Join Date: Mar 2002
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Re: CJ Carbon build-up on S/S valves
Fran, is the buildup on all the valves or possibly just the ones where you had the intake gasket leak? I wouldn't think that a leak generating a lean condition could cause that, but I don't know for certain.
On a brand new head ('specially a high$ one from Clifford) you should not be having that kind of buildup. It might not be the head though... could be caused by your fuel mix and timing not being set right.
Have you hooked up a digital voltmeter to your O2 sensor? That was how I wound up tweaking and tuning mine. It was a lot more convenient that checking plugs because I could run the leads inside the Jeep and watch it while going down the road. .5 volts is "perfect mix". Toward 0 is lean. Toward 1 volt is rich.
From some previous posts, it seems like I remember you were getting pretty sad mileage... something like 11-12? Sounds to me like you just have a fair amount of tuning to do. I know I did, and it really surprised me the difference in performance and mileage I got out of it. I am now getting 19mpg and have awesome power delivery everywhere vs. 15mpg with detonation and holes in the power when I started.
I also wound up changing out one of the mechanical advance springs in my distributor to slow down the advance. This helped eliminate my detonation. I would suggest getting out there with a DVM and play with your jet sizes, idle mixture screws, and timing. You might be surprised at the difference it makes.
Let me know if you want more details about what I did to mine.