Solenoid-controlled quick spool valve for the GM Turbo 400 that helps a turbo engine build boost at the line on a brake launch. Replaces PCE676.1005.
Turbo TH400 cars have a familiar problem at the line: the converter is tight enough to drive well everywhere else, but on the footbrake or transbrake the engine will not rev high enough to light the turbo, so the car leaves with no boost and spools halfway to the eighth-mile. A quick spool valve system attacks that problem from the transmission side. This one bolts onto a GM Turbo 400 build, replaces part number PCE676.1005, and is switched on only while you are staged.
In the TH400 the pump charges the torque converter through the pressure regulator, and the oil leaving the converter goes to the cooler and then back in as lube. A converter that is fully charged couples tightly and holds the engine down against the brake. Converter dump and quick spool systems work by letting part of that charge volume and pressure bypass the converter while a solenoid is open. ATI describes the effect on its own dump kits plainly: the converter loosens, a turbo engine spools more readily, and the car can make a more controlled launch with less initial wheel speed. When the solenoid closes, the converter refills and the car drives normally.
The kit itself is a painted, machined aluminum valve with a high-flow electric solenoid, a mounting bracket, a stainless braided hose with a tee fitting, and three threaded adapter fittings for plumbing it into the transmission. It weighs about 2.4 lb.
Rule out a transmission problem first. A TH400 that slips on the brake, engages late or loses line pressure will feel like a loose converter and will not be fixed by a dump valve. Our TH400 delayed engagement guide covers pressure checks, and the TH400 valve body testing guide explains how a sticking regulator or boost valve changes converter feed. If the unit is healthy and the problem is only staging rpm, this is the right tool.
This system is made for the GM Turbo 400 (TH400 / 3L80) three-speed automatic only, the unit used from 1964-1990 and in countless race builds. It does not fit the Powerglide, 4L80E or other GM automatics. It works with stock and aftermarket TH400 cases, but check that your case and cooler plumbing leave room for the bracket and hose before ordering. Send us your case type and transbrake setup if you are unsure. More race and street parts are on our TH400 parts page.
Most cars that need a quick spool also run a transbrake; the billet TH400 transbrake valve body pairs with it, and a turbo launch is hard on the low roller, so the TH400 low roller clutch upgrade is worth a look.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is built for the GM Turbo 400 (TH400 / 3L80) three-speed automatic and replaces PCE676.1005. It does not fit the Powerglide, 4L80E or other transmissions. Make sure your case and existing plumbing leave room for the bracket and hose.
Wire a fused, switched 12V feed through a push button, a delay box or timer, or a digital output from an ECU or launch controller. Most setups tie it into the brake or transbrake circuit so the valve is only active while the car is being held on the line.
Not when it is switched off. With the solenoid closed the converter is fully charged and the transmission operates normally. If the converter feels loose with the switch off, check the wiring and the solenoid for sticking.
Keep it to staging. In the TH400 the oil leaving the converter also feeds the cooler and lube circuit, so long dump times reduce cooling and lubrication.
The machined aluminum valve with a high-flow solenoid, a mounting bracket, a stainless braided hose with a tee fitting, and three threaded adapter fittings. Wiring, switch and fuse are supplied by you.
