I believe that is an 8.1L/496 intake manifold.

That looks like the 8.1L/496 intake that Tyler Crockett had for a little while. There was a Advantage boat over at LOTO for sale with one just like that a few years ago.

You may have seen this however thought I’d post anyway. Something not discussed much.

https://www.yellowbullet.com/threads...or-na.2657091/

http://www.rockettbrand.com/download...low%20Burn.pdf

Looks like this is angle cutting the heads? In effect reducing chamber volume? That has been going on for a couple decades I am thinking. Big Chief chambers were like 75-80 cc's and didn't like timing much over 30 deg?

For sure - just doesn’t get brought up much. Not that I’ve seen here anyway.

[QUOTE=bob;4816312]Looks like this is angle cutting the heads? In effect reducing chamber volume? That has been going on for a couple decades I am thinking. Big Chief chambers were like 75-80 cc's and didn't like timing much over 30 deg?[/QUOTe
when they angle cut the quench it's done on a 5 axis because it's only the quench in the combustion chamber that gets cut. Not the whole deck.

So in effect it actually increases the volume of the chamber so it will lower the compression.

As KWright said. They're not reducing chamber volume, actually would increase it slightly.
They sort of "Hemi" it so to speak. Angle mill just the flat areas of the chamber, towards the center.

I used to have a guy put my heads on a flow bench and put a piece of yarn in the air path and watch to see where the circular pattern was in the chamber and then re-configure squish area to get center of flow to be in center of chamber. Did each chamber. Not really sure if it was all that important but it sounded good at the time.

FWIW, Arizona Speed and Marine from what I can come up with. Old thread regarding one.

Arizona Speed & Marine 625 HP engine

And the most recent thread that I remember that picture from. (Which was a pure sh it show)

idle timing with Holley HP efi

Anyhow, back to Tunnel Rams.