7.18 to 1 compression ratio

[46yblock]

Yesterday I made an accurate measurement of the piston to deck height on my pulled motor. I knew it was huge a couple years ago, but now I know how huge: .124 inch! That calculates out to a 7.18:1 static CR. It gets worse, because there is a 270 degree duration cam in place. This is a confused motor.

[312]

it shouldnt be near that much.what have you got for rods and pistons.

[46yblock]

.080 OS pistons, probably the type with .040 piston to deck clearance, rods will be known in a couple days, but most likely C1TE or ECZ. Rods were resized so they likely lost some length too. You can pretty much add it up: wrong rods, .072, piston deck heigt .040, resizing loss .007 (depending on how bad they were out of round). Then add in a .045 gasket, and wallah, flathead specs!

That low compression figure is with 69cc 113 heads .

[46yblock]

The rods are ECZs. The engine hasnt been apart since it was built for me in 1993, but for various reasons has very low mileage. Luckily the balancing paid for was done. Rods and pistons look like new, and can be reused as is. The rods were resized. Bores will clean up with a bore brush. From what is visible of the cam, it looks like new also, and beefy. The cam needs to go to Mummert for analysis, since a cam card was never received, and its manufacturer went out of business in the 60s or 70s. Looking down through the motor, it is clear one lifter was not rotating (the lifters were reground). I have a new 312 crank with 292 mains ready to go, so the motor will live to see a better day.