I have no idea where the intake valve closed on the 151 cam, but I would think somewhere around 40 degrees ABDC or maybe a little later. It had to close later in order to modulate the cylinder pressure with the relatively high SCR. If you use a short closing point with a high SCR, the motor will make so much cylinder pressure that nothing short of alcohol or race gas will allow operation without detonation. It's a juggling act, you need to make enough cylinder pressure to generate good horsepower and torque, but not so much as to need race fuel and not so little pressure that the motor is a pooch. Generally speaking, 35 degrees ABDC works well with 9.5:1 SCR, making a good DCR that will operate on pump gas without detonation, but will still make good power.

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