[Jay S]

I have done a little bigger .4176” profiles, I have spent quite a bit of time talking to Tim about them. They build a lot of cylinder pressure with pretty low compression when the LSA is narrowed up to 106* to 108*. I recall Tim saying some SBC with 1.5 rockers you could run as low as 170# seat, and a Pontiac can be as low as 190# with a 1.5.

I would probably only install it at 102* if the induction was pretty limited or compression was on the low end below 10. I believe I did a .4176” that was slightly bigger on a 108* LSA in a 9:1 455 and a 4000 stall in. As I recall 600 HP in a 455 with 10:1 or more SCR or more cubes yet installing the ICL at 106* makes it run the hardest. With a 320 to 330 cfm heads and bigger ratio rockers it can make about 620 to 640 HP at about 6K. Out of the box round port Aluminum head maybe upper 500s at just under 6K. With more head flow and compression on a friendly dyno it could probably go beyond 650 HP, but there would be better cams options at that point.

[Steve C.]

Another combo that I used a UltraDyne 0.4176" lobe solid roller.

462 CID
4.210" stroke
6.625" rods
JE custom pistons
'69 #16 d-port heads / depending on the bench 280-291 cfm
12.49:1 compression
264 / 271 @ .050"
.04176" lobe lift / w 1.65 RR
108 LSA
Victor intake / Carb Shop Stage III 750 Holley (rated 926cfm)
1-7/8" headers

First dyno session Feb 1998 - 626 HP @ 6400 / 611 TQ @4900


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