'04 Monte Carlo SS - Port Matched LIM

2004 Chevy Monte Carlo SS

Port Matched Lower Intake
Updated Finished Product

OK, just when I thought I was done and this intake was awaiting installation, I decided to do a couple other things. Admittedly, some of this was more input from the folks on the Bonneville forum. First, I swapped the "stove pipe" for the narrower pipe. The purpose behind this is to help reduce heat damage to the nylon upper intake manifold. The next item, since I have the coolant pocket on the throttle body blocked, this reduces some of the coolant circulation in the lower intake manifold. The compensate for this, I expanded the opening on the coolant bypass. But, you have to do more then simply expand it, you need to get to the center diverter and remove material from it (otherwise you still have the same volume of coolant flowing, as it can only flow what the bypass plate allows). I decided to round mine a little (even though it will probably never be seen again, it looks nice in the pictures I took).

Last item and perhaps it's just overkill, blocking the ports on the lower intake that actually flow coolant into the throttle body. Even though the pocket on the throttle body is filled in, I decided I just don't want the coolant flowing into the upper intake at all. I bought stainless steel plugs from the hardware store, tapped threads into the holes, put some JB Weld on the threads of the plugs and screwed them in until they were flush and wiped the excess with a paper towel (once set, I will do a final cleaning).
The big concern some people have about blocking those ports on the L36 is that in the winter you may experience the throttle plate freezing/sticking in place. I know we can have some bad winters, but I know my current Grand Am (3100, so it's NOT the 3800 L36 my Monte has) does not heat the throttle body at all. I've also heard some speculation that heating the throttle body has something to do with fuel efficiency. I'm not sure, so I am admittedly taking a bit of a gamble. Lastly, this is overkill since I blocked the coolant pocket on the throttle body itself.

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

2004 Monte Carlo SS Page