I'm trying to set the timing on this engine, and I've searched everywhere about disabling the spark advance on the HEI ignition systems. For what I have, I believe it's a matter of unplugging the 3 wire connector that comes out of the base of the dizzy and connects next to the BAT/TACH connections? Can someone tell me if this is correct?

 

No , you don't unplug anything near the distributor or coil . You are looking for a single wire connector that will be somewhere near the blower for your heat/ac under the hood on the passenger's side near the firewall . I can't recall the color of the single wire but the connector is a black rubber molded piece that when unplugged has a male and female side .

 

I don't see anything like that, anywhere on that side or near/on the firewall. The closest thing I found was a single red wire with a plastic male connector that connects to a dual socket connect that has a red and black wire. The black wire goes to the hood light. I seriously doubt this has anything to do with what I need, but again, it's the closest thing to a single wire connection that you spoke of.

(BTW, I corrected my 1st post. I was thinking 4 wire, but it's actually 3 wires that connect next to the BAT/TACH connections on the dizzy cap.)

I've read about the single wire as you talk about, but I've also read about the 3 wire connector (ESC?) needing to be disconnected, too. I guess it depends on the type of engine which one is used. (Forgive me, but I'm not familiar with HEI ignition and have never set the timing on a third gen engine.)

This is a carbed (Rochester Quadrajet) 305 HO in a 1984 Camaro Z28 with the HEI ignition.

 

Wait a minute. Does the HEI distributor have the vacuum advance on it like the old style distributors? If so, mine isn't like that. Maybe it's not HEI at all. I've been searching left and right trying to find out information, and for the life of me, I can't find anything.

 

Try looking right behind the passenger side valve cover; right around the dipstick; it's probably hiding out there.

 

Yep , Like Bob says it could be near the transmission dipstick . I have never heard of a different method of base timing our cars other than the disconnection of the single wire . I know it may be tucked away real good , but it should be there . And yes , your correct in that your distributor should NOT have a vacuum advance , our engine's advance being controlled by the EST system . This is why you cannot set the timing without putting it into "base timing mode" by unplugging that wire . If the EST is functional while your trying to time it , every time you move the distributor the EST will move the timing back to where it thinks it ought to be , rather than the base setting you need . You will set a trouble code when you run it with the EST bypassed , and will need to clear the code when you finish setting the timing and reconnect the EST bypass ....

 

PS , this carb does have the ECM controlled mixture control solenoid in place and functional , I hope ? If someone has put a "non electronic" carb on it the ECM will always be in open loop and I don't think you get optimum timing curves that way .....

 

Yes, this carb does have the ECM controlled mixture solenoid in place and functional. It's the CC Rochester E4ME.

I think I've located that connector, but I'll have to verify it, later. I'm in the middle of buttoning up a few other things. (I was trying to find out where this connector was before I actually checked the timing.) It looks like it's stuffed down behind the distributor in-between the firewall and the back of the intake and xmission bell-housing. I'll need to remove the dizzy cap to fish those cables out to be sure that's where it's hiding. I'll report back once I find something.

 

on the CCC carb engines,electronic advance is disabled by disconnecting the 4-wire plug from the base of the distributor to the ECM harness-if 3-wire plug from base to cap is removed,engine will not run.On injected engines,EST bypass plug is disconnected as mentioned upthread.

 

THANK YOU! I know where that plug is. I had to disconnect it once before when I had to remove the distributor.

Everything I read said it was a four-wire connector, but I wasn't thinking of the one that you mentioned. All I saw today was the three-wire connector at the base of the dizzy that connects to the dizzy cap, and I forgot all about the four-wire connector.

I do appreciate the help.

 

Thank You !


And my sincere apology to the OP , I have only seen the injected setup and had no idea the CCC carb did it different .

 

No problem.

I've read several threads that talked about the connector you referenced, and I figured it had to do with fuel injected engines. But now, we both know.

 

^^^ This ^^^

The plug is a wide flat Weatherpak, usually ends up kinda laying behind the engine sorta on top of the bell housing flange. You can feel around the base of the dist to find it. Alternatively, if the dist is in the factory orientation, with the 3-wire plug to the cap facing directly toward the driver's side, the harness comes out of the base almost straight rearward, at the same "level" (specifically, where the cap meets the casting) as where the 3-wire one comes out the front.