We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re having a closer look at problematic transmission.
D.S. Lakeworth, FL
Q: I have a Turbo 350 transmission connected to a 10-inch converter (3,300-3,500 stall). In the water box at the track, the car shifts fine. When I go down the track, first and second gear are OK, but as soon as I hit third at 6,000 rpm, the transmission goes in and out–no third gear. The transmission has been rebuilt by a specialist three times. The valve body has a shift kit and seems to work OK. I changed converters twice because the transmission guy told me it was bad.
For information purposes, the car is a 1973 Vega with a 355-cubic-inch/370-horsepower small block Chevy, Ford 9-inch rear-end with a spool and 4.56 gears. I have the transmission cooler mounted under the car, close to the transmission crossmember.
A: Judging by the symptoms you’ve described, we suggest you take another look at the valve body. It is possible that the spool may be popping out under pressure, or that the fluid is blowing by a check ball in the valve body itself. We’d suggest getting a manual valve body–it will be a lot more durable and give you more consistent performance.