Base Timing Questions

Woodys_Cuda said

I ran across the same issue with timing my car (340,unknown agressive cam). I'm not a pro but I used the old school method of using a vacuum gauge for highest reading at manifold vacuum with the advance can disabled. Once I found highest vacuum (10hg) I backed the distributor back a touch. I put premium gas in it and watched for pinging under load and hard acceleration and backed off timing a touch. I then adjusted the vacuum can. I did not use a timing light at all, I gave the car what it wanted, the distributor already had a performance curve. Keep in mind that I started with a running engine that just needed timing and carb tuning.

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@340inabbody I just wanted to reply to the other part of your question regarding "idle quality". Once I did the above timing work I left the vacuum can disabled and made sure my center carb (sixpack) had only part of the transfer slot exposed and set the curb idle at 900 rpm. I then adjusted all six mixture screws for best idle while maintaining the 900rpm idle target. Even with this performance cam I can drop it down to about 550rpm and it won't die when I put it in gear, it's an automatic with a 3800 stall converter. Lastly I hooked up the vacuum can and adjusted it for best low speed performance without pinging or surging.

Again, I'm no expert but the above procedure worked well for me.