When test driving it, try not to hit it from dead stop, keep it rolling and ease into it, you eliminate most of the accelerator pump issues this way. Once you get the full throttle and cruise A/F ratios in the right range, then you can go to work on the pumps and nozzles. Jetting has some effect on off idle, but the pumps, ramps, and nozzle sizes are the main tuning points. Get the timing set, then the jetting, then the pumps. Modern fuels don't color the plugs like the old fuel did, so once they clean up, its pretty hard to read them. Start with finding true TDC and make sure the pointer is correct. Also be sure you have the correct voltage at all times to ignition. Full throttle A/F should be in the 12.5 to 13.5 range, and cruise A/F should be 14.5 to 16 in ideal conditions. Be sure to run it hard when testing full throttle A/F ratios, the engine needs to be hot, 2nd and 3rd gear full pulls to give it time to stabilize, just don't get caught !
Shown 50 You have posted a lot of the info to help diagnose your problem. I agree with everything suggested. 2 items need to be checked. Float levels Fuel pressure I'm available for phone tech support. Faster response than messaging.. 831-262-7294. Call anytime. Dave
One thing about an AFR gauge, it can be confusing in that if there is an ignition defect, it will indicate a false lean condition. You mention in the first post some popping in the exhaust at times, see fouled plugs, and also some momentary lean numbers on the AFR gauge. The O2 sensors are just that - they measure O2, not fuel. SO, if there are plugs misfiring, there will of course be unburned fuel, a rich fouling condition - but the O2 sensor don't know that. It just knows that there is also unburned O2 - (remember it's misfiring in this scenario) so it will indicate a "false lean" condition. What happens when plugs misfire and the exhaust starts loading up with unburned fuel? Now a true lean condition can also cause popping in the exhaust, sure. But given the story here of excessive plug fouling and popping through the exhaust ... Could be wrong, just thinking out loud here. But the folks selling the AFR kits will be the first to tell you it is important that the ignition is straight. The ignition timing curve (and everything else like fuel pressure, float height/fuel height etc) must be squared away before trying to tweak the fuel curve. You'll get it, just keep at it and keep making a new pass through on all the baseline adjustments and sneak up on it. Modern gasoline doesn't burn like the old gasoline, if the plugs are black, then it is way, way off on the rich side. It goes against what we saw or heard growing up. The "base ring" is what shows jetting. If it shows black carbon, it's too rich at cruise. A too fat idle will also tend to load up the plugs after a few minutes and cause fouling. Make sure the power valve is not defective before trying to set cruise jet. Want to be about 2 jet sizes richer than "lean surge" on steady level ground for reasonable economy. This will affect the wide open throttle AFR, so jetting is done first, then make sure you're plenty fat on wide open throttle. Use "stock" heat range spark plugs for baseline tuning. There is a tendency for people to install hotter plugs when plug fouling occurs. The idea is to optimize the fuel curve first. If anything you might even need a cooler plug once you get the ignition timing and jetting straightened out. But the plugs will tell you what's really going on, you'll need a magnifier and a strong light.
Sorry for the delay been down with back issues and shotty previous brake work. I just wanted to update this for anyone else dealing with similar issues. Dave from the Hamb has been the only reason that this is fixed, he has helped me in more ways than I can explain on here. Multiple shops and mechanics have tried to help to no avail Dave walked me through how a carb works and has taught me how to make adjustments and changes that have solved my issue. The main problem I was experiencing was being the car ran rich no matter what change I made to jetting, choke, transition slot, etc.. Dave walked me through returning the carb to stock all around then we removed the choke which was not adjusted correctly and is not needed for my application, set the transition slot, and finally checking the fuel pressure. The fuel pressure was the main issue that he found to be causing my rich condition. The pressure was at 7.5-8 psi from the mechanical fuel pump so I installed a knock off holley regulator from jegs which solved the issue for 1 mile then the regulator diaphragm failed. That knock off was replaced with a Holley which after adjusting to 5-5.5 has resolved all my issues. We are still going to check valve adjustment and timing just for peace of mind. The sole reason for the update is to hopefully save another carb newbie from months of frustration and the savings of swapping to fuel injection along with thanking Dave for all the help. Without him my car would still be fouling plugs, sounding like a machine gun through the exhaust, and pouring raw fuel and black smoke from the exhaust like a diesel. Thank you Dave and thanks to the Hamb for having an outlet for people like me (without experience or someone to teach us) to go and get answers and help from members
Here are some more ideas for future readers of this post is case they have issues beyond yours MSD recommends NOT using a dial back timing light. I always mill file the main body on holleys, doing this has cured a lot of mysterious tuning issues, takes about 20 minutes per end using a hand file, has made a world of difference. I've done this to about a dozen holleys and they were all concaved, new and used. Also verify you have no more than 7 psi to the carb, needle and seats are clean of debris, floats set using a 7/16" drill bit between the roof of the bowl and the top of the float, (flip the bowl upside down to adjust), and last but not least a blown power valve will cause your troubles too, use an 8.5 power valve. Take the vacuum reading at idle and divide by 2 to arrive at the proper power valve needed.
The Jalopy Journal
