I have underdrive pulleys on my camaro and the msd coils. i want to add the msd ignition box dis-4 p/n 62152 and adapters plus a few other things and am scared that my current oem alternator wont do the job. will moving up to 140 amp alternator be a good move and give me back a decent idle voltage?

It won't matter what size of alternator you put on, you assume the risk/factor when you installed the underdrive pulleys.

However, you can install a larger storage battery to help alleviate some of the problem. Once you're up in rpm's, then alt will output, but rpms has to be up, around 1500-1700 before alt kicks in.

Current alt will do the job, but you'll need longer drive time to recharge the battery. Swapping in the 140 amp is not a bad thing to do, but battery will recharge at is own rate whether OE alt is there or not.

Welcome to the Club, Lee.

To add to Everett's comments, my L78 came from the factory with a large diameter machined deep pulley on the alternator. Yep, no charge at idle. I removed it last year and installed a smaller one of the same style. Much better. Not perfect, but much better.
Oh, the original pulley is in the 'memory parts' box.

Its the risk you take. The higher amp alternator will charge a little better because of the extra windings but its output will be low too.

There really is no need for a new alternator the msd won't drain your battery and how long do you expect to idle? On a V6 i see no problem at all unless you have a stereo system.

its tolerable when there is no load, but when i add lights, wipers, radio, ac...its a pain and sometimes goes dead and it has a new battery. the pulley kit came with a crank and alternator pulley...should i just put back the oem pulley and/or get an optima deep cycle battery?

An optima should clear the problem up they are expensive though. Its up to you man. Looks like you are spending alot of money to make power out of a v6.

You are putting to much load on the electrical system for idle and a low amp constant rating. When its idling turn things off don't run everything or u will have prblms

i know its just a v6 but its kind of a project....i just wanna see whats the most i can get out of it lol. it prob would be easier to just start over with a v8 but thats been done to death so i wanna try something different. there is a lot of bad hype about the 3.4l bc of its heads and drive train setup so i wanna see what it can really do fully modified

Dont forget to increase the wire size from the alternator to the battery, too small of a wire will have too much line loss and reduce the volts. I went from a #10awg to a #6awg with my 105A alternator and cleaned up the power terminations on the horn relay positive battery splice and had a 1.5 volt increase in the system voltage.

thanks for all your help. another problem that i am having and idk if it is related is that when i use my wipers they dont seat all the way back down when i turn them off and my windows need help going up and down (that may be the factory motors though)