Joined: 04 Jun 2006
Location: Gaithersburg MD
Installing and timing the lean burn distributor.
(Mon Sep 05, 2011 4:44 am)
|The first thing we did down at Peter's place was get the new locked distributor installed and timed. It was very simple, and basic. If you follow these simple steps you will have your distributor in and timed correctly in short order. This process assumes a currently running car. And it assumes Mega Squirt II.
1. Rotate your engine by hand with a wrench on a crank bolt until the timing mark lines up with the 10 degrees advanced tab. Paint a stripe on the crank right at the TDC mark on the tab. Then rotate this mark to the 5 degree mark and paint a second mark. You will likely have to clean the muck off and sand the balancer for the paint to stick. You now have marks that are TDC, 10 advance and 15 advanced on the wheel. By using all mark on the pointer you can determine any setting from TDC to 25 degrees advanced.
2. Mark the top of the distributor body so you can see where number one spark plug tower is with the cap removed. Do this on both the new and old distributor.
3. Label your spark plug wires with the cylinder numbers 1-6 in the proper order, and remove the cap with the wires installed, and remover the wires from the plugs. Set this all aside.
4. Rotate the engine by hand, with a wrench on a crank bolt until the rotor lines up with the number one mark, and the 15 degree mark on the crank line up with the 10 advanced mark on the pointer. This is 25 degrees before TDC.
5. Pull the old distributor and and install the new one so the rotor points at the mark you placed on the body of the distributor for number one. INstall the lock plate, and tighten it enough so that if needed you can twist it a bit if you need to later.
6. Rotate the crank by hand until the VR pick up vane is pointing directly at the magnet tip. This is made easier with an assistant. AT this point, the 15 degree mark should be on TDC. Let me review here: The rotor tip should be aligned at 25 degrees BTDC and the pick up vane should align at 15 BTDC. Don't ask me why this work. It just does. Someone smarter the me needs to answer that question.
7. Install the cap and put your spark plug wires back on their proper plugs.
8. Start up the engine and check the timing with the timing light. You need to lock the computer timing to do this, as otherwise it will try to set timing from the computer and give you a false reading. The HEI harness has by pass wire that can be unplugged to disable the timing control, and that is what we did, however there is a function in MS to do this.
9. Set the base timing at 10 degrees and lock it down. Mine ended up actually at 12.5 degrees BTDC. Peter elected to just leave it at that, and set the table in the timing section to indicate that the base timing is set at 12.5. The computer then adjusts all timing settings from this basic timing.
The Mopar lean burn distributor is perfect for MS's requirements. If you do not have access to one, you must lock the inertial part of an advance distributor, and set the pick up plate so that the VR vane passes the pick up magnet at 7 degrees after the rotor is at number one plug tower. You must also lock it in this position. This translates to 15 degrees at the crank.
I wrote this up because this has always been a point of mystery for me in the past. Interfacing a dizzy with EFI had a certain black magic quality to it. The key to getting this done correctly.
1. Mark the flywheel correctly.
2. Mark the BODY of the distributor for number one.
3. Establish compression stroke before removing or turning the old distributor.
4. Label your spark plug wires and get that thing out of the way.
It is easier to turn the crank with a large center crank bolt installed. The factory does not supply this, but you can add it, and I did years ago when I rebuilt the engine.
I hope this helps. As you know, I am no genius and have much to learn, but am eager and willing to share what I pick up in this process.
A REAL professional is someone who knows when to hit it with a bigger hammer.
Last edited by Sam Powell on Mon Sep 05, 2011 5:47 am; edited 2 times in total