guys,

Well, i fired up my 540 BBC today. all kinds of goodies and i built it myself! :)

but, i had a couple issues. most are no big deal at all, but one issue i have is that when my dual spal fans (part of the becool radiator stuff) kick on, the car seems like it wants to die. idle goes from 800 to maybe 600 and then it will die if i let it.

this only happens when the fans kick on. headlights no problem.

my first guess is that the fans are drawing a lot of current and that might make the voltage at the coil drop a big, but my friend measured the voltage across the battery and its roughly 14.3 volts w/o fans and 13.5 with fans. is that a clue?

any other ideas?

thanks guys
jeff

I have that issue on mine, I have to set the idle up high enough to make it live with the fans on. I think it's the extra draw in the alternator slowing the motor down.
I have plans for: 1) a CS style alternator and 2) a Spal fan controller.

i have the CS alternator already. i think thats what its called. i think its a 93 Chevy truck alternator. internally regulated. real nice.

i had these fans and alternator on my old motor and it never seemed to do it.

hmmmm ... can anyone else help us??

These big fans on all these radiators do that. It is common for them to pull the idle down, especially at a reaL low idle. The lower the idle, the worse the affect. Some fan set ups pull 40 AMPS, which is a lot seeing as the car may have originally only had a 37 AMP alternator to run the entire car! Now I know you have a late model alternator, but your alternator may not be turing on at low RPMs so your trying to run the fans on battery power, and your sucking the life out of them if they alternator is not putting out at Idle, which is probably the main problem. Why do you have it idling so low? Bumping it to 950 may make a huge difference in what the alternator is putting out at idle and will probably not be as affected by the fans. But with these monster fans and all the electrical crap we put in these cars, we usually do 2 batteries to double the amps.

Try a dual fan controller so it doesn't turn on both fans the same time on high. It's a big draw all at once. The spal controller turns on one fan slow then raises the speed untill the high is set then the second fan comes on full. I't much easier on the alt and engine.

its just kinda funny that i dont remember this stuff happening on my other motor, but its been a year and a half since i last drover the car. maybe i dont remember.

ill call them today and see what i can get...

thanks guys