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Tucker Snow Cat charging question

T

Tacoman

Member
1984 Tucker 1342 with a 318cu Chrysler Industrial Engine.

I put a Odessy AGM battery in the vehicle. The charger will not sustain much more than 12v at idle. It will come up to 14v at about 1500rpm engine speed. I have had AGM batteries that would not fully charge in a daily driver (Toyota FJCruiser) unless the charging system was modified with a diode that brought the charge voltage up to ~14.5volts at idle. I have changed the voltage regulator which makes the voltage somewhat better at idle speed but still low. Questions: Is this just an under-performing alternator that needs to be replaced. Every thing checks out (grounding, voltage drop, ripple, etc). It is listed on the build placard as a 60amp alternator and they are a number available from RockAuto at a reasonable price. Does anyone know specifically which alternator it would be? It has a rebuild number stamper on it which does not cross over to anything that RockAuto sells. I strongly suspect the correct altuernator is from one of the Dodge trucks. Is there a similar mod that can be done an the Chrysler system, like adding a diode, to bring the charging voltage up? I was also thinking of putting a smaller pully on the alternator to spin it faster, if I can find one.

Any Questions, ideas, answers or observations?
Thanks
John
 
My experience is alternators dont charge much at idle.

You can make them. (Pulley modified electronics) but then at 2600 rpm you are working the day lights out of the regulator for the exact opposite reason.

The demand on the alternator is very low in a tucker. Couple of lights and a blower motor. Recharging a good battery is a short affair.
 
The 60-amp Chrysler square-back alternators are known for being weak at idle. You can usually swap it for a Denso-style "mini" alternator or a high-output Chrysler version from a late-80s Dodge truck. A smaller pulley might help, but the older internal design just doesn't produce much current at low RPMs.
 
Handy
Could you suggest a high output replacement alternater. There are a number on RockAuto for dodge trucks rated for 90/100amp output. Will I have to change any other parts (voltage regulator or basic wiring)? The current setup has 2 belts and the normal square back mounting.
John

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Tacoman said:
Handy
Could you suggest a high output replacement alternater. There are a number on RockAuto for dodge trucks rated for 90/100amp output. Will I have to change any other parts (voltage regulator or basic wiring)? The current setup has 2 belts and the normal square back mounting.
John

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Click to expand...
Look for a Bosch or Denso style alternator from a 1988-1990 Dodge Ram with the 5.9L engine. These are often rated for 90 or 120 amps and have much better output at idle than the old square-backs.
 
Thanks for the reply. The approach looks promising. I am hoping for a simple part-for-part swap. Couple of questions:

Will the same voltage regulator work? The current regulator is a Chrysler part 4111990, that part number is listed as one of the cross referenced replacements for the higher output alternators in the Rockauto catalog. Based on that, I suspect it will work with the original regulator.

Does it mount in the same way as the square back? Rockauto catalog lists the same alternator mounting brackets for each type of alternator but it is hard tell if these are different than the ones originally on the SnoCat with out measuring each. It kinda looks like it might be the same, I am a little concerned about the setback back from the belts.

Two belt verse the 7groove belt? The 7groove is wider and is typical of the higher output (90-100amp) alternators. Can the 7groove and the two belt pulleys be interchanged on the alternator shaft? I don't want to try to find a 7groove pulley for the engine side of the setup and a belt to match.

This may be getting too deep down into the details. We just got some fresh snow, so the job may have to wait until the spring. It will have to stay on the charger at night for the time being. In the meantime I will gather parts.

Thanks again for the help and any new help you can provide.
John
 
I found the dimensions of the Denso alternators on the "Tuff Stuff" website. Unfortunately they are too large to fit the available space. It would be a major project to make it fit. The pulleys and mounting brackets would all have to change. The existing unit is at least 1-1/2 shorter and it barely fits as it is. I am going to order a replacement from RockAuto (total of about $50, delivered) and see if a newer reconditioned unit will charge at lower RPM. I might even try to find a smaller diameter pulley to spin it a little faster if that doesn't help. There are also adjustable voltage regulators that may help get the voltage up. In the meantime I will enjoy the fresh snow.
 
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