427 SO Timing/cooling fans

[McD00]

Originally Posted by For Paw

Thanks for all the advice. Just to set the record straight, the wiring has been done with the best of breed components-everything from 0 gauge non-oxidising bat cables used in high end audio applications run directly to the Alt, ground run right to the block/starter, to all the ground straps one could think of to mig welded ground bolts on the chassis. I have had great advice from the best in the industry and have followed their advice and double checked to make sure that i have not missed anything. The carbs have been tuned within an inch of their miserable lives, and I am as close to the sweet spot as possible without going to a Dyno (These are going to be replaced by a Weber Stack system over the winter once I get this idle issue solved) So I have chased this on and off for over a year now and everything keeps pointing to the Alt. I guess MSD like any other manufacturer can goof every once in a while.

I have decided to order a new Reactor 100A alt to replace the MSD 105A I had. The main difference in the two is that the Reactor deliver full capacity at 1450 rpm vs MDS at 3000 and delivers more at 1000 rpm (idle for my engine) than any 1 wire on the market. I plan on measuring all the outputs once I get my parts and install them.

Rick, Alt output is 14.7. In one of my tests I unhooked the alt wire before starting and I did not have the problem when the fans kicked in. It might be something as simple as this Alt is malfunctioning. I have a 6.5 crank and larger water pump. I don't want to start changing Pulley ratios as this could start a chain reaction of water pump and cooling problems. The engine has been built to my specs by Southern Auto and they seem to know their stuff and have done these for many years now. This is a problem I have caused-I should have used their 65A alt supplied but i did not like the 3 wire system appearance and wanted something more advanced-that is pretty much where all this began. I did not realize that the 3000 rpm kick in on the MSD would be a problem. I am still holding that Alt ready to go if the Reactor does not work. All I need to do is get a voltage regulator or convert that to a one-wire. We'll see soon enough.

Randy

Are you running a amp gauge? Sometimes they limit your current flow. I run a
regular ford 65 amp alternator and it powers my fans,lights and msd at the same time no problems. Sometimes all these fancy pants alternators are not the way to go.
Shelby just used a regular alternator and if it's good enough for him it's good enough for me.

Long live the Cobra!!

[undy]

nudder thing.....

Most fan manufacturers rate their fan CFMs above battery voltage. Spal, as listed here, rate theirs @ 13.0 volts. I believe Flex-a-Lite rates theirs even higher. If you have an "undersized" alternator that goes into discharge at idle then your electric fan isn't providing it's rated CFM. If you're driving the typical "cooling challenged" Cobra, that's not a good thing. With everything on my alternator provides a constant 14 volts, at the battery OR the fan. If your car's wiring "infrastructure" is also inadequate, which a LOT are, then the problem's compounded. With your car running, at idle, run a voltage test at the cooling fan. A lot of people would be suprised. With my Lone Star's painless harness and provided 65 amp alternator I was getting 10.2 volts to my cooling fan till I rewired the whole circuit.

Dave

http://www.spalusa.com/fans/automate.../1516-1517.pdf