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Marc By the time you get to more than about 1/3
throttle no amount of vacuum leakage will affect the mixture to the point which
would cause a ping. What is the base timing set at? Is the mechanical advance working
correctly or is it advancing way too far. You say you went up two sizes on the
metering springs, did you also change the metering rods. At heavy loads the
size affects the mixture, the springs only control what vacuum is required to
pull them down to the lean step. I assume you are running an AFB. You can email
me off list if you wish to discuss this further. Ernie and The Black Bitc_!! -----Original Message----- I am
finally able to drive my car farther than the video store, and now I have a
problem thats kickin my butt. A couple of years ago I put pertronix ignition on
my car. It has never went very far, because of my brakes until recently. I
notice now I have a pinging. It used to be very bad, and I regapped the plugs
an extra .005 of an inch and it cut the noise in half. I have retarded the
timing another 5 degrees and That also helped alot. But I still have ping. I
went up 2 sizes in metering rod springs. no change. It seems to do it when its
warmed up a lot. I disconnected and plugged the line into the brake booster to
see if that was the culprit. I had my tach and timing light on it,
watching intently, and then I noticed something strange. the car had been
running now for about 5 minutes, after a couple more minutes, I saw the RPMs
start to go up slightly, about 100-150 RPMs. STRANGE! I sprayed a little
starter fluid over the carb, and it acted like it wanted to die. Not exactly
what I was expecting, but I know how the car will act if it gets ether spay
sucked in. I started spraying around the intake manifold and the base of the
carb. I have it pin pointed to 2 spots where the car wants to die when I spray
the ether. One on the base of the carb and the other on intake manifold.
Will a vacuum leak like this cause my car to ping as it gets warm, especially
hard throttle and going up hills???? I really need some good insight on this. Just to
answer the obvious questions first- I am using 91 octane with 104 Octane
booster, The engine was rebuilt about 3 1/2 years ago, the vacuum advance seems
to work, and I am using Autolite 75 plugs. (the only difference according to
parts man between these and 85 is that one is resistance and one is not, I
guess it affects radios and computers). Any help or answer to my questions are
greatly appreciated. Marc
1960 4drht. |
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