Another pulled from my old Goodysgotacuda.com site, hope it's helpful to someone.
Denso Style Alternator Swap on LA Style Mopar EnginesThis particular Denso alternator was pulled off of a 1990 LA 360, Dodge Ramcharger for $25 including core charge from the local junkyard. This alternator is rated at 90amps. Most stock replacements are rated around 50-60amps. This alternator uses the factory style voltage regulator (externaly regulated) and bolted right up on my factory brackets. My motor is Non A/C so the brackets may be different on your particular motor. If you are already getting the alternator from the junkyard, likely there is a non a/c small block you can rob the brackets from and be set. Vendors such as Mancini Racing or Magnum HP sell bracket kits as well. These particular alternators will put the output stud very close to the block. I chose to do some minor trimming of it to keep it off the block, it also has a plastic shroud around it. There is now about 1/2" of clearance between the block, and my alternator's output stud. Which is plenty.
Lug Trimming:The alternator I purchased had the stud, a nut, the output lug, a nut, and the shroud. I chose to do away with the first nut and only use one due to clearance. My setup goes, the stud, a nut, the output lug (6 gauge), 3 small washers, and the shroud. Some minor trimming of the inside of the shroud was needed to clear for the lug that would accept 6 gauge wire. 3 washers go on after the shroud on the lug, then the lug, and the old bottom nut that comes with the alternator. With that done, everything tight, mark the stud a thread or two above the nut. This is where you will trum the output lug. I chose to thread the nut on the stud and use a cutting wheel to cut the lug down. After that, you can put it back together and take note how much you can take off the shroud. I ended up losing about 1/4" off the stud and the shroud which gave me the extra clearance that I needed.
Belt/Pulley Alignment:The alternator comes with a dual belt pulley, you can use either...however since you need to space it away from the block, you will likely use the inside most pulley groove for your belt. Making new spacers is very straight forward, you can grab some spacer material off a few other cars at the junkyard if you are there to cut-to-size for your application, and some small washers can be used to take up any needed clearances. Since there is no threaded insert in the alternators case like the stock style alernators have, you will have to use just a nut, washers, and a bolt to hold/tighten the alternator to the lower bracket.
A shorter belt was required, I am running a Duralast #15455 belt, it will cross reference to a few different brands if necessary. It is 45 1/2" long.
Wiring Upgrade:Since the Denso does put out a good portion more power out than the stocker, it is recommended to upgrade the wiring as well. One very popular step is to bypass the factory AMP gauge via how M.A.D Electrical explains. Reading this article will also explain why the AMP gauge setup is such a poor design and should be bypassed for system stabaility and safety.
http://www.madelectrical.com/electricaltech/amp-gauges.shtmlAfter that is done, I decided to go with 6 gauge wire, which is usually rated for up to 100amps. If you happen to pick up a 120amp alternator, 4 gauge would be recommended. I just seem to be one for overkill, but you definately won't have to worry about it not being able to support it. The 4gauge will require a good amount of shaving on the shroud to get the lug to fit in there, it can be done, and you defiantely want that shroud over the stud. As far as fusing the output wire, 120amp alternator I would suggest a 100-110amp fuse/breaker. And for the 90amp like i have a 80amp fuse or breaker. You can get such size fuses from most car stereo shops, however they are not cheap. The alternative I took was a 80amp Circuit Breaker made for marine use. Ran about $35 and is usually availible from your local marine store within a couple of days, or can be purchased online.
The 80amp breaker I am running is made by Blue Sea Systems and is part number - 7114 Thermal Circuit Breaker 80amp
The 100 amp model is Blue Sea Systems #7102 - Thermal Circuit Breaker - 100amp
Making Connections/Wiring:Since lugs in the 4 - 6 gauge range should be used, they are not the easiest things to crimp without the proper tools. The method I chose to use was solder. I placed heat shrink tubing over the wire, place the lug into a vice. And fed solder into the lug while heating it with a propane torch. Doing this will have the solder in a liquid state and inserting the wire into that will give it a very solid connection once the solder cools/hardens. Then put the heat shrink tubing over the lug and give it some heat.
Field wire connections can go to either stud on the back of the alternator. Thats your choice, usually the stock wires, have one longer/shorter so you can see which will work better when you mock up the alternator mounting. They will require ring terminals crimped on the factory wires to attach them to the alternator.
Driving with this alternator:Unfortunately the pulley size, like the factory is not ideal. When my electrical system is loaded down, I do run about 13v at idle still. Headlights, electric fan, electric fuel pump, aftermarket radio, aftermarket gauges, aftermarket headlights, etc, etc. I did upgrade the stock replacement voltage regulator with the Mopar Performance constant output voltage regulator. In doing this I gained a little more charge, at a little lower rpm versus stock. Ideally I would be able to find a smaller pulley from another alternator to install and gain more charge at idle, I have not gotten around to looking into that quite yet.
Hope it helps
-Mike
Topic: Goody's How To - Denso 90a Alternator on LA Small Block (Read 6927 times)
