Installing the B&M Vacuum Modulator for GM TH350 & TH400 Automatic Transmissions, Part# 20234
The B&M Adjustable Vacuum Modulator (Part# 20234) comes pre-adjusted for ‘normal’ shift points, but it is fully adjustable (see below), allowing you to customize the shift points (within a range of 2-4 mph). This unit is designed for use with select applications, including GM TH400 and TH350 transmissions.
- Allows you to tailor shift points
- B&M Quality
- Comes pre-adjusted
- Fully adjustable
Please note: If you have a big camshaft and your engine does not make adequate vacuum, you will not be able to make the stock or B&M modulator work properly, usually resulting in late, hard shifts. A minimum of 12″ Hg engine vacuum is required for proper operation.
Installing the Vacuum Modulator
Adjusting Shift Points
You can adjust the modulator with a small screwdriver. Turn the adjustment screw clockwise to raise shift points and counter-clockwise to lower shift points.
Get the Kit
B&M Vacuum Modulator for GM TH350/TH400 Automatic Transmissions ~ Part # 20234 on Amazon
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