2004 Chevy Monte Carlo SS

Port Matched Lower Intake
Prepped Spring 2011 - Planned install later in Spring 2011

Project Background/Research - I've done a lot of reading about performance mods on the www.PontiacBonnevilleClub.com, I found message threads about the group there discussing in detail about casting flaws on the L36 lower intake exit ports.   As a result some of the guys discussed "port matching" the exit ports on the manifold and described in detail the process they used.   The idea behind "Port Matching" is NOT gasket matching (if you attempt to gasket match, you must then gasket match the heads.   Port matching is simply modifying the exit ports on the lower intake so they better match the shape/size of the connecting ports on the heads.

The goal is to make the ports more rectangular (but not to disturb the injector boss, which is a small little bump out in the corner).   The mesurements should be 1.9 inches by .9 of an inch.   To better illustrate, here's the pics to help explain.   The one on the left is a port that has not been modified (I added lines to help explain) and the port on the right is a completed port.   The lower pic shows a measurement from the widest part of the port (in this case the measurement was .906 of an inch).   When matching the ports, you do not want to exceed that maximum distance.   Another item tough to capture in a picture is that you want to continue that matching up the runner a little bit (otherwise, you will have a properly ported exit, but still have the same bottle neck inside the runner).


The guys on the Bonneville forum that have done this process appear to have this method down!   There is so much information on the subject and claims of this mod being one you will instantly feel, I decided to try my hand at it.

I want to give a special thanks to the many people on the http://www.pontiacbonnevilleclub.com that shared information AND helped answer some of my questions on the topic.   I think with every thread I read on the subject, WILLWREN was the most common guy chiming in with some great info.   Thanks again guys for your advice, guidance and support with this mod!

WARNING!!   Please Read - If you decide to do what I have done here, wear safety glasses/goggles!   I will not be held responsible for mis-haps that result from attempting to recreate what I have done here.

The proceeding links display the progress of port matching a lower intake manifold for use later this year.

-->Port Matching Project Description
Donor Lower Intake
Finished Product
Updated Finished Product

2004 Monte Carlo SS Page

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