Need intake valve overlap for 2.4 case. 2.2e pistons and 911e cam???? Help?

[marlinaness]

I am using a 2.4 case, crank and rods
I am using 2.2e pistons and e cam (same for 2.2 or 2.4)

911e cam was for fuel injection. I am using Webers.

Wayne's book says the intake valve overlap for the 2.2e is 3.0-3.3 and intake opens 29 degrees BTDC

Waynes's book says the intake valve overlap for the 2.4e is 2.7-3.1 and intake opens 18 degrees BTDC

Interestingly the 1967 911S with Webers has just a tiny bit more lift than this e cam, has overlap of 5-5.4, and opens at 38 BTDC.

so with nominally 9.5 or so compression with this combination, should I go closer to the 2.2 e as it is closer to the 911S with Webers.

Subject to experts saying I am wrong, I am going with the 911 2.2e.



Recommendations for this novice?

[larrym]

use the E spec - going more advanced will get you a lot of backfiring and reversion in the carbs - (BTDT) - and poor street torque - the S spec will get you high rpm and no torque below 3000-3500 - that's great if all you plan to do is go racing and never run under 5000 rpm

[marlinaness]

so, sounds like 2.2 e spec is the better option. The only good point for arguing is that the 67 S had webers and had a lot more advance compared to the two e specs which were fuel injected. Maybe it takes the carbs longer to move the fuel.

Nevertheless the 2.2e should be safe from a piston valve collision problem since it was "generally approved".
thanks
Marlin