i have a forged 400SBC i built when i was in highschool.


back then, i ran out of money after i built the bottom end, and i ended up having cruddy top end parts on it.
now, i have a entire topend/valvetrain thats going to be great..


but i forgot the size of the dish on the pistons


if i got a piece of plexiglass and sealed it to the top of the motor,
then with that piston at TDC, used a big syringe (im talking huge) to inject oil into the cylender, would that give me a accurate enough displacement amount so i could decide what head gaskets to use?


i dont see any reason why it wouldnt work, but if you do, please post... also, will the oil cause any adverse effects? i mean getting trapped between the rings on startup or somthin...?

 

That method will work. Water is easier to work with thou.

 

Don't use water.. you don't want to get any water inside the engine. Oil would be perfectly fine.

 

You can use water if you seal the gap between the piston and cylinder wall with some common petroleum jelly (vaseline) then you can suck the water out with a shop vac when you're done. Work the vaseline in real good with your fingers. then wipe out the exess.
The little bit of vaseline will not do any harm to the motor.
I use an old CD ROM DISC to cover the cylinder top
while cc'ing. The hole in the middle is real convienient for pouring the water throu to fill the piston dish.
You can buy a 100ML (100cc) graduated cylinder to measure the water volume, at most good pharmacys.

 

Measure the depth with a straightedge and feeler gauges; measure the diameter of the dish; volume = pi * diameter * diameter * depth / 4; add or subtract a fudge factor of a cc or 2 for valve reliefs, curved edges around the outside of the dish, etc.

 

Quit playing around and get out the Play-Doh. Make an impression of the piston dome, let it harden (can anyone say "microwave" then make an opposite impression in some fresh Play-Doh. Measure the volume in the depression made in your mold.