It has a cyclical higher pitched sound when operating- like a variable speed electric drill. It's a "normal" to me because I've worked on hundreds of cars with ND starters over the years. On modern cars the engines are spun hard, 200-230 rpm is common; & start fast, typically in under 2 full engine revolutions- say about a half second.

On a side note, I checked a couple things that could be affected by the cranking speed. When I had the ND unit installed (175 rpm)- AC voltage from the distributor pickup was about 400-500mV & engine compression was 180-185 psi. With the short frame chrysler (130 rpm) the pickup volts was 300-400mV & compression was about 5 psi less.

update
So-ooooo, after writing this, I thought that some of the starters should have done better- even for old remans. I cracked open the Chrysler units & gave the 1.3 shunt & 1.8HP units- "no buck tune-ups". (the 4-field "1.4hp" was shiny on the outside, fugly inside, & not worth the time to fix). Apparently mass rebuilders no longer bother to undercut commutators or do other basic things- helping to insure quicker failure. I burnished the commutators with a file & emery cloth, gave them a light undercut, then cleaned up the solenoid contacts & some connections (esp. the field frame to case joints), & lubed the bushings/ gears. Then I swapped in a slightly stronger battery for kicks.

This really woke up the 1.3HP shunt starter- how's 150rpm sound? - actually it sounds just about right for a slant.And amps DROPPED to 135A at 10.9V. Ahh, less friction is a good thing.
The 1.8HP starter took off like a rocket- over 195 rpm at 150A & 10.7V. The amp min/max range was also down from 60 to 40A. Hard to describe the sound when it's that much faster than what you're used to.
I didn't do anything to the ND, & both rpm / amps for that were unchanged, even with higher volts available from the replacement battery.

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63 Valiant Wagon
225 - 4 bbl

nice work!

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Yeah....Im the one who destroyed this rare, vintage automobile.....

This post and this page: two great tastes that taste great together!

(I haven't yet seen/heard one of these cranking a slant-6)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

But I like it. Nice work guys!

WEIRD - and proud of it!! (normal is over-rated, as well as boring)

I'm getting material together for a charging system write-up & a HEI edition as well.

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63 Valiant Wagon
225 - 4 bbl

Exactly! I look forward to your write-up. This sort of in-depth and quantified and accurately measured information is the reason why I like slantsix.org MUCH more than any other car related message board I have found.

Wow, what a great bit of work! I wish my lunch hours were that productive LOL. Now I know what I need to be doing with my old low bandwidth Tek 422.... and a reason to get a working battery pack for it. Many thanks for sharing this!