Gear heads question? Calculating engine displacement?

Anyone have a way to figure out engine displacement on a motor without pulling the heads?

Outboard, car, tractor???? Serial number and engine lookup if possible

chamberschamps wrote:

Anyone have a way to figure out engine displacement on a motor without pulling the heads?

The most accurate way is to measure the actual displacement using a liquid, usually water is used.
(A)The piston needs to be at top dead center with the valves closed. From a known amount of liquid, fill the cylinder with your liquid. Make note of the volume used to fill the cylinder.

(B) The piston needs to be at bottom dead center with the valves closed. Again from a known amount of liquid, fill the cylinder with the liquid. Make note of the volume used to fill the cylinder this time.

The difference between the volume used in “B” minus the volume used in “A” is the displacement for that cylinder. Take that, times the number of cylinders and you will have total engine displacement.

This is the way we checked racing engines so as to not be over the allowed engine size, for any given racing class. Our engines were always bored and stroked so serial numbers and such meant nothing as to actual displacement generated by any particular motor.

Thanks guys. It’s a 400 Pontiac big block, but it’s “supposed” to be bored and have a 455 crank (from the guy who built it). I’ve never really cared in the past but I’m going to sell the car and want to be able accurately give the displacement.