Where to Start
Before you even think about cutting that block of wood, you first need to decide where you want your weight to go. Your plans should be thought out carefully and have a design in mind before cutting. You want to drill any holes or machine any wood out before you cut the shape, if you can. When drilling, especially if you happen to have a drill press, it is much easier to drill when the block is still square. The biggest obstacle is to know where to drill or for that matter to put your weight.
If you search the internet, and I suggest maximum-velocity.com, you will be able to find some diagrams of cars for free or of course you can also purchase them as well. Maximum Velocity will send you complete car plans for one of their models for free if you just sign up to get their free emails. Their plans tell you exactly where to put the weight, how much and what kind.
If you can't find car plans you like, here are some tips on where to put your weight.
For a basic wedge it is best to drill two holes towards the rear of the car on the side with a brad point drill bit, I suggest a 7/16ths bit. Use a pencil or fine tipped magic marker to trace out your wedge car so you will see where you need to drill, mark the rear of the car. Make sure you have enough space to drill the holes - this is why I recommend drilling first and cutting later. Tracing out the car will give you an idea on how well you can place your weight. You will want to drill one hole in front of the rear axle and one behind the rear axle(centered between top & bottom of car) and go 1-1/2 inch deep. You can measure the drill bit from the outside cutting edge and then put tape on the bit where it measures 1-1/2 inches so you will know when to stop drilling into the wooden block. Using 3/8" lead rod, you will want to cut four 11/16" pieces of lead so you can put 2 pieces into each hole. You will need to use a hammer to shape the lead and make both fit tightly into the holes. You should have about 1/4" left over to install a 7/16" piece of dowell rod using glue to fill in the hole. Then cut and sand the two dowells to smooth them to the shape of the body.
You will then want to drill some holes in the bottom of the car for balance. Put the car with the bottom up and measure from the rear of the block. You will want to drill 3 holes, using the 7/16" brad point bit, in one row from side to side. For extended wheel base measure all 3 holes1-5/8 inches from the rear of the block to the center of the drill bit. Center the middle hole (drill it first) and then even the other two out with it on each side of center hole. For standard wheel base measure all 3 holes 2-1/4 inches from the rear of the block to the center of the drill bit. Drill each hole in the bottom 7/16" deep regardless of standard or extended wheel base. Put some elmers glue and a 1/2" long piece of 3/8" lead rod into each hole on the bottom of the car. Allow the glue to dry before working on the car from this point.
The weight setup described above will give you a grea setup for a standard wedge car. The center of gravity for your car should be around 3/4" in front of the rear axle. This helps the car on take off and keeps it going on the straight-away.
Putting the weight too far back might make your car pop up and maybe even off the track when it comes to the curve on the track, but putting it too far up front will make it slow down on the straight-away. The most common center of gravity point on the car is 3/4" in front of the rear axle. Use a ruler and put it on edge and then try to balance your car on the ruler to see where your center of gravity is. Some call this center of mass also.
You may be overweight when you completely finish the car, if that happens you can drill out some from the bottom of the car to bring it back down to 5 ounces. Just make sure you hold the car and the drill so lead pieces don't get into the wheels. The best thing to do is to actually have it a little overweight when you take it to the races and make sure you bring a drill with you so you can bring it down using their scale. Most race officials have a drill or dremel tool on hand to take care of this for the boys, but don't count on anything, I have a complete tool box that I take with me just in case.