CrossfireTechSeriesIndex.htm

TIPS FOR INSTALLING A DISTRIBUTOR AND SETTING INITIAL TIMING

Installing a distributor is arguably one of the most frustrating things a novice mechanic tackles. And setting initial timing can seem like something that requires prayers or perhaps black magic.

This is not meant as a comprehensive HOW-TO article, just some tips on setting the initial timing when installing an HEI distributor.

TIP:

1) Bump the engine around till the timing tab shows between zero and 6 degrees advanced before you pull anything apart.

2) Get a silver paint marker (or some type of tabs) and number the plug wire ends at the distributor cap. At TDC, the rotor is pointing to either #1 or #6. These are on opposite sides of the engine so it should be easy enough to determine which it is. From there number around the cap thus: 1-8-4-3-6-5-7-2.

3) After you get the cap off, put alignment marks on the dizzy housing and something nearby (like the manifold lid on a crossfire) and also mark the position of the rotor.

4) Two words . . digital camera . . . 'nuf said.

In this case, you can put the dizzy back in with the rotor pointing the same direction as when you removed it. Note that it will often want to go back in one tooth off from where you took it out. Your mission is to dissuade that behavior and get the dizzy back in on the same tooth you took it out on . . i.e. with the rotor pointing in the same direction.

TIP: the dizzy drive gear is helical cut so the dizzy rotates as you lift it and as you set it back in. The oil pump is also driven by the dizzy drive gear via a slot in the pump shaft that fits onto a pin (or tang) in the bottom of the drive gear. The dizzy will not seat down all the way if the oil pump drive shaft does not mesh up with the dizzy drive gear. If this happens, you will need a large and long flat bladed screwdriver or equivalently shaped tool to poke down into the dizzy hole and rotate the oil pump shaft into position.

It may take some fumbling around and a few tries and some 'plumber language' to get it done, but persevere, it is doable. The trick is to remember that the dizzy shaft is turning as it goes down so you need to set the oil pump shaft a little off from where it seems it should be so that it will mesh up after the drive gear has rotated down into position.

There is a little play in the dizzy so when you get the oil pump shaft positioned ‘perfectly’ and you lower the dizzy in and it still won't seat, you can wiggle the rotor back and forth while you gently repeatedly bump the dizzy on the oil pump drive shaft. If the shaft was pretty close to the right position, sometimes this will nudge it into alignment and the dizzy will plunk right on down.

If you did NOT set the engine at TDC before you pulled it apart, then you will have more hair left at the end of the job if you put the dizzy back in first and then mess with the timing. This way you can use the rotor position that you marked before you took it out. Follow the procedure above to get the dizzy installed in exactly the same position it was in when you removed it.

THEN, bump the engine around to TDC and get timing between zero and 6 on the timing tab.

SETTING INITIAL TIMING:

TIP: HEI uses a reluctor (I think that's the right word) to trigger the spark. If you remove the rotor, you will see the sharp spikes on the reluctor and the outer ring. The plug fires when the points are closest to each other, so rotate the dizzy until the points are lined up and that will be the firing point for whatever plug the rotor is pointing to. Make sure that the rotor is pointing at either #1 or #6

Tighten the dizzy bolt just enough that you can turn the dizzy with some effort and have the timing light ready when you fire the engine. Disconnect the advance wire (brown or tan single with a separate single connector near the dizzy). fire the motor and set your advance. Reconnect the advance wire. Observing with the timing light, you should see the timing jump up and also react to revving the engine when the advance wire is connected.

If you are putting in a new motor or if your engine got cranked somehow while the dizzy was out then you start from scratch. Not a big deal, just get the motor to TDC as before, but remember that there are two TDC positions for every cylinder.

Bump the engine around to TDC and make these observations at the number one cylinder (front left) while the crank is turning;

1) air rushes out of the plug hole as the cylinder approaches TDC on the firing stroke. (sticking you finger in the hole while the engine is cranking is NOT a good idea)

2) the valves are closed at TDC on the firing stroke and are not fully closed on the exhaust/intake TDC.

Note #1 exhaust/ intake TDC is also #6 firing TDC. So if you find you are at #1 exhaust/intake TDC, you can either bump the motor around again, or simply set up using #6 plug wire instead of #1.

Once you have the engine at TDC (or actually anywhere between zero and 6 degrees advanced) and you have determined which TDC it is, you can begin the initial timing setup.

TWO pre-requisites to address before you get to far and have to re-do a bunch of stuff:

1) Some cars, including crossfire, need to have the dizzy housing within a certain positional range in order for the wiring harness to reach it and for it to clear various obstacles.

2) pre-cut ignition wire sets often will only fit with the dizzy cap in a certain position. In my experience, this is an issue with the shortest wires in the set no being able to reach the far side of the cap.

TIP: If your manual provides no direction and you are not certain about the position of the dizzy, plop the dizzy in place with the cap on. Don't worry about trying to get it seated for now, just check that you can get the wiring harness connected and note where the #7 an #8 (rear cylinders) positions on the cap are. A good default position is with #1 pointing toward the front of the car, but you will need to noodle over your own setup. This is time well spent, because if you get everything together and then that last plug wire won't reach . . you get to pull it all apart and start over.

Once you figure out where the dizzy housing needs to be and where #1 plug wire goes in the cap, you can follow the above procedures with the target being the rotor pointing at #1 and the reluctor spikes lined up.

Good luck!

- Steve Simpson

If anyone finds errors in this tip sheet or has some more tips they would like to see added, feel free to contact me at steve@thecubestudio.com