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  View original topic: Advise on enlarging CB CNC Street Eliminator Chambers
Alexander_Monday Wed Aug 13, 2008 11:29 am

Just got my hands on a set of CNC Street Eliminators 44 X 37 X 90.5/92, and I am quite impressed with these heads.
Of course they are in need of a little hand clean up, and I also want to enlarge the chambers ~ 5 CC. My goal is to
keep the quench areas as large as possible, but I do not want to screw up the chambers while doing so. I will be using
a 3 lobe twisted rotor Magnuson ( aftermarket Eaton ) supercharger on a 90.5 X 82 engine. Lower rpm is not a major
concern, as this is a weekend warrior / V8 embarrasser and positive displacement blowers are known to really
pump up lower / mid range. Cam card is below and I will be running 1.5's. I will be running 6 to 10# of boost
depending on what intake charge temperatures I end up with, and 10 to 15 if charge cooling works out to be feasible.

In the picture below it is obvious I need to clean up the sharp edges at the top of the chambers, the tooling marks,
and the small areas right at the valves that are shrouded ( red arrows).

1st question is ( blue arrows ):
A) Should I maintain the slope of the chamber walls but enlarge the top and bottom of the chamber ( move the walls out ) ?
B) Reduce the slope of the chamber walls to more horizontal and leave the start of the walls ( valve end ) where they are?
C) Increase the slope to more vertical enlarging the bottom of the chamber but minimum reduction of the quench areas?
D) I do have the infamous Berg hemi cutter as a last resort, but do not want to reduce the quench areas that much.
E) None of the above.

Next questions are:
2) Should I give more bias to removing material toward one valve or the other and which one?
3) Should I give more bias to removing material on the spark plug wall, or the opposite wall?

Whew! That ought to be enough for now. Of course I am aware that I will most likely end up with varying opinions, and
I wish to digest them so any reasoning behind your answers would be appreciated, and if it is actual experiance or theory.

Gentlemen, start your opinions. :D



And a different angle to give a little more idea:



A couple of intake pics if they make a difference in your opinion:





Cam card:


A.J.Sims Thu Aug 14, 2008 7:03 pm

Quote: 1st question is ( blue arrows ):
A) Should I maintain the slope of the chamber walls but enlarge the top and bottom of the chamber ( move the walls out ) ?
Yes.
B) Reduce the slope of the chamber walls to more horizontal and leave the start of the walls ( valve end ) where they are?
No.

C) Increase the slope to more vertical enlarging the bottom of the chamber but minimum reduction of the quench areas?
Yes.

D) I do have the infamous Berg hemi cutter as a last resort, but do not want to reduce the quench areas that much.
I would just open the top over the plug.

E) None of the above.

Next questions are:
2) Should I give more bias to removing material toward one valve or the other and which one?
Some on the intake but more on the exhaust do to your use.

3) Should I give more bias to removing material on the spark plug wall, or the opposite wall?
Spark plug.

Link to a video.
[url]
http://www.lowbugget.com/chambervideo1.html[/url]



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