I am thinking of buying an RB 6-port manifold and holley 600 carb from a friend. I looked at it tonight and the manifold has been cutt at the top were it mounts to the carb. The normal holley flange has been cutt away around the circles so that it lookes like a merged racing collector. I has a point in the middle and the walls curve down in the middle and are knife edged. It is as though you are looking at a race header collector when you look down through the carb inlet path. Why is this done? Has anyone heard of this being done? Does this damage the velocity of the ports at the top of the manifold, right under the carb. I would think that this would slow flow at the venturies.

 

I wouldnt be able to help you but I really think the people who can would ahve an easier time if you provided a pic. JUst a suggestion.

 

if I had a pic, or a way to do that, I would. Just look straight at a merged header collector and you'll see what the top of this intake manifold looked like when I looked down in it.

 

It sounds like they converted it over to a "single plane manifold" design.
The V8 carb guys should understand this.
In theory, it makes for better top end power since it balances out all the runners.


-Ted

 

The way he described it, it sounds just like someone ported the runners the same way someone would just knifeedge a throttlebody.

 

no the runners at the top have been cutt away to form a large plenum with a spike in the middle. Someone on another board has done this to his manifold so that he can use a vacume secondary carb instead of mechanical. I am curious as to what this will do to the power band, since I have S4 internals and can't rev past 7500 or so. If the internals can stand more, let me know I really am not sure what they can stand, I just know my stock FI cutts fuel at 7500.

 

bump