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Shift RescheduledI have owned an '84 Camaro Z28 for a few months. The car ran well when I got it, but I thought it might pick up some power if I swapped the intake. I installed an Edelbrock Performer RPM and then reinstalled the factory computer-controlled Q-Jet. The car started right up and is running well, but now the transmission won't shift properly. I'm afraid that maybe I've confused the computer somehow, possibly by altering the vacuum signal or something like that. Is there any way I can get the computer to make the trans shift right? Do I have to have it reprogrammed or get a new chip?Adam HelmsenReno, NV
You may suspect that the computer is the culprit here, but you're giving the ECU on your '84 Camaro way too much credit. Back then, the ECU was much less involved with the rest of the car than modern automotive engine management is on typical late-model cars rolling off assembly lines today. The ECU on your car can alter air/fuel mixtures through the carburetor and ignition timing through the distributor, but the only control it has over the transmission is in the lockup function of the torque converter-shifting still occurs via mechanical means on that TH700-R4.
The problem is most likely in the adjustment of the throttle-valve (TV) cable, which links the carburetor linkage to the transmission. Many people overlook the TH700's TV cable as a source of problems because they think it's simply a down-shift linkage, as found on the super-common TH350 transmission. However, the TV cable plays a more vital role in the operation of the TH700. In a sense, it acts as a throttle-position sensor for the transmission, indicating how far open the throttle is at all times. When the cable isn't adjusted properly, shifting doesn't occur at the right times. The potential danger to the trans lies with the fact that the TV cable mechanically raises the transmission's internal fluid line pressure as the throttle opens, so if the cable isn't being pulled out far enough to raise line pressure by the appropriate amount, damage can soon follow.
When you installed the new intake, the relationship between the TV-cable bracket and the carb may have been altered-it only takes a slight movement to cause a significant difference in shifting. To readjust the cable, look for the large plastic housing surrounding the cable on the backside of the cable bracket. There should be a "button" to depress, which will unlock the cable sheath and allow adjustment. Most mechanics advise to push the button and depress the accelerator to the floor, but with older cables this can often pull the sheath too far forward. A more accurate approach would be to adjust one "click" at a time. If your car feels like it's shifting too soon, pull the sheath back towards the firewall. If shifting seems delayed, allow the sheath to more forward toward the carb a notch. It's probably a good idea to mark the sheath before unlocking it, as they will often move as soon as the button is pressed. Also, you should expect the button to be a little stubborn at first if it hasn't been touched for some time. A little spray lube may help, but don't get too rough-it's only plastic.
Goat UpdatesI want to turn my '67 GTO into a street machine using '90s technology, but I'd like to use a low-buck approach. Would it be possible to use a late-'80s F-body TPI engine and overdrive transmission without too many modifications, or should I just go with an overdrive trans swap?Brianvia e-mail