Posted March 23, 200222 yr comment_4439 Ok i know this is a question straight out of newb central but it's been on my mind for a while and you are the guys to answer it. When i fire up my 240 i notice that the lights although bright are dim compaired to when i rev the engine up. Also the wipers are slow until i hit the gas. Now i know that the faster the engine turns the more power the alternator puts out, but why do i not get the same power at idle. My other cars (30 yrs younger) have no disparity in power from idle to higher rpm's. Is this common with early Z's or do i have a slight problem that needs to be addressed. The alternator is brand new and so is the coil. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/ Share on other sites More sharing options...
March 23, 200222 yr comment_4441 It is possibly the voltage regulator that needs to replaced. The alternator should put out pretty close to the same voltage all the time, it's the voltage regulator that controls the output to the battery and various systems. They can be adjusted but most people just replace them as they are not expensive. You can probably pick one up at Pep Boys etc. for under 20 dollars. Try that and see if that helps. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4441 Share on other sites More sharing options...
March 23, 200222 yr comment_4442 Welcome the 240! Y ou have just ask the same first question we all did.The more rpm the brighter is a 240 thing.The specs for the alternator show it 's charging ability begins at 1000 rpms.You could increase your idle.Thats to high for me.I do have a theory I'm working on.I believe you could change the pully on the alt. to increase it's rpm without the cars rpm increasing. Daniel Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4442 Share on other sites More sharing options...
March 24, 200222 yr comment_4490 Well,my pulley swap theory is no good.Seems if you swap the pulley making the alt. faster that in turn increases the strength of the magnetic field within the alt. That in turn puts more load on the engine which would effect your idle.Also having the additional load at idle could cause the alt. belt to slip as rpm's increased.There are other issues I won't bore you with.The bottom line is the alt.s magnetic field acts sort of like a clutch on a kids go cart and once again you need to think long and hard about trying to outsmart the datsun engineers.They know. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4490 Share on other sites More sharing options...
March 25, 200222 yr comment_4512 Dan, My Z does the same thing. I'm putting in a new VR on Tuesday. If this solves the problem I'll let you know. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4512 Share on other sites More sharing options...
March 25, 200222 yr Author comment_4514 Thanks Ed i'd be glad to hear what happens. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4514 Share on other sites More sharing options...
March 25, 200222 yr comment_4515 Hey Dan, RU going to the Motorsports Z show May 5th? CU there. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4515 Share on other sites More sharing options...
March 25, 200222 yr Author comment_4516 Yep i wouldn't miss it. I will be taking my humble 240 up there although i'm not going to show it. I think that go z racer and i will try and drive up there for a day. If you would like to drive up there also i think it would be a laugh to get a train of Z's on the highway for the trip. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4516 Share on other sites More sharing options...
April 1, 200222 yr comment_4831 I have noticed the same thing with my 240Z. I am even running a '81 L28 and it does the same thing. When I asked around (at length) I found that this was a 240Z thingie. According to some old Z nuts I talked to in Illinois, the 240Z alternator is acutally not a alternator at all but rather a generator. Why the difference is slim, the faster it turns the more power it cranks out. I changed out my voltage regulator and same thing happens. [puzzled look] I suppose that it really is not a big deal since it is usually over 1000 RPM when driving anyway. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-4831 Share on other sites More sharing options...
April 9, 200222 yr comment_5200 I put in a new battery and a new V.R. It still does the dimming thing below 1000 rpm. Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-5200 Share on other sites More sharing options...
April 9, 200222 yr comment_5204 Thats just what they do.The charge and discharge just about breaks even at less than 1000 rpm,s.I'm just glad you got yours repaired before any real damage occured and without injury!! Daniel Link to comment https://www.classiczcars.com/forums/topic/1166-electrical-question/#findComment-5204 Share on other sites More sharing options...
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