I recently added March Performance alternater 20120 and PS 20160 brackets to my 69 camaro. For some reason I couldn't get the alternator belt to work correctly with the new alternator bracket and the stock v belt pulleys. March told me these brackets were orginally designed for the long water pump small block 2 belt serpentine system, so I went ahead and ordered my serpentine pulleys since I was going to get them in the future anyway. I ordered kit 6330 and the 616 ps steering pulley. I fired up the 69 and my pulley alignment issues are gone. No more squealing or smoking belts. I did notice that when the choke shut off and the car idled around 800rpm, my voltage was just a little higher than 12volts. Is that normal with the performance series serpentine pulleys? I have 100amp powermaster alternator in the one wire setup. I just replaced my front light harness with Autowire Factory Fit kit from Ricks. Am I going to have charging issues?
Added March Serpentine pulleys idle voltage is around 12 volts
DenRS
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I recently added March Performance alternater 20120 and PS 20160 brackets to my 69 camaro. For some reason I couldn't get the alternator belt to work correctly with the new alternator bracket and the stock v belt pulleys. March told me these brackets were orginally designed for the long water pump small block 2 belt serpentine system, so I went ahead and ordered my serpentine pulleys since I was going to get them in the future anyway. I ordered kit 6330 and the 616 ps steering pulley. I fired up the 69 and my pulley alignment issues are gone. No more squealing or smoking belts. I did notice that when the choke shut off and the car idled around 800rpm, my voltage was just a little higher than 12volts. Is that normal with the performance series serpentine pulleys? I have 100amp powermaster alternator in the one wire setup. I just replaced my front light harness with Autowire Factory Fit kit from Ricks. Am I going to have charging issues?
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The voltage read can be affected by where the meter is attached, as well as pulley ratio's / speed of the alternator, and losses in wiring and connections. Idle reading may also be abnormaly low if the alternator is working hard, that is the battery charge level is low at that time.
Is your voltmeter installed in the dash?
Is the reading DIFFERENT that the same meter read under the same conditions before the changes?
If yes, I'd "walk" a handheld digital voltmeter down the system under the hood. At the battery, the alternator, the horn relay, and under the dash.
I'd also see what the voltage does at higher rpm (1000-1200-1600) and at different loads (turn on the headlights and crank up the stereo)
A reading of 12 volts and change at the alternator at an 800 rpm idle would not bother me if it came up to 13.8 or more by 12-1400 rpm, and if that voltage at idle did not drop (more than a tenth or two) when the headlights were switched on, and if the system was able to produce 13.8 or more volts with the headlights on at 12-1400 rpm.
Is your voltmeter installed in the dash?
Is the reading DIFFERENT that the same meter read under the same conditions before the changes?
If yes, I'd "walk" a handheld digital voltmeter down the system under the hood. At the battery, the alternator, the horn relay, and under the dash.
I'd also see what the voltage does at higher rpm (1000-1200-1600) and at different loads (turn on the headlights and crank up the stereo)
A reading of 12 volts and change at the alternator at an 800 rpm idle would not bother me if it came up to 13.8 or more by 12-1400 rpm, and if that voltage at idle did not drop (more than a tenth or two) when the headlights were switched on, and if the system was able to produce 13.8 or more volts with the headlights on at 12-1400 rpm.
Had the same setup problem. Like Jim said, your ratio has been changed with the performace setup. March sells a smaller alternator pulley that will bring your ratio back where it needs to be to keep it charging at idle, especially if you have electric fans and air. I can get you the number if needed but it worked great on my setup. I was using a 1 wire 140A alt.
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762 Posts
madmax87, I have the same setup with my big block and the same problem. Nice to know there is a easy fix. What's the part number for the pulley? I'll have to look into getting one.
My voltage reading was taken using the autometer gauge in the dash. My gauge is fairly new. When I installed it a few years back it was dead on. My voltage was higher before I changed over to the under drive pulleys. I don't remember what it was before the swap, but it was a little higher at idle. When I drove the car yesterday, it went up to 13.5 volts. I'll check the voltage with the headlights on today.
I may go with the new alt pulley if necessary. Madmax, can you give me the part number?
I may go with the new alt pulley if necessary. Madmax, can you give me the part number?
March p/n is 112. This is the Ultra finish, 6 groove serpentine, 1-11/16" dia. Polished billet with clear powercoat like in the pic above.
Order thru Jegs p/n 655-112, $49.99. Comes with cover.
Order thru Summit p/n MCH-112, $49.88. Comes with cover.
Order thru Jegs p/n 655-112, $49.99. Comes with cover.
Order thru Summit p/n MCH-112, $49.88. Comes with cover.
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Thanks for the part number, now I just need to find a smaller belt.
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.....Or you could get a longer tensioner rod for your alternator. They are also available from March Performance.
David F.
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My March ultra runs about 13.2
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I picked up the March 112 Pulley and a smaller belt. It finally puts out 14 volts at an idle.
Had the same setup problem. Like Jim said, your ratio has been changed with the performace setup. March sells a smaller alternator pulley that will bring your ratio back where it needs to be to keep it charging at idle, especially if you have electric fans and air. I can get you the number if needed but it worked great on my setup. I was using a 1 wire 140A alt.
![Image]()
Ditto... I had the exact same problem I went with the smallest alt pulley and my volts never go below 14.1 even with the fans on.
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8,305 Posts
this is one reason to stick with the GM pulleys whenever possible.
Dennis,Had the same setup problem. Like Jim said, your ratio has been changed with the performace setup. March sells a smaller alternator pulley that will bring your ratio back where it needs to be to keep it charging at idle, especially if you have electric fans and air. I can get you the number if needed but it worked great on my setup. I was using a 1 wire 140A alt.
![Image]()
That is a clean engine compartment.
But please do us all a favor and get rid of that rubber fuel line.
Unfortunately that 69 is no longer with us but the engine was salvaged and put into my new project and yes "stainlesss lines" added.
Unfortunately that 69 is no longer with us but the engine was salvaged and put into my new project and yes "stainlesss lines" added.
![Image]()
Good good. I'd hate to see anyone lose a car to fire when it's easily preventable.
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