Alternator -- 707HD chrys.

zopperman

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Hey guys, (Frank?)

How do i test my alternator with a multimeter? It's stock from '71! The PO told me it was running strong and he was really honest... but slightly insane so I'd like to check it before I get stranded. I've run the motor for a few hours with minimal accessories with no issue.. but I'd still liek to check it. Thanks, Zak :)
 

fucawi

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Re: Alternator -- 707HD chrys.

To check function put a voltmeter across the battery and when you have run for say 30 min it should have gone up to about 14.4v If its still at 12v then the alternator is not functioning and you need to ask us about how to test for a fault
 

zopperman

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Re: Alternator -- 707HD chrys.

Is there a way to test it without burning that much gas?
 

Nordin

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Re: Alternator -- 707HD chrys.

Put a voltmeter between the AC terminals at the rectifier. The voltage should start and raise when you rev up the engine. The alternator starts to charge at about 1000rpm and should have a output at maximum about 16-17 volts.
 

zopperman

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Re: Alternator -- 707HD chrys.

Whats a rectifier and where do I find it :confused:
 

Frank Acampora

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Re: Alternator -- 707HD chrys.

Your engine will either have a finned black aluminum box about 2 X 3 inches screwed onto the starter mount with three screws or it will have a 3 X 3 square finned red senelium rectifier.

You can put a VOM across the red terminal of the finned aluminum can and a ground and should see voltage.

For the seleniun rectifier, I think the center terminal is the pulsing DC. If your engine has a small aluminum can about 1 X3 inches, that is a trip regulator. check betweeen the red wire there and ground.

However, without a multimeter, you can still test. That elecronic ignition or battery and points ( if it still has them for ignition), uses a LOT of power. Simply disconnect the negative battery lead for a second while the engine is running. It won't hurt the electronic box and the engine will stall right away if the alternatior is not delivering power.

Practically speaking, if you start the engine and run it for about an hour on the water, if it will restart, the alternator has replaced the power used for the ignition and is working.

BTW: the engine in the avatar has a voltmeter on the dash. The voltmeter is about 1 volt off and reads lower than my vom. While running, the load from the electronic ignition and electronic distributor is so great that the meter reads 11 volts (actual 12) This is considered below the normal charging threshold. However, when stopped, even after extended running, the battery will read 12-12.5 on the dashboard voltmeter and 13-13.5 on the vom. The battery never runs down and the engine always starts.
 

zopperman

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Re: Alternator -- 707HD chrys.

Thanks Guys.. I'll test it by removing the battery terminal and report back. I have a white, painted, finned piece screwed onto the starter that has a purple ("generator") wire coming to it.. is that my alternator?
 

zopperman

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Re: Alternator -- 707HD chrys.

SO I did frank's test and the engine passed :eek: It ran without the ground connected. BUT, Now it's cranking, but won't start.. I still have spark... :confused: any chance I messed anything up, Frank?
 

fucawi

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Re: Alternator -- 707HD chrys.

whilst frank is at the top of his game I was very supprised to hear him say pull the neg lead off ..the induced voltage in the alternator IF the battery was charging is enough to damage the regualtor and its diodes and other electronics.....we will be interested to see what you find .....and please dont say done this hundreds of times with no problem ...been there heard that ....
 

Frank Acampora

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Re: Alternator -- 707HD chrys.

I did say only for a second. That CD ignition uses so much power that it keeps a load on the alternator and nothing will be harmed. I would not, however run the engine for hours or even minutes like that. And, I would not recommend this on later CD ignition systems with plastic boxes and multiple coils, even though the ignition is separate from charging circuits..

If you have spark at the correct time, gas, and compression, the engine MUST run.

Check to see if it is getting enough fuel to start and run. Squirt some pre-mix into the carbs and crank without choking it. If it is a fuel problem, as it clears out it should start then die. If you don't want to remove the airbox, then squirt into the plug holes and replace them. Again, crank until it clears itself. Not minutes, 10-15 seconds or so should do it
 

zopperman

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Re: Alternator -- 707HD chrys.

So I took the terminal off yesterday for LITERALLY less than a second. I was very nervous lol. I removed the plug #1 and checked for spark... I had it... I rebuild carbs last season so I didn't think it was a gas problem... I didn't want to remove the air box so I cleaned up the plugs and squirted oil in there. I tried starting it a bunch of times all to no avail... i generally don't have to choke the engine, but I tried starting it choked and I got some backfire... which it generally does before it starts (any way to fix that?) and then I tried again, choked, and it fired right up. Killed it and started it a few times. :D
 

zopperman

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Re: Alternator -- 707HD chrys.

Should I check for anything?? It did sound like it was idling pretty high.. but I need to adjust the points gap for the season and the low speed jets might be a bit off.. the manual recommends 1.5 turns, but I've found that it dies in idle sometimes... any ideas?
 

fucawi

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Re: Alternator -- 707HD chrys.

you will find that as you screw the idle needle in it goes faster then suddenly dies ...you want it at the peak of the rpm before it dies
 

zopperman

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Re: Alternator -- 707HD chrys.

Since I have 3 carbs, do i want to adjust one till it dies... then the next till it dies... then the last till it dies?
 

fucawi

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Re: Alternator -- 707HD chrys.

As you do each you will feel it start to stumble so you come back 1/8 turn ..do each carb ..some people have a tacho attached..make sure you have the opening of the carbs synced and start will all jets 1 1/2 out
 

zopperman

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Re: Alternator -- 707HD chrys.

Thanks, I'll post an update when I get a chance to play with it... it's pouring over here today
 
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