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jkh04200
09-24-2007, 10:11 AM
84 Chris Craft with a 305 I/O , Thunderbolt ignition. Book shows alt. should put out between 13.8V & 14.5V. Mine is at 13.14. I checked it at the alternator and at the battery while running. Can't this hurt performance?
DelawareDave
09-24-2007, 11:34 AM
What does the battery read when not running? If your battery is fully charged, your alternator is probably OK. The output voltage should have no effect on performance, unless it isn't charging at all, and your battery is dying.
jkh04200
09-24-2007, 11:56 AM
Battery is fine. 12.7V But, with this low of voltage wouldn't the spark at the plug be lower than desired?
jkh04200
09-24-2007, 12:22 PM
The alt. does have an adjustable regulator. At one time it was charging to high and actually boiled the battery
DelawareDave
09-24-2007, 01:00 PM
The electronics are designed to operate correctly in a certain voltage range. As long as your system meets that criteria, you will be ok. 12.7 off, 13.14 running is within that range.
SmokinLowriderSS
09-24-2007, 03:40 PM
I don't think 13.1v is going to matter much, although it is lower than normal.
Does it hold 13.1 with every possible accessory turned on? That is the most important part.
jkh04200
09-24-2007, 06:11 PM
Thanks, but wouldn't I have a weaker than normal spark at the plugs when the book shows 13.8 min and 14.5 max? The plugs look rich to me and it is very rich at idle, it will die at times and I have to "floor" it to get it started.
DelawareDave
09-25-2007, 01:21 AM
Thanks, but wouldn't I have a weaker than normal spark at the plugs when the book shows 13.8 min and 14.5 max? The plugs look rich to me and it is very rich at idle, it will die at times and I have to "floor" it to get it started.
Your alternator is NOT causing your engine to run rich. Yes the output is a bit lower than normal, but it will not cause the symptoms you are describing. It sounds like you may have a flooding carb to me.
Jetaholic
09-25-2007, 02:02 AM
The important thing is...is it charging?
Yes that may be lower than normal. However, normally the voltage across the battery should be between 13 - 15VDC, and it would increase slightly with RPM. If the alternator were not working, it would do just the opposite...decrease with an RPM increase. This is because at a higher RPM, the engine puts an increased load on the battery, causing the voltage drop. With the alternator working, it would increase with engine RPM because of the increased alternator RPM.
jkh04200
09-25-2007, 06:50 AM
Yes, I know the Alt. is not causing it to run rich. But, if you have a weak spark it could keep the plugs from showing true color.
Bondo
09-25-2007, 03:03 PM
Yes, I know the Alt. is not causing it to run rich. But, if you have a weak spark it could keep the plugs from showing true color.
The answer to this question is NO........
Fix the Carb to get the plugs looking Better.....
And,........
If the regulator is Adjustable,....... Bring it up to 13.6V / 13.8V........
But,.......
It Ain't going to change the burn of the Plugs..........