Originally Posted by Axl900
So heres my problem. I have only just started working on cars. so im not very car savvy. I started working on my dad's 78 firebird. it has a 402 in it and has been sittin for the last 8 years. i took the starter out and replaced all the spark plugs and when i put the starter back in after having it tested it makes a sound for about half a second then the car loses all power for a while. any help is greatly appreciated.
First thing I do when I begin on an old car is to get the factory service manuals for it. I'm not talking about Haynes or Clymer or other fosdick aftermarket manuals that are worthless in my opinion, I'm talking FACTORY manuals.
Here's the source I've used for many decades now......
1978 Pontiac Repair Shop Manual Original
I would suspect the electrical problem you're experiencing is due to bad grounds and bad cables. That's the second thing I do, replace all cables and also run some new ones. Most of these old hulks have a motor, body and frame, so I tie all three into each other. In your case, the car is a unibody design, lacking a frame, although it uses subframes front and rear that bolt into the body structure.
I would go back down to the auto parts place and get 3 new straps, positive, negative and ground.
Here's the positive battery cable:
NAPA AUTO PARTS
Here's the negative battery cable:
NAPA AUTO PARTS
Make certain that the connections for these cables are absolutely surgically clean of dirt, grease, paint and corrosion, down to bare metal.
Choose a bolt or a stud/nut on the motor somewhere that can be used as one end of a NEW ground strap connection point. Again, remove any paint, grease, dirt or corrosion, down to bare metal. Now, choose a place on the firewall of the body to anchor the other end of the new ground strap to. I like to use a place that I can get to from inside the body, like at the transmission tunnel or the footwell, so you can pull the carpet back from the firewall inside the car to tighten a nut. Also, you want to choose a place where there are no other components to disrupt, like a heater core
. What we're going to do is to sand down or grind down a bare metal spot on both sides of the firewall at the same location, about an inch and a half in diameter. We will drill a hole in the middle of the bare metal spot, about a 1/4" diameter hole will be good enough. Be absolutely certain that you know what's on both sides of the metal before you drill the hole.
We'll use a braided ground strap like this one.....
NAPA AUTO PARTS
Fender washers work well to hold these cables. You can find them at most any Ace Hardware in the bolt/nut section. They have a smaller hole in the middle than most other types of washers, so get several washers that have a 1/4" hole in them and that are big enough to cover the 5/8" hole in the ground strap. At the spot on the firewall, lay the cable end down against the firewall, cover the hole with 2 fender washers and insert a 1/4" bolt through the washers, strap hole and the hole in the firewall/floor. You will have the carpet pulled back so that your buddy can place a fender washer on the bolt from the inside of the car, then a nut on the bolt. With you holding the head of the bolt from the motor side of the firewall, your buddy will tighten the nut from his position inside the car. Now, use clear RTV to cover the nut and washer inside the car and the nut, washer and cable end on the firewall side of the car. You want to insure that water splashed up from the front tire will not get to your new connections at both the motor connection and the firewall connection.
If you chose the proper length bolt for the floor connection, there will be only a little bolt thread showing through the nut and it won't stick up and be a problem. That's why I like to drill the hole high up on the foot panel part of the floor, so that your foot doesn't feel the bolt shank. You can of course, do it the other way and feed the bolt into the hole from the inside, putting the nut on the outside. Whatever blows your skirt up.
Believe me, after this new cabling operation, you will have eliminated 99.9% of your electrical problems. Your gauges will be brightly lit and will operate properly too.
If you don't have any steel or bronze toothbrushes for cleaning parts, they are available at Walmart in the tools section. Buy a couple or three of each, they have a way of walking off. I always remove all bulbs as well, and clean the bulb connections as well as the housing connections.
Toothbrushes look like this and I have seen steel and bronze at Walmart.....