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65 amp alternator or 100 amp alternator
Posted by: macutak ()
Date: March 15, 2017 07:39PM

Does anyone have advice on which you would choose for a
63 Rampside FC truck that has a 102 car engine in it but no new electrical toys. It has electronic ignition and a digital radio but that is about it. Any worries a 100 amp would overpower things?

I aint in it for the money. Just can't figure out what I am in it for.


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Re: 65 amp alternator or 100 amp alternator
Posted by: MattNall ()
Date: March 15, 2017 07:40PM

Stay with the 37 amp... it's all you need....IMO!





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Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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Re: 65 amp alternator or 100 amp alternator
Posted by: oldqmguy ()
Date: March 15, 2017 08:10PM

Just to be clear, the Ampere rating of an Alternator (or Generator) is an indication of "how much" current it can supply at its rated output voltage.

Larger rated alternators are only needed if additional electrical equipment is installed that need more current than the stock unit can supply.

I do recommend using an internally regulated alternator to simplify the system.

Dale cool smiley

Dale E. Smiley CPBE
Life Member The Society of Broadcast Engineers
RETIRED Broadcast Engineer
CERTIFIED CORVAIR NUT
CORSA/Circle City Corvairs/Corvair Performance Group
Avon, Indiana
WB9SFF
1967 4-Door Monza PG!

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Re: 65 amp alternator or 100 amp alternator
Posted by: Seth Emerson ()
Date: March 15, 2017 08:34PM

And it is probably cheaper, if you are doing the conversion from Generator to Alternator, to buy a rebuilt internal regulator unit, swap on the Corvair front housing and fan, and wire appropriately. You never know if the external regulator is okay or not. The 63 Amp Chevy Van unit is in almost every parts store in America.

Seth Emerson

Check my new Performance Corvair Web site [www.perfvair.com]

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Re: 65 amp alternator or 100 amp alternator
Posted by: Timothy Shortle ()
Date: March 16, 2017 07:53AM

I like to use the high volume heater fan motor. For that I use the 63 amp internal regulated alternator though I know most of the charging ability is not used or needed. As I said on another post I use this set up also to simplify the install as Dale states.

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Re: 65 amp alternator or 100 amp alternator
Posted by: 66vairman ()
Date: March 16, 2017 09:38AM

I assume you are talking the "internally" regulated 100 Amp conversion. First an alternator only supplies what is demanded of it and I doubt you need 100Amps. Second your basic FC wiring will only handle about 60Amps!! The Corvair unique (revese rotation) Delco alternator fan is rated at an 80Amp cooling MAXIMUM. Finally some 100 Amp aftermarket units don't even put out as much amperage at low RPM as the stock Delco units!!!

The Corvair external regulator alternator was a Delco 10DN model and as Matt said the 37 Amp unit is adequate for non-A/C vehicles.

The internally regulated Delco alternator was the 10SI and went up to 63Amp. Most folks put the unique Corvair fan/pulley and front 10DN frame on a 10SI 63 Amp and revise the wiring. It's a good, and relatively inexpensive, upgrade. More importantly 63Amp is about he maximum your stock wiring can handle.

Finally - alternators are rated at MAXIMUM Amperage and at lower RPM they won't produce maximum Amperage. You can look at the alternator charts to see how much amperage a unit develops at typical alternator RPM (calculate pulley ratio to find alternator RPM vs. engine RPM). As mentioned before some of the aftermarket units don't produce as much amperage at "usable" RPM as stock Delco units. But folks just see the maximum amperage rating and spend the money.

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Re: 65 amp alternator or 100 amp alternator
Posted by: coleslaw31 ()
Date: March 16, 2017 10:26AM

Hey I am looking into a higher output alternator for my convertible. it will have a/c has a fm radio also so figured a little boost in power wouldn't hurt. Also planning to go internal regulator so assume it would be for a 70's Camaro or something?

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: 65 amp alternator or 100 amp alternator
Posted by: cnicol ()
Date: March 16, 2017 10:44AM

FWIW, the factory deemed 47 amps the right number for a Corvair with AC. The draw of an AM/FM radio is, as a practical matter, identical to an AM radio and negligable.

The system wiring is rated for about 55 amps maximum.

A properly tensioned (i.e. slightly loose) 3/8" belt doesn't have enough "traction" to actually turn a 100A alternator at full load.

... so based on the above, what do you think is an appropriate upgrade?

Also FWIW, my old diesel Suburban had an 80 Amp alternator to recharge the dual batteries in a reasonable time after a cold, glow-plug start. It had dual 7/16" belts on the alternator pulley and even with dual belts at high tension, the alternator pulley would squeal after a cold start (i.e. 80 amp/full output).

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later

+17 Tons of parts

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Re: 65 amp alternator or 100 amp alternator
Posted by: gnvair ()
Date: March 16, 2017 10:50AM

People get greedy with the amperage. The reality is that the higher amperage alternators came about because of high draw accessories such as blower motors, power seats, rear defrosters, electric fans, abs or suspension pumps, etc. When under a load they do require more effort to turn.

Lee J

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Re: 65 amp alternator or 100 amp alternator
Posted by: moomba32 ()
Date: March 16, 2017 10:58AM

For the most part any of the alternators will be enough, even if you add stuff like air conditioning or high power stereo how often will you be running everything at night with lights on? More power may charge a low battery faster but as Craig pointed out you probably can't spin it. I would go with simplest and lowest cost.

Don Marlowe
66 Monza 2Dr 140/pg
64 Spyder convertible now, 110/pg
Eutawville SC

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Re: 65 amp alternator or 100 amp alternator
Posted by: coleslaw31 ()
Date: March 16, 2017 11:07AM

So a standard alternator is okay, I do plan to add electric fans to the condenser. I see there is a 63 amp alt I could go with? Just getting ideas, planning to run a stock alternator for now.

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: 65 amp alternator or 100 amp alternator
Posted by: jjohnsonjo ()
Date: March 16, 2017 12:30PM

Many of the FLAPS rebuilds now use the 47 amp armatures. I load test my and it will pull it.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: 65 amp alternator or 100 amp alternator
Posted by: Lane66m ()
Date: March 16, 2017 12:35PM

Go with an internally regulated alternator. I posted on your wiring harness thread what a local rebuilder did to mine. Just make sure you have the bare minimum for your vehicle, if you get yours rebuilt.

Al Lane
Ellabell GA

1966 Monza Coupe, 110 hp, 4 Spd
1966 Corsa Turbo Coupe, 180 hp 4 Spd
1964 Greenbrier Deluxe, 6 dr, 80 hp car engine, PG
2015 Chevrolet Malibu 2LT
2015 GMC Sierra SLT Crew Cab
1968 Camaro SS Coupe 350 CI 295+ HP PG
1947 Farmall A tractor 15 hp


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Re: 65 amp alternator or 100 amp alternator
Posted by: curt ()
Date: March 16, 2017 01:57PM

Alternators pull energy and energy loss is loss of HP to the wheels. Keep amps to what you expect will be needed.

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Re: 65 amp alternator or 100 amp alternator
Posted by: rnch ()
Date: March 17, 2017 06:22AM

MattNall Wrote:
-------------------------------------------------------
> Stay with the 37 amp... it's all you need....IMO!



I had a LM 110 with after market, add on A/C. (I still have the add on A/C kit!)

The 37 amp alternator did fine for this car; no dimming headlights, slow turn signals or battery charging problems.

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Re: 65 amp alternator or 100 amp alternator
Posted by: Gregory_Miller ()
Date: March 17, 2017 02:51PM

I also did the internally-regulated alternator conversion, stuck with the 37 amp sized unit.


I also used a failed external regulator, gutted it so it's simply a jumper for the 4 wires, and looks stock.

Greg Miller
Eugene, Oregon

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Re: 65 amp alternator or 100 amp alternator
Posted by: jjohnsonjo ()
Date: March 17, 2017 03:18PM

Not 100% true, but for the most part, the higher the amperage rating, the lower the efficiency rating. Mostly due to higher IR losses.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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