[242177P]

Nice seeing the 2.11 clear that small bore. As Squidward says,
deck clearance will change depending on casting used.

Now here's the $60,000 dollar question: at what point do you
sacrifice valve lift for compression? There's like 20cc worth of
difference between the late 6X-4s and early 17s (IIRC).

And if it's just some bowl blending, you could add a big valve
to a '69 47. There's enough variables to make one's head spin,
but it's all so very intriguing.

[srmmmm]

Originally Posted by 242177P

Nice seeing the 2.11 clear that small bore. As Squidward says,
deck clearance will change depending on casting used.

Now here's the $60,000 dollar question: at what point do you
sacrifice valve lift for compression? There's like 20cc worth of
difference between the late 6X-4s and early 17s (IIRC).

And if it's just some bowl blending, you could add a big valve
to a '69 47. There's enough variables to make one's head spin,
but it's all so very intriguing.

Going to a 4.25" stroke, the 6X-4 heads gave me a comfortable CR of about 9.3 to 1. I've had no issues running 92-93 octane in it as a result.

[Squidward]

Originally Posted by 242177P

And if it's just some bowl blending, you could add a big valve
to a '69 47. There's enough variables to make one's head spin,
but it's all so very intriguing.

That's what I had done to the 47's on the 400 in my Lemans - big valves. Paul Carter did those heads, and said his previous testing showed an increase in flow numbers.