I have kind of walked away from my Cobra since around June.? Partially because I was busy with other things and partially because I was getting frustrated with it.??
Things started when I had the brake booster rebuilt due to a vacuum leak.? It had been leaking for a long time and the engine was tuned with that leak so when the vacuum leak was fixed, I could not get it to run quite right.???While diagnosing the problem, I discovered the vacuum advance diaphragm had a vacuum leak too and installed a new one.? This made the engine tuning worse.? I thought it was the carburetor did a thorough cleaning and checked everything out.? The engine still did not run right.??
This past weekend I hooked up a vacuum gauge, timing light and an accurate tach.? I started recording everything at different rpms and came to the conclusion the vacuum advance was advancing the timing too much.? It is an adjustable diaphragm and I had adjusted it according to the manufacturer's instruction for my engine. The adjustment is with an Allen wrench through the vacuum port.? I adjusted it about 2 turns clockwise.? This advanced the timing at idle but reduced the timing at 2000 rpm.? I knew I was going in the right direction.??
After resetting initial timing, I took the car out for a drive, and it was running much better.? The only thing I did not like was as soon as I stepped on the accelerator pedal it surged forward.? I like to take out easy, so it doesn't look like I am trying to race everybody.? I am sure I can adjust this with better tuning.? Back in June, I had also adjusted the accelerator pump to dump more fuel initially from an idle to try to eliminate a hesitation.? I think I will set the accelerator pump back to what was and then work more with timing again.
I have found that the 428 CJ doesn't run the best when using Ford specs for tuning.? I have heard this from many sources and experience.? Right now, the initial timing with no vacuum advance is 11 degrees at 700 rpm.? Full advance is around 40 degrees with vacuum advance.? I can probably set the full advance a little higher, but it is pulling very strong at WOT already.?
