Ford vs Chevy Build-up - Page 51

HandOverFist · 05-30-2015, 01:19 AM

Quote:

Originally Posted by Sean Marconette

Rich,
What brand alternator do you have? My East Coast Electric has a small pulley and a 4.5" pulley on the crank. It see's over 7000 engine RPM for the last 7 seasons on every pass without issue. The alternator should be self regulating regardless of RPM. What gauge of wire did you use from the alt to the battery?

Sean

This one Sean... http://www.jegs.com/i/JEGS-Performan...oductId=752892

The set-up as run...

Just grasping at straws here. I did not have any 10 gauge wire on hand so I paralleled two 12 gauge wires to the battery positive and a short 10 gauge ground from the alternator case to a head.

Edit: Just re-read the instructions and it states no Jegs alternators are designed to to be spun beyond 15,000rpm (6000 engine rpm).

I can try it one more time with a large crank pulley or purchase another brand alternator. At this juncture I just want one that works without worry.

Bob Mulry · 05-30-2015, 04:03 AM

Quote:

Originally Posted by HandOverFist

This one Sean... http://www.jegs.com/i/JEGS-Performan...oductId=752892

The set-up as run...

Just grasping at straws here. I did not have any 10 gauge wire on hand so I paralleled two 12 gauge wires to the battery positive and a short 10 gauge ground from the alternator case to a head.

Edit: Just re-read the instructions and it states no Jegs alternators are designed to to be spun beyond 15,000rpm (6000 engine rpm).

I can try it one more time with a large crank pulley or purchase another brand alternator. At this juncture I just want one that works without worry.

Just a heads up....

I think that you have it backwards....

Big crank pulley & small alternator pulley = overdrive

Small crank pulley & large alternator pulley = under-drive

4" crank pulley with 2" alt pulley at 7,000 rpm engine RPM = 14,000 alternator RPM

2" crank pulley with 4" alt pulley at 7,000 rpm engine RPM = 3,500 alternator RPM

Hope this makes sense to you and helps......

Bob

Tony Corley · 05-30-2015, 08:24 AM

As stated above, the small crank pulley slows it down.

HandOverFist · 05-30-2015, 08:42 AM

You know, that is what I thought as well but I let someone talk me into that one lol. With that out of the way I can see no reason for two failures in a row other than these alternators are junk.

FireSale · 05-30-2015, 11:10 AM

Quote:

Originally Posted by HandOverFist

You know, that is what I thought as well but I let someone talk me into that one lol. With that out of the way I can see no reason for two failures in a row other than these alternators are junk.

This may be true. I had a Powermaster that wouldn't charge my Optima so I replaced it with a 140 amp Tuff Stuff connected as a one wire. It worked fine then went haywire and put out 44 volts to the battery. I popped the cover to the two terminals for a three wire hookup and jumped one to the battery output on the alternator based on something I read on the Internet. Makes little sense to me but it works now. Whatever internally activates the regulator crapped out, I guess.

Dale

jcw31 · 05-30-2015, 01:25 PM

Rich a one wire alt. has to turn around 2000 rpm to excite it for it to start charging. Once it starts charging it stays until you shut off the engine

Joe

HandOverFist · 05-30-2015, 04:47 PM

Quote:

Originally Posted by jcw31

Rich a one wire alt. has to turn around 2000 rpm to excite it for it to start charging. Once it starts charging it stays until you shut off the engine

Joe

This one excites at 880rpm...when its working. http://www.jegs.com/i/JEGS-Performan...oductId=752892

Sean Marconette · 05-30-2015, 09:48 PM

Bob is right on. That crank pulley has to be close to 3.5", if the alt pulley is 2", that calculates to 12,250 at 7000 RPM. At 1000 RPM the alt is only at 1750 RPM.
Will the alt produce any voltage if you increase the engine RPM to 2000 or 3000?

Sean

HandOverFist · 05-30-2015, 10:22 PM

Quote:

Originally Posted by Sean Marconette

Bob is right on. That crank pulley has to be close to 3.5", if the alt pulley is 2", that calculates to 12,250 at 7000 RPM. At 1000 RPM the alt is only at 1750 RPM.
Will the alt produce any voltage if you increase the engine RPM to 2000 or 3000?

Sean

From the beginning both alternators worked fine, even at idle. I guess they lasted part of one stint each at the track when I realized they were no longer charging. You can wing it to six grand if you like...it aint happening. Something inside the alternator is just not holding up it's end of the bargain.

Alan Nyhus · 05-31-2015, 09:41 AM

Just went through a similar issue. The one wire alternator didn't excite until 2500 alternator rpm. With the combination of a large alternator pulley and small crank pulley, there wasn't a lot of time that the alternator was putting anything back into the battery. To make things worse, the alternator had a bad diode and rectifier so it was only putting out 15 amps when it was charging.

Had it rebuilt and now it works fine.

Changed the charging system to a larger 74 amp constant output alternator with a 6" crank pulley. The excite power wire runs through a heavy duty toggle switch on the dash so the alternator can be turned off during a run. -Al

05-30-2015, 08:24 AM	#503
Tony Corley Member Join Date: Nov 2011 Posts: 264 Likes: 42 Liked 61 Times in 25 Posts	Re: Ford vs Chevy Build-up As stated above, the small crank pulley slows it down.

05-30-2015, 08:42 AM	#504
HandOverFist VIP Member Join Date: Oct 2013 Location: Gulf Breeze, FL Posts: 1,651 Likes: 8 Liked 33 Times in 16 Posts	Re: Ford vs Chevy Build-up You know, that is what I thought as well but I let someone talk me into that one lol. With that out of the way I can see no reason for two failures in a row other than these alternators are junk. __________________ Rich Taylor I/SA - 321

05-30-2015, 01:25 PM	#506
jcw31 Junior Member Join Date: Jan 2013 Posts: 94 Likes: 0 Liked 6 Times in 6 Posts	Re: Ford vs Chevy Build-up Rich a one wire alt. has to turn around 2000 rpm to excite it for it to start charging. Once it starts charging it stays until you shut off the engine Joe

05-30-2015, 09:48 PM	#508
Sean Marconette Senior Member Join Date: Mar 2006 Posts: 977 Likes: 796 Liked 275 Times in 76 Posts	Re: Ford vs Chevy Build-up Bob is right on. That crank pulley has to be close to 3.5", if the alt pulley is 2", that calculates to 12,250 at 7000 RPM. At 1000 RPM the alt is only at 1750 RPM. Will the alt produce any voltage if you increase the engine RPM to 2000 or 3000? Sean __________________ Sean Marconette 84 Mustang 5060 SS/N

05-31-2015, 09:41 AM	#510
Alan Nyhus VIP Member Join Date: Dec 2002 Location: Lower Dakota territory Posts: 1,180 Likes: 1,074 Liked 799 Times in 236 Posts	Re: Ford vs Chevy Build-up Just went through a similar issue. The one wire alternator didn't excite until 2500 alternator rpm. With the combination of a large alternator pulley and small crank pulley, there wasn't a lot of time that the alternator was putting anything back into the battery. To make things worse, the alternator had a bad diode and rectifier so it was only putting out 15 amps when it was charging. Had it rebuilt and now it works fine. Changed the charging system to a larger 74 amp constant output alternator with a 6" crank pulley. The excite power wire runs through a heavy duty toggle switch on the dash so the alternator can be turned off during a run. -Al __________________ "That'll never work....."