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ianmatt
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Group: Forum Members
Last Active: Last Year
Posts: 96,
Visits: 443
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This is driving me crazy. I am not a wiring / electrical guy at all. I did instal my tach and pertronix. For some reason when I turn on my lights my rpm drops by almost 200. Its not wanting to make my truck die. It didnt seem as bad before i swapped the eddy with the holly. Now I finally got the 600cfm Holley totally dial and this is happening. Where do i start? What could it be? Anyone have this problem? All I want to do is drive my truck.
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charliemccraney
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Group: Moderators
Last Active: Yesterday
Posts: 6.0K,
Visits: 385.9K
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Automatic or manual transmission? What is the voltage at the battery when it occurs? Does it happen at any rpm or only a particular range?
Lawrenceville, GA
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ianmatt
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Group: Forum Members
Last Active: Last Year
Posts: 96,
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manual, yes any rpm, much more noticeable at low idle. Reg idle is 650 and it will drop to 500 and below and want to die. I dont know what voltage is at battery. I know my mechanic said a while back that the battery was a battery for an RV and I should think about getting a different one but that it would work for now. I have never had battery problems. What is the battery of choice for a modified 292 with pertronix, cam, headers...?
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charliemccraney
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Group: Moderators
Last Active: Yesterday
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Regarding the battery, as long as your're not after a stock look, you want the battery with the most cold cranking amps that will fit. There is no go-to battery. What it sounds like is happening is that turning on the headlights is causing a significant voltage drop, which is affecting the ignition. So the first thing to do is to make sure that all grounds and connections are good. If the problem still exists, then next is to verify that the generator or alternator and battery are functioning correctly. An easy way to get an idea about this is to measure the voltage at the battery, one with everything off, another with everything on but the lights, and another with the lights.
Lawrenceville, GA
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62bigwindow
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Group: Forum Members
Last Active: 2 Months Ago
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I would look at the charging system first. Then the battery. Alternator or generator?
Durham Missouri
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ianmatt
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Group: Forum Members
Last Active: Last Year
Posts: 96,
Visits: 443
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Alternator is new. 6 months old and installed during engine build. I have always noticed a slight drop when lights are on however its as of recently its been lots worse. I wonder if i messed up a ground wire somewhere while swapping carbs. I may buy a new optima red top battery this evening and see what that does. Thanks for the help folks. I'll keep you posted.
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charliemccraney
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Group: Moderators
Last Active: Yesterday
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Check your grounds and do a voltage check before you spend money on a battery you might not need. I forgot to include that you should charge the battery before performing any of the tests. If the charging system is not working, the battery will be low, making it appear to be bad when it might not be. So put it on a charger to make sure it is fully charged then do your tests. If you have a shop manual, some of the tests may still be applicable even though it is no longer the stock generator. So have a look at the electrical trouble shooting section as well. If you have a shop manual for a newer vehicle with an alternator, that trouble shooting section may also help.
Lawrenceville, GA
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ianmatt
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Group: Forum Members
Last Active: Last Year
Posts: 96,
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I am curious if its possible for you to provide some specifics as to where to look / check the grounds? I am not good with electrical.
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charliemccraney
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Group: Moderators
Last Active: Yesterday
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I won't be much help with that. My truck has not been stock in that regard since I've had it. Even so, if yours is a different year or model it may not be the same. The negative battery cable goes somewhere, so that is one. There should be one from the block to the body or frame. Might be others. Which vehicle and year so others might be able to help?
Lawrenceville, GA
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MoonShadow
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Group: Forum Members
Last Active: 4 hours ago
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Are the alternator brackets powder coated or newly painted? The alternator ground through them and the block to the chassis. I would find all the ground straps and the negative cable connection and take them apart. Make sure the contact surfaces are metal to metal. Where is your battery mounted? If you don't find a ground connector on the block add one. Usually they bolt to one of the not used 3/8 bolts on the intake next to the accelerator linkage mount. Run a ground from there to a bolt on the firewall. I run my battery in the trunk of my Vicky. I used heavy gauge cable for the positive side and grounded to the frame at the rear. All connections were scraped for good contact. I see no drop in the charging circuit tested at the alternator and at the battery.
Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.
 
MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire
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