I have searched for this answer but having quite seen the info I'm looking for. I am trying to set initial timing on a 350 with a roots blower that is using the ECM from the original 305 H.O. L69 engine. Every manual I have explains how to set initial timing on a non QJet engine. I don't have the easy connector fuel injection wiring harnesses have to disconnect the computer timing so should I set initial timing with the 4 wire distrib connector unplugged? What should the initial timing be (I have to pass emmissions)? I think factory initial timing was either 0 or 4 for this engine. After I plug the computer back in what should I see timing wise approximately at idle? I know this seems trivial but it is making me nuts.

Thanks,

Glen

 

Turn the engine off. Disconnect the large 4-wire Weatherpak coming out of the base of the distributor. Start the engine. Set timing. (SES light will come on) Turn engine off. Reconnect plug.

Correct timing setting is 6° BTDC IIRC, with the wire disconnected. It will tell you on the sticker on top of the radiator.

It will go to somewhere around 20° when you hook the plug back up and check it again.

 

Many thanks. That gives me some piece of mind and a place to start. The stock radiator and its sticker were gone years ago I'm afraid so I can't reference that.

Glen

 

Update: I reset the initial timing to 6 degrees with the computer unplugged and then hooked everything up and fired it up. You nailed it. At idle it is right at 20-22 degrees. Awesome. Now if I can just figure out how to tune this thing.

Thanks for the help.

Glen

 

Sounds like an awesome project!! I have a rebuilt L69 sittin on a stand for over a year....did you change to lower compression pistons for the extra boost? Oh - I also have the CCC Q-jet and complete ECM harness,sensors too!!

 

Well when I bought the car I bought it for the body for cheap. The L69 had been very abused and thrown a rod. I took it apart just to see the damage knowing it was all junk. I started the buildup with a new 4 bolt main block. All my choices were made knowing I was going to get a roots type blower and that I had to pass emmisions. Compression is right at 8:1. AFR 190 heads,COMP cams, roller rockers, blower with manifold for emmisions, rebuilt CCC. I upgraded the ECM, PROM, and spark module with the ones from the ZZ3/4 package. I kept the EGR and the A.I.R. system with cat. 2 kids and a stay at home wife have really shot the car budget so it is slow going now. I sure have learned an aweful lot though.

Later,

Glen