1972 Carb./Ignition problem ?

[Sebastian Aruta]

Sorry for this long one - but want to give all details that i can...

I bought my first stingray (auto) two years ago. It was a survivor in fairly good original shape, needing only an ignition tune-up and it's been a good weekend driver since. However, i've had a nagging power problem since the beginning. From a dead start, if I give too much throttle, i get back-firing and big hickups through the carb. Once Im above 20MPH the car runs great and strong. I was able to clear out the back-firing when parked and idle using the carb's fuel/air mixture screws, but when at load, it does the same. On someone's suggestion that it could be an ignition problem, i changed all plugs and wires again - but still no fix. Some say it is the Rochester Quadrajet's accel. pump, but i see it spraying gas fine parked and off? I tried bypassing the TCS switch solonoid between the carb and the distributor vacuum advance input, but that made no real difference. Funny thing is that one night of fooling around with the carb and timing the car tore off the start like a dream all night. Thought it was fixed until it did the same thing all over again next day and since. Before I pay to have someone rebuild the carb. and find out it didn't fix the problem, does anyone have any suggestions of where I should look next? Keep in mind that I changed all of the above,including dist. cap, rotor, points, condensor already.

Thanks,
/Sebastian.

[Michael W.]

Re: 1972 Carb./Ignition problem ?

There's lots of things that can cause the problem you describe, including internal engine wear (camshaft lobes), but have you verified that the air valve for the secondaries is balanced properly? Qaudrajets are famous for 'bogging' if the valve is allowed to open too easily.

Mike

[Sebastian Aruta]

Re: 1972 Carb./Ignition problem ?

Mike,

You just made my year. It was just what you suggested. To be honest, I didn't know much about how that valve worked, but it was simply flapping and staying open. The allan screw that holds the spring adjustment screw in place was not tightened down. Once I adjusted so that there was enough spring tension to flap back everytime - the car stopped bogging down at take off.

It's not perfect (some more adjustment for sure) but I am smiling all the way to bed tonight!

Thanks again!
/Sebastian.

[Michael W.]

Glad it worked! *NM*