benjy_26 Posted December 19, 2014 Share Posted December 19, 2014 Hey y'all. I came upon some free time today and decided to go to the local pick a part. While looking around, I noticed that the alternator used on the old LT1 equipped Buick Roadmasters looks an awful lot like the one on my 87 2.5 non-a/c truck. I looked up the two alternators at my local parts place and came up with some interesting specs. Both take a 6 rib belt, both are internally regulated, both have the same connector type, and both have the mounting legs in the same spots. There are two differences. One is that the MJ unit has the connector clocked to the 7 o'clock position and the Roadmaster alternator has its connector at the 4:30 position. The other is that the MJ unit puts out 73A while the Roadmaster unit puts out 140A (?!?). Do you guys think it would be a big deal to modify/lengthen the connector to work with the Roadmaster unit? Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 19, 2014 Share Posted December 19, 2014 Mine if for a '86 Caprice. 105 amp Link to comment Share on other sites More sharing options...
benjy_26 Posted December 19, 2014 Author Share Posted December 19, 2014 Cool deal. Is your truck A/C equiped? I ask because depending on whether or not it is, the connector is in a slightly different spot. Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 19, 2014 Share Posted December 19, 2014 Yes, it has AC. I reclocked the alt. Link to comment Share on other sites More sharing options...
benjy_26 Posted December 19, 2014 Author Share Posted December 19, 2014 Pardon my ignorance, but how did you do that? Link to comment Share on other sites More sharing options...
87Warrior Posted December 19, 2014 Share Posted December 19, 2014 Does anybody know if it would be possible to remove the serpentine belt pulley from a replacement alternator and replace it with the V-belt pulley? I am not familiar with their interchange and would like to upgrade my '86. Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 19, 2014 Share Posted December 19, 2014 Pardon my ignorance, but how did you do that? Remove the bolts, turn the back where you want it, reinstall the bolts. Link to comment Share on other sites More sharing options...
benjy_26 Posted December 19, 2014 Author Share Posted December 19, 2014 Pardon my ignorance, but how did you do that? Remove the bolts, turn the back where you want it, reinstall the bolts. Nice! I CAN have my cake and eat it too! Thank you for the info. :) Link to comment Share on other sites More sharing options...
benjy_26 Posted December 19, 2014 Author Share Posted December 19, 2014 Does anybody know if it would be possible to remove the serpentine belt pulley from a replacement alternator and replace it with the V-belt pulley? I am not familiar with their interchange and would like to upgrade my '86. I've never seen an '86 alt, but I've done that on my old Ramcharger and K5. An impact gun is handy for that. Link to comment Share on other sites More sharing options...
DaveJ33P Posted July 25, 2015 Share Posted July 25, 2015 I know that this is an old thread, but maybe someone will notice it and respond. I bought a '96 Buick Roadmaster 140 Amp alternator based on this thread and another I found here on the forums. It is WAY too big to fit into the stock mounting brackets. The distance between the mounting bolts is over an inch longer than my 61 Amp stock alternator on my '88 2.5L. How do you guys get it to work, What am I missing? Link to comment Share on other sites More sharing options...
DaveJ33P Posted July 28, 2015 Share Posted July 28, 2015 Here is some more information for anyone that cares to chime in. This first pictures shows the mounting brackets for the Delco CS121 61Amp alternator that is installed on our '88 MJ 2.5L no a/c pickup. You can see there is no adjustment that would allow something larger to be installed. These next two pictures are of the original alternator and the '96 Buick Roadmaster that fits Benjy_26's 87 2.5L no a/c truck. On-line research says the '96 Buick Roadmaster's alternator is a CS144, (144mm diameter frame) My calls to the local alternator rebuilder says both the '87 and '88 MJ should use the same alternator. That agrees with Autozone and Napa counter jockeys that tell me its a Delco CS121, (121mm diameter frame) There is also a CS130, (130mm diameter frame) that is supposedly as common as field mice in GM cars. The ear hole to ear hole spacing on my CS121 is 6.170" which agrees with info I found on-line. The ear hole to ear hole spacing on the CS144 is 7.200" Some websites say the CS130 is the same as the CS144, but many more say it's 6.600" Most pictures of the CS130 are with the ears not directly opposing each other but offset. Perhaps these offset ears match the dimension of the CS121? (of course then I'd need a longer serpentine belt) Does anybody have dimensional information? Link to comment Share on other sites More sharing options...
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