I'm not the electronics guy. I'd propose running it straight to the tach. A ballast resistor will kill the signal pulse, that won't work I don't think.
All Small Six Weber 32/36 rough idle
- Thread starter beanmiester
- Start date
This relates to all small sixes
On the topic of electricity, what amp alternator are you guys running? This 95 amp(?) One i have doesn't produce enough power at idle
If you don't have enough amperage at idle, it's not the alternator. I'm still running the stock 55 Amp alternator. No air conditioning so it doesn't have a ton of draw but my halogen bulbs pull about an added 10 - 15 amps and I have no problem at idle with the lights on, wipers on, etc...
Ah. Maybe my idle is dipping or something? I have it set to 500 because that's what the manual said. I had it at 800 at one point and it still would lose voltage at stoplights. Its fine in park though
500 is probably a bit on the low side, especially for an auto transmission. I've recently set mine (with a manual transmission) a bit on the high side. I warmed it up, tuned on the headlamps and heater and set the idle to be smooth. It's somewhere around 500 - 750 maybe. It's higher in the day with the headlamps off and the heater off but that's the tradeoff. Since mine is manual, it has no real drag on the flywheel the way an auto does.
I'd probably set yours so that it's around 500 in drive at a stop with the headlamps on, etc...
Curious to know if you do have a 95 amp alt. I expect to go to the 3G 95 amp alt as it is supposed to put out more amps at low rpm than the old 1G 55 amp like I have now. The 3g was used on many vehicles like Aerostar, Taurus etc with injection, ac and other electric loads far greater than old Mustangs and Broncos.
I belive that's what I have. I did it a year ago and the alternator is unmarked. I know its more than what was originally on it. After driving for a few minutes If I stop in drive the voltage goes to like 11. Driving everything is fine but I can't even have my blinker on without a big voltage drop at idle in drive. I even had the rpm at 900 in park and would have the same issue in drive. The engine would almost stall sometimes if the light was too long like the distributor wasn't getting enough power. It was like a progressive stuttering until the engine would just stop. Throw it in park and give it a tiny bit of gas and it was all good. The transmission has been checked by 3 separate places so I know its not binding. Im hoping when I install the dui it might fix it since it will get power directly from the battery and won't really go through the harness
Possible pulley is incorrect size from original 3G 95 amp on more modern vehicle?
Technically its for a gm but the guy at Napa uses them in his mustang he restored. The only difference between the old and new one appearance wise was the mounting holes. I had to drill them out slightly.
I saw an advert for a GM alternator last week (Facebook Marketplace) where the seller mentioned that at idle it doesn't put out any voltage. I wonder if that is a weird quirk of some GM alternators. A smaller pulley on the alternator would spin it faster at idle and might fix that issue.
What is the maximum voltage you get out of it at 2500?
I couldn't tell you at that specific rpm but ballpark rpm, I've never seen voltage go above 13 ish
That's not good. Optimal voltage for charging is between 13.8V and 14.8V. Are you sure it's not going above 13-ish?
13.5 maximum
I would do voltage checks both at the battery and on the alternator, see if there is a difference
Not a bad idea and use a proper volt meter. If it's getting somewhere around 13.8v at the battery and not at the dash then you can check your grounds as they're the most likely culprit and then the rest of the harness if that's not the problem.
The battery was reading 12.5. I had the autozone guys check it and it tested good. When running my sears analyzer says the charging circuit makes 14 when running and 12.5 when not. I don't think things are getting the full 14 though because when the electric fan kicks on it reads 12.5 and any other things running sends it over the edge to 11. I know the harness in the dash is fine. I checked everything when installing my rally pac. Very confusing for me because it shouldn't dip so bad if everything is working right
The alternator cable is 4 gauge going onto the battery side of the solenoid btw. The cord is like 3 feet long if that
Is the voltage output the same at the back of the alternator as the reading you get at the battery?
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