The Ford Barn

30Tudor · 08-18-2010, 08:39 PM

I have an alternator on my car - yes I know I don't need it relative to a good performing generator. However, I am curious about why the pulley needs to be so small. I haven't done the math, however, the alternator would be spinning at a very high speed at cruising speed. What RPM do they need to kick in?

josh1331 · 08-18-2010, 09:36 PM

I changed to alternator used the same pulley no problem at all. /Josh (I did put on new pulley to start off fresh.)

Gord. B by the bay · 08-18-2010, 10:01 PM

I use a 2" pulley with no problem Gord. B

CCWKen · 08-18-2010, 10:36 PM

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Alternators vary depending on type. It can be from 800 to 1000 rpm before they "kick-in" or start producing DC current. This would be alternator rpm, not engine rpm. I wouldn't worry about the upper limit. You won't reach it in Model A.

08-18-2010, 08:39 PM	#1
30Tudor Senior Member Join Date: May 2010 Location: Calgary, Alberta, Canada Posts: 211	Alternator Pulley Size? I have an alternator on my car - yes I know I don't need it relative to a good performing generator. However, I am curious about why the pulley needs to be so small. I haven't done the math, however, the alternator would be spinning at a very high speed at cruising speed. What RPM do they need to kick in?

08-18-2010, 09:36 PM	#2
josh1331 Senior Member Join Date: May 2010 Location: Charlestown,R.I. Posts: 465	Re: Alternator Pulley Size? I changed to alternator used the same pulley no problem at all. /Josh (I did put on new pulley to start off fresh.)

08-18-2010, 10:01 PM	#3
Gord. B by the bay Senior Member Join Date: May 2010 Location: Owen Sound Ont. Canada Posts: 198	Re: Alternator Pulley Size? I use a 2" pulley with no problem Gord. B

08-18-2010, 10:36 PM	#4
CCWKen Member Join Date: May 2010 Location: South Texas Posts: 97	Re: Alternator Pulley Size? Sponsored Links (Register now to hide all advertisements) Alternators vary depending on type. It can be from 800 to 1000 rpm before they "kick-in" or start producing DC current. This would be alternator rpm, not engine rpm. I wouldn't worry about the upper limit. You won't reach it in Model A.