panic
ok, lets try this one on for size...a Schneider 289F vw Type 1 grind, installed 6 degrees advanced...
240/264 duration at .050", .380"/.404" lift at lobe (.536"/.570" calculated with a 1.41 rocker ratio, .518"/.552 at valve, factoring .018/.018 lash), intake opens 20 deg BTDC , closes 40 deg ABDC, exhaust opens 64 deg BBDC, closes 20 deg ATDC, overlap 75 degrees, 106/106 lobe centerlines
RPM Range:
2800-6600
Static compression ratio of 12.22:1.
Effective stroke is 3.82 inches.
dynamic compression ratio is 11.06:1 .
dynamic cranking pressure is 240.44 PSI.
dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of PSI is 11.06 :1.
V/P (Volume to Pressure Index) is 198
CNC-dude, the heads that i have are the 2194819 small-port, closed chamber variety.
i saw the modified 235 head on e-bay with the downdraft intake ports and i'm aware that the Rajo's were modified somewhat similarly and i had thought about that approach as well, but it doesn't solve the crappy exhaust port issue. it's possible that the gmc heads flow worse on the exhaust side than 235 heads do. the head bolt bosses could all be counterbored to use shorty allen head capscrews and one could raise all of the ports as panic described, plunging into the head at a 30 degree angle on a horizontal mill at all port locations and brazing in the weld-ell's. a new flange would also have to be brazed on.
Last edited by garagepunkfan; 02/26/10 08:35 PM.
