Carburation issue

[Dominic Salemi]

I just rebuilt my 1964 429 engine and I have a Elderbrock 1406 carburetor on it. I reviewed the blogs and I have an issue with it burning rich at idle. I talk with Elderbrock and they said advance the timing to 10 degree. My mechanic was hesitant but we did it. I still have a rich fuel burning also with black carbon out the exhaust. We are getting a little condensate out the back also. Any help or idea?

Thanks

Dominic

[David Thomas]

Timing, idle speed and mixture adjustments are made at no more than 480 RPM with the transmission in drive, A/C on if equiped. Look in your shop manual to find the step by step procedure for adjusting the carburetor and timing. Follow those steps to the letter to get your car properly tuned. As Jason and Tony said, be sure the ignition system is in good condition before trying to adjust the carburetor and timing. I agree with both of them, the timing should be set at the factory recomended 5° BTDC. The two idle mixture needles on the front exterior of the carburetor should be sufficient to get a proper idle mixture even if the primary metering jets, metering needles and step up piston springs are too rich or lean. Get it to idle properly, then play with the main primary circuit metering to get it to smoothly transition off the idle circuit and running down the road properly on the primary circuit. You'll probably need to buy the Edlebrock tuning kit that has an assortment of needles, jets and step up springs.You'll have fun learning how the carburetor functions, blending the idle circuit, primary circuit and secondary circuit, to smoothly run your car down the road.

[Jason Edge]

I hate to be blunt, but it sounds like the guy at Edebrock doesn't have a clue.  Anytime someone tells you to just advance the timing, I would be very suspicious. 

Sitting at idle, if you have a properly working distributor vacuum advance you are getting up to an additional 10.75 degrees advance on top of the engine 5 degree advance... assuming it is tuned to factory specs. Any time you start adjusting ignition advance by 5 degrees or so you are probably covering up a bigger problem, and will probably cause additional problems.

For example, if you set your engine to 10 degrees engine advance that means when the centrifugal advance kicks in at high RPM that can add up to 10 degrees of additional advance, you are forcing an additional 5 degrees of advance on the high rpm range is.

Regardless of your carb issues, I would not just move the timing out to 10 DBTDC so it will idle better.   Check each component. When I added my distributor and Pertronix ignition on my Caddy I guess 10 + years ago, it made me address a bigger issue, a worn out distributor, that threw the timing off a the high vacuum/low idle because of bad vacuum advance, but also on the low vacuum/WOT/high RPM end due to worn out centrifugal weight springs. I can say that investing in a rebuilt distributor to address both vacuum and centrifugal advance was the single best investment I every made, performance-wise, on my 64 CDV.

For more on understanding total engine, vacuum and centrifugal ignition advance I would check out this link: http://6364cadillac.ning.com/profiles/blogs/ignition-advance

Jason.