Real time timing question - first post

[sloanstavern]

Afternoon, and Merry Christmas

Very nice site you have here, I have just picked up an 85 K5 that my son and I are working one, and have a timing issue that has me scratching my head, and before I burn any more BTU’s thought I would float this for my first post. I did a search and could not find the solution.

It was running great when we bought it, but failed the first time through emissions, for CO. I rebuilt he carb, because it had some horrific leaks, and the test confirmed the rich condition. I also tried timing it and then is when the troubles arose. I now fly through CO but fail NOX and this may be due to poor / incorrect timing. Since that is the only knob I turned, I want to get it fixed before I try anything else.

I have a stock 85 with 5.7 and CA emissions my timing sticker is toast, but I found one on line and it calls for unplugging the 4 wire quick connect off the distributor then timing to 6 deg BTDC. Problem is there was no timing tab on the normal driver side about 2 o’clock. I hooked up the timing light and no matter how I twisted the distributor, I did not see the mark on the balancer at all.

Today I pulled #1 plug, brought it to TDC and the mark was visible on drivers side about 2’oclock right where I would expect it. I opened the distributor and the rotor was off ~ 40 degrees ( if it was 180 Off I would have known I was on exhaust, but 40 off???).

Put everything back together, then tried shining the timing light on the passenger side and saw the mark on the balancer, but no tab.

I am lost, do you guys have any idea what the heck might be going on?

Thanks

 

[dyeager535]

I'm going to have to assume the CCC system (what you are dealing with) is similar to TBI. Disconnecting the 4 wire connector sounds like the EST bypass used on the TBI rigs, so it makes sense.

Again, not knowing CCC specifically, I am going to assume that idle timing is advanced quite a bit (15+*, timing for TBI is 20+ at idle) with that quick connect connected. If it was connected I'm not sure you could rotate the distributor far enough to see the mark.

Is the timing tab really not there, or is it utterly buried? As I recall on these trucks it's pretty full of garbage in that area, making the timing tab hard to find.

Normally people have the rotor pointing at #1 @TDC, however it's not required. As long as the #1 plug wire is connected to the terminal on the cap where the rotor points at TDC, it will run fine. Not real likely, but it's possible someone did that. But if the #1 plug wire is on the terminal that roughly faces #1 cylinder, then something else is going on.

What knob did you turn? That statement confuses me a bit.

CCC is really a lost cause anymore (almost no one understands it, extremely limited), and unless really attached to it, if it gives you much more in the way of problems, you should rlook at converting the truck to TBI if you plan on keeping the thing. Steve Harrison was one of the guys online who used to mess with these CCC setups (Oldsmobile guy) but it looks like his page is gone.

I had intended to run CCC as that was what my vehicle originally had, but have decided to go with injection instead.

 

[sloanstavern]

Thanks , Does CCC = computer controled carb? then yes that is what I have. ECM and rocherster m4me I think.

The only knob I tuned means between emissions testing when nox went from no report to out of spec,, all I changed was the timing ( and the carb rebuild) so I am starting my trouble shooting there.

I looked and felt all around the balancer and found no tab. I bought one from O'riely and monted it in the traditional driver side ~ 02:00 location. I assumed that is where is should go is that correct?

I pull the 4 plug conector by the distributor, should there be a second conector by the master cylinder as well?
Thanks

 

[dyeager535]

Sorry if I confused you, like I said I'm not intimately familiar with CCC (you are right on acronym) moreso with TBI/TPI.

GM probably didn't set that up with the single EST bypass wire like TBI, thus the 4 wire disconnect. My only mention of that is because if CCC acts like TBI, you will probably lose ~20* of timing when you disconnect that plug. I just don't know how much advance GM was running at idle with the CCC setup. Might be able to google it, cars used the same setup from 1981-1990 if they were carbed.

Hopefully someone that has dealt more with the CCC setup can answer the timing tab location. For some reason I want to think that SOME Chev's had a timing tab that was used by looking straight down (12 o'clock) but I could be wrong on that.

I assume though, that if you could get a timing tab mounted, you can see good enough to know if there was another tab down there.

 

[sloanstavern]

Thanks
Good news, getting closer. I steped up the idle speed sufficnelty that it would not die, and I could turn the dist sufficnelty to get the timing mark to hold right on spec, then when I pluged the dist back in, and the mark jumped out of sight. Now for a test run.

 

[dyeager535]

Good luck with it! To mess with idle I *think* there is a bunch of stuff that is supposed to be done with dwell and all that (due to the MCS controlling idle mixture) but maybe someone monkeyed with yours in the first place, and you are just putting it back to where it needs to be.

 

[paratrooper307]

I never did get the timing on a CCC distributor the way I liked it. I decided just to start fresh with a basic distributor from Jegs and the crane adjustable timing kit, because I wanted to be able to limit the vacuum advance (A stock can will allow well over 20 degrees of vacuum advance, which is typically way too much when you start adjusting spring tensions)

Get a timing marker and one of those timing tapes that go around the balancer. The tapes are cheap and prevent you having to guess when the balancer mark starts to creep up past the water pump. They are also a whole lot easier to get a good reading on when you are trying to look through power steering pulleys and such while twisting a dizzy. I don't do emissions so I set mine at 14 degrees of advance at the crank, The mechanical advance in the distributor adds another 20 degrees, and I've got vacuum advance limited to 12 degrees because I don't run an EGR, and the engine seems happy with that.

I'm still running the CCC carb, which seems to be working fine with the new setup. At some point I will change it out for a conventional quad or an FI setup for simplicity and because I am suspicious of it lol.

The CCC carb setup is basically the answer to a question no one asked. It's not as good as FI, not as simple as a regular carb, and seems finicky and unfriendly to modifications. In my mind you're better off going with FI or just keeping it basic than trying to fool with it, unless due to local emissions rules you are prevented from changing it out. Hope yours works out for you!

 

[sloanstavern]

Getting closer. this morning, I pulled out the vacume gauge, and found and fixed several leaks.

Then set idle mix to more stable, higher vaume reading at spec RPM.
Fianlly tried the timing, but can not get it to stay and run at spec 6DBTDC. It will run at that level, but no power at all. Avanced to ~ 12-14TDC and it runs like a top.

I will take it in for emissions after Christmas and see what happens.
Clearly before I thow any more money at this I think I will otp for the new mechanical distributor.

Stay tuned

 

[496truck]

I had a Camaro with the CCC. IIRC the timing marks were at 12 o'clock. You had to shine the timing light straight down behind the water pump to see them.

One more thing to note, these harmonic balancers have been known to split at the rubber bond and this will allow the timing mark to move around as well as cause other issues.

 

[Blue85]

There have been a few locations for the timing tabs and more than one index of the balancer slot, so it's possible to get things mismatched when parts are replaced. If you know that the engine is at #1 TDC, then that tells you with certainty where your tab should be. Why would the rotor then be off by 40 degrees? Well the plug wires could all be off by one post on the dizzy. Or there is some kind of advance mechanism in there that is stuck. I don't know if there's anything different between a CCC and TBI distributor. It must be different from a carb dizzy if the ECM is really doing the timing, as the mechanical advance adjusts when the pickup coil signal is seen. And the ECM must get the pickup signal from the coil in the dizzy - I've never heard of a crank sensor or such back then.

It sounds like you are making good progress, by fixing vacuum leaks, etc. Maybe you can put an electronic DMM on the O2 sensor to verify the mix. To find out what the ECM is really doing with the advance you will probably need a dial timing light or you could put timing tape on the damper.

 

[rdn2blazer]

No input, just saying welcome to CK5. Sounds like you may have been lurking, and seeing what there is to offer here. It IS. THE. #1 Chevy off road site on the net. Period. You'll find a great group of guys here without the Pirate 4x4 attitude. There is a vasy amount of knowledge here, fabrication skill set is great here. Lots to learn. Good luck with your rig, and glad to hear it's a father & son build .