I have a 73 wagon with stock 2.0, 4 speed trans. I added pertronix ign, opened up the primary jet in the stock carb a few thousands of an inch which made a considerable difference. The biggest improvement came from advancing the cam about 4 degrees and eliminating the vacuum advance and setting the timing at about 12-13 degrees initial at 1000 rpm. This made a world of difference in torque even with the 8.2 compression.
I tried a $170 ALUMINUM Kent cam adjustable cam pulley and it worked well for about 5k miles then the teeth wore out.
I found that if you take a stock steel cam pulley you can offset the keyway about .075 to achieve about a 4.5 degree cam advance.
I did this by widening the keyway by filing it and inserting a .075 shim made from a finishing nail.
The metal in the pulley is surprizingly soft and with a good file you can widen the keyway in about 20 minutes of filing.
With the keyway widened, i made a shim from a steel finishing nail with a dia of .075, presto.. 4.5 degrees cam advance. 0 dollars about an hour of work.
If you want to try this i recommend finding a spare stock pulley to work on so you have the original if you screw something up.
Before you start, position the timing marks on the crankshafy pulley at tdc and the rotor in the distributor is pointed at the tcd mark on the distributor housing.
Then make a mark with a hacksaw in the sheetmetal backing plate wheel behind the cam pulley as detailed in Figure 1. (Hacksaw is yellow )
Make the mark in alignment with the center rib on the valve cover. This makes it easy to realign the belt at the right timing and can as well be used to position the engine at tdc in the future.
note that the front side of the pulley has three raised blobs (figure 3 Blue arrows) , Mark the front side of the pulley with paint to make it easier to identify which side goes toward the front when you replace it.
Loosen the cam pulley bolt and check to make sure you havent moved the cramk from tdc. If it has moved, realign the crank to tdc and make sure the mark made in the pulley backing plate is alighed with the rib in the cam cover.
Untension the belt adjuster as you would when changing the belt and slip the belt off just the cam pulley making sure that it is still positioned on the crank and distributor pulleys.
Remove the cam pulley without moving the cramkshaft and cam position.
Scribe marks on the pulley on each side of the original keyway and put a dot of paint at the location of the original keyway for future reference. Figure 3 red arrow
Clamp the pulley in a vice or hold it facing you as it did when on the car with your paint mark facing you and with the keyway on the right side (at 3 oclock) as shown in Figure 2.
With the pulley facing you the way it sits on the cam, with your paint mark facing you, and the keyway at 3 o'clock, carefully file the BOTTOM EDGE (toward 4 o'clock) of the keyway and widen the keyway about .080 to .090" as shown in Figure 3. yellow arrow
periodically test the fit of the pulley on the camshaft and insure that as you file the keyway you are able to rotate the pulley counterclockwi se on the camshaft a few degrees until the key in the camhaft W can slip freely into the area you just filed WITHOUT ROTATING THE CAMSHAFT.
when you have finished widening the keyway, fit it to the camshaft and again check that it is free to rotate counterclockwi se the full width of the keyway without rotating the camshaft.
temporarily install the camshaft retaining bolt, reinstall the timing belt, making sure that the three indexes,(cam pulley aligned with crease in cam cover, crank pulley aligned at tdc, distributor rotor aligned with tcd mark on distributor)
tension timing belt and rotate the engine by hand until slot in cam pulley backing wheel aligns with the crease in the cam cover.
Loosen and remove the cam pulley retaining bolt.
make a shim from steel rod stock, a nail or other item with the desired thickness. I used a 1 1/2" .075 diameter steel finishing nail which just happened to be the proper diameter. cut a piece about 1-1/8" long and bend one end at a 90 degree angle to create a tab to aid in inserting and removing the shim. (see detail in Figure 4). if the stock is too thick, simply flatten or file it to the desired thickness., I recommend .075"
Rotate the crankshaft COUNTER CLOCKWISE a few degrees so that the cam pulley rotates on the cam and the key in the cam rests on the RIGHT SIDE OF THE KEYWAY (toward 7 o'clock) leaving a space for the shim on the right side (toward 5 o'clock). as shown in Figure 4
Insert the shim on the 5 o'clock side of the cam key. Turn the crank COUNTER CLOCKWISE to position the shim against the keyway, and flip the bent tab on the shim up toward the retaining bolt hole, this will hold the shim in place and make removal / replacement easier in the future.
Install and tighten the cam pulley bolt..
You are done..
also.. since the thickness of the shim determines the offset and thus the cam timing, you can if you want experiment with shims of different thicknesses to vary the timing..
and if you ever want to return to factory timing, just repeat the install steps and insert the shim on the opposite, 7 o'clock side of the keyway.
THINNER SHIMS= LESS ADVANCE
THICKER SHIMS = MORE ADVANCE
be aware that small changes in the thickness of the shim prodices a lot of difference in the offset. From experimentatio n I have discovered that a .075 shim produces about 4.5 degrees, so i suppose you can assume that increasing or decreasing the thickness .015 would result in about a 1degree difference..
also, you probably wont notice a benefit at advence of more than 5 degrees and performance will degread at about 6 degrees.. about .090 shim.
Dont spin the tires too much