Chapter 9 of 13
Tappet Plate Timing
Tappet fin geometry for a single-sector brushless build, the calipered cut spec, and the short-stroke pairing required for any selector that includes auto or burst.
7 min
- Step 1
Overview
For a brushed build or a brushless SSG you do not normally need to change tappet timing — unless you short-stroke a meaningful number of teeth. Tappet timing is the single biggest factor in a brushless DSG, which is why getting it correct on the SSG is treated as a rehearsal for the DSG procedure.
- Step 2
Supplies
- Hammer
- 80 and 120 grit sandpaper
- Fresh razor blade
- Tappet plate (TRDA is our reference)
- Digital calipers
- Step 3
Procedure
- Measure 12mm along the tappet fin length with the calipers. Mark the cut line.
- Cut to 12mm with the razor blade in clean strokes. Do not rock the blade.
- Trim the front of the tappet fin so the front-to-tip dimension is 11.5mm. Razor again, then knock the edges with 120 grit so the cut faces are not raised.
Reference video: https://youtube.com/shorts/MPKqVNxQOt8?si=Piu1VQSjtlr1AE4g
- Step 4
Short-stroke rule
Mandatory: if the build will ever fire burst or full auto, you must short-stroke at least two teeth. Our default is SS 2 teeth on the pickup side of the sector. For any short-stroke beyond two, we shift to 2:1 (pickup : release) — two on the pickup, one on the release. Anything more aggressive than that requires re-validating the tappet cut.
A semi-only SSG can ignore the short-stroke rule, but the moment full-auto is enabled on a stock-length tappet with a clipped sector, feed timing breaks and the nozzle clips the next BB.