I was rereading this thread and thought I would add this (I found it helpful and figured others might too): http://www.madelectrical.com/electricaltech/delcoremy.shtml
There's a lot of great information in this thread, thanks for that. I have a '73 that came with a 10SI. In the distant past I purchased a pretty chrome case 10SI. I've rebuilt the alternator and everything is working fine. I even rebuilt a stock 10SI as a spare. I think they are both 63 amp versions. My problem is similar to one mentioned that output at idle is low. If I run the headlights or the heater fan it can barely keep up if I run both voltage drops down to 12. If I add the windsheild wipers it gets worse. My commute takes 45 minutes to go 8 miles. Yes, 8 miles! A blistering average of 10 miles an hour. If it's hot and rainy running the A/C and the wipers drains the battery instead of replenishing it. Slipping the car into neutral or bringing the rpm's up a smidge bring the voltage right up (I have a volt gauge). I don't have electric fans or a massive stereo, I don't think I need 140 amps and would rather not rewire the car for amperage I don't need. I have a few questions for the experts. Will a CS alternator provide more voltage at idle than a 10SI? Is there a way to get the 10SI to put out more at idle? Will the stock wiring handle 94 amps? If I upgrade my 10SI to 94 amps will it's idle output increase? Thanks, John
Will a CS alternator provide more voltage at idle than a 10SI?Yes Is there a way to get the 10SI to put out more at idle?Smaller diameter pulley Will the stock wiring handle 94 amps?Borderline If I upgrade my 10SI to 94 amps will it's idle output increase?No,it might even decrease.
What you are talking about running are factory accessories - the wiring harness as built is designed to be able to handle all of those loads simultaneously - putting in a 94a alt (or 140a or 1000a) is not going to change the load you place on the system and "fry" anything. what you need is an alt. that can deliver a constant voltage > 12.8v under load at an RPM of 700-850 and the SI is not capable of doing that. Jamie's suggestion to go with a smaller pully on the alt. has the same affect as increasing engine RPM - but is only beneficial at low RPMs. If you wing the motor to 5,500 - 6K or higher, you could have other problems.
I am looking at an alternator for an 86 Riv. It still has 120 amps but has a smaller case than the LT1 piece which is important to me with since I have a belt drive oil pump tucked under the alt. The LT1 alternator like one I am looking at have a 4 pin pigtail. If it were adapted to a 455 in a custom body wired from scratch, anyone know which pin(s) need 12v sent to it to excite it? I am sure there are people on here who build great pieces but I would like to go get it today and like Silly said I would like to be able to go into a parts store with a lifetime warranty anywhere in the country when it ever goes out. Thanks!
Ok so I scrapped the idea of the alt from a Riv. I thought about the cs144 but it's bigger dimensions will cause me greif with my lower rad hose and Moroso oil pump. So I got a 105 amp cs130 and I got a conversion harness for cs to si with a resistor in it to simulate an idiot light so it will operate properly. OK so my questions: 1) the bigger "s" terminal wire is the sensing wire. Would it be better to have it see voltage back at the batt or just loop it back to the charging post. I have read in searching it makes a difference but seems pointless to me since healthy wire diameters are used so there shouldn't be much voltage drop. Thoughts? 2) The smaller "L" wire... I have removed all of the stock wiring so I can't just hook it into a factory wire. I know this goes to a factory light but I think this also energizes the alt so do I run it to switched ignition 12v? I am using a gauge and no idiot lights. Thanks!!!
