'81 CCC Performance and Timing

[Sensei]

Okay, so Big Bird challenged me a while back about performance with the CCC system. I have done a fair amount of performance mods to my car. While it is not a race car (that was not my goal) it is pretty satisfying when you floor it. I am using the hypertech thermomaster chip. I have used a computer to verify that the carb keeps the mixture at the ideal ratio for efficiency for normal driving and at the ideal ratio for performance at WOT. So the CCC system is in no way a liability to performance as far as air/fuel mixture is concerned.
I am not a timing expert and I know there is an art to setting performance timing. On my old truck, I just set base timing and call it good. For the car, the only way to adjust timing is with the computer chip (and a little bit of play with base timing). The stock base timing is 6BTDC. I set mine at 10. With the performance chip, I assume the timing curve is good, but as I said, I am no timing expert. Here are the numbers I have for my advance at various rpms. I'm not going to try and analyze these. As Fox News says "We report, you decide". It would be interesting to compare this to a stock chip. I might put mine back in some time and see what the difference is (don't hold your breath).

Base (computer disconnected): 10 BTDC
Idle (800 rpms): 31 BTDC
1500 rpms: 38 BTDC
2000 rpms: 43 BTDC
2500 rpms: 45 BTDC
3000 rpms: 46 BTDC

God bless, Sensei

 

[Peer81]

Very interesting topic, I'll follow it closely! Good luck

Groeten Peter

 

[GerryLP]

Chris,

One bit of knowledge I can share here is that when I asked Lars Grimsrud an opinion of what effect he thought would the setting of the initial timing above the specified 6 degreees he had this to say (the last line on his reply had to do about if he knew of anyone that could "burn" the chips on an L81):

"
Gerardo -
Yes, you can gain quite a bit by simply advancing the base timing on the CC cars. The ECM does not know the actual timing - it only assumes a set starting point and advances/retards from there. Since the entire curve is retarded from optimum for emissions purposes, you can gain performance across the spectrum by advancing the base timing to 12 or 14 degrees. However, your hydrocarbon emissions will increase significantly. Watch for detonation when you do this, and retard as needed to keep it away from the knocking zone. You'll also have to re-set minimum idle speed after altering the timing.

No, I don't know anyone doing the ECM chip burning for the early ECM cars - sorry.

Lars"

My Vette definitely likes the 14 degrees of initial timing I dialed-in. I was still able to attain the Air Valve Dwell close to 30 degrees (on the 6 cylinder scale.

 

[Sensei]

Gerry, If you are still looking, Jet performance was still burning custom chips last I heard, but at $400, I don't recommend it. God bless, Sensei

 

[big2bird]

Cris,
Thanks for posting the numbers. I'll check tomarrow on what I read as stock #s.

Now that I finally have my 700_R set to shift the way I want it, and the carb mess straightened out, I have been impressed with the performance.

 

[GerryLP]

Gerry, If you are still looking, Jet performance was still burning custom chips last I heard, but at $400, I don't recommend it. God bless, Sensei

That's just it, Chris!

I am able to remove the $400 off my wallet, but I can't seem to be able to let got of that wad of cash.Specially on something for which I have no idea what the return-on-investment will be.hnoes:ugh:L

 

[GerryLP]

Cris,
Thanks for posting the numbers. I'll check tomarrow on what I read as stock #s.

Now that I finally have my 700_R set to shift the way I want it, and the carb mess straightened out, I have been impressed with the performance.

So Big2bird,

Did you find the cause for that dreaded "miss"?

 

[big2bird]

So Big2bird,

Did you find the cause for that dreaded "miss"?

Yep. The guy who rebuilt it machined the throttle plates for a good seal, but failed to clearance the secondary jet wells. He also insatlled a screw, one of the three on the bottom, too long. It bottomed out before sealing the gasket. Although he did a fine job, a few details caused a vacuum leak.
Now that I have all the tools and gauges, I have it down. I find them easier than a regular Quadrajet. Less moving parts.

 

[big2bird]

Cris,
Thanks for posting the numbers. I'll check tomarrow on what I read as stock #s.

I'll check this as soon as I can pry my spousal unit out of the car. It runs so good, she don't come home now.:L