266 versus 276 CI?

[Tim Ayers]

To be clear, there have been a couple of errors in calculating total displacement in this thread. The engine the O/P is describing (3 3/16"+.030" bore with a 4" stroke) is 260 ci, not 266 ci. The classic hot rod "3/8 X 3/8" flathead (3 3/8" bore and a 4 1/8" stroke) is 296 ci, not 286 ci.

If my math is correct, my engine at 3 3/8" +.030" x 4" is a 292.

 

[KiWinUS]

^^^^^^291.39ci.

 

[tubman]

I'm with "Ol' Ron" in liking a 258 ci flathead (3 5/16" X 3 3/4"). Three more cubic inches than a 4 inch Merc crank will give you with a stock bore for a lot less money. (Lower piston speeds, too; not that it makes much difference with a flathead.)

 

[frnkeore]

The term "spindly rods" may have come from someone when looking at a flathead rod

 

[Phil Gillespie]

I'm with "Ol' Ron" in liking a 258 ci flathead (3 5/16" X 3 3/4"). Three more cubic inches than a 4 inch Merc crank will give you with a stock bore for a lot less money. (Lower piston speeds, too; not that it makes much difference with a flathead.)

Above is exactly what I am running in a 46 Merc. Coupe. Just running a single 97 Stromberg carb up a couple sizes on jets and PV and standard NOS heads with 45 thou piston to head clearance.
To date have approx 750 miles on engine since full rebuild. For my street use it suits me well.
Phil NZ

 

[Tim Ayers]

^^^^^^291.39ci.

Would you help a brother out and let me round up? 292 sounds so much better than 291.

 

[raybee]

Back in the day, 3 3/8 was a standard overbore for a hotrod. Along with the 4 1/8 crank, you had a 3/8 x 3/8 engine or 286ci

Back in the day, there were a lot of good blocks around.