Disappointing dyno results

jawbone said

cyl vol = bore squared x stroke = 4.070 x 4.070 x 12.87 = 213.19026
213.19026 x 3.313 = 706.2993 cc

gasket vol advertised = 8.9 cc
valve relief advertised = 6.8 cc
piston relative to top of deck = 0.0
combustion chamber cc = 65.6
BDC vol = 706.2993 + 6.8 + 65.6 + 8.90 = 787.599
TDC vol = 8.90 + 65.6 + 6.8 = 81.3
CR = BDC vol \ TDC vol = 9.687:1

Cam was degreed and installed dot to dot.
Stood next to engine during pull to verify secondaries opened.

Click to expand...

You forgot to add in the area for the valve relief eyebrows.

Did you check piston to deck height with a depth micrometer?

And on the subject of cylinder pressure, did you have a 5 angle valve job done and have the valves lapped in?


I know I’m throwing a lot of **** at you, but I want to see you get through this. Success at your first engine build is important for your future builds and rebuilds.

Also its important to smoke chevies and fords at all opportunities given.