[Half-Inch Stud]

48s at 78 cc with Ram IV Valves. Not brave enough to eggshell up to 87cc.

My latest thought is to finish the shortblock, Top-end it, & break-in the cam on a super hobo stabilized engine Stand. Let it lay until Towncar engine is out and begging ready for the 455.

Meanwhile money gets committed to Dished slugs, or thick headgaskets. Possibly sell the Spare as a run-in flattop forged-crank shortblock. And look for a dished shortblock.

[Jay S]

Originally Posted by Half-Inch Stud

48s at 78 cc with Ram IV Valves. Not brave enough to eggshell up to 87cc.

My latest thought is to finish the shortblock, Top-end it, & break-in the cam on a super hobo stabilized engine Stand. Let it lay until Towncar engine is out and begging ready for the 455.

Meanwhile money gets committed to Dished slugs, or thick headgaskets. Possibly sell the Spare as a run-in flattop forged-crank shortblock. And look for a dished shortblock.

78 cc? I think that is the most I have ever seen for a 48. Tullip valves and the chamber grinding must have added up.

The valve reliefs in the piston photo look big and deep. How many cc they? Kinda sounding like the compression is more like 11.0, not 12. Might not have that far to 10 scr with the parts you have. Connect the valve relief and make it more like a tear shaped trough, and unshroud the intake a little more. Little things like what Stan mentioned a few post earlier add up.

[Half-Inch Stud]

Originally Posted by Jay S

78 cc? I think that is the most I have ever seen for a 48. Tullip valves and the chamber grinding must have added up.

The valve reliefs in the piston photo look big and deep. How many cc they? Kinda sounding like the compression is more like 11.0, not 12. Might not have that far to 10 scr with the parts you have. Connect the valve relief and make it more like a tear shaped trough, and unshroud the intake a little more....

Both valve reliefs cut into the Top-Ring land. But a Unibrow ? hmmmm
48s have been unshrouded;