So, I know many people buy a 68mm ported Throttle Body to increase incoming air flow. From what I understand, my stock L36 one has a 64-65mm opening and an L67 has a 69mm (I confirmed that one personally).

From what it appears, the L67 and L36 T-bodies are the same casting. I've spent some time and found for the "best" unrestricted air flow, looks like one should get a '97'98 L67 T-Body and do some "home modding". THat is what I am embarking on. The reason is that '99 and up has a "hump" that as I understand cannot be grinded away. Though, there is a "MAF" bridge that needs removed and the hole at the top for my '04 MAF will need bored out.

Now, I've collected some input and information to learn, the outlet surface on an L36 and L67 T-body is different. I determined I would have to fill in spaces on the back of the T-body and grind down the surface to match the mating surface on the intake.

After I learned this, I found a guy on a Bonneville forum that had done exactly what I have in mind for my T-body project (if you want to look at my goal, view the below thread and look at the pics):
http://pontiacbonnevilleclub.com/for...=528&view=next

I pulled an L67 T-body from a '97 Park Ave. So far, investment cost, $25-$30. I hope to finish this off with maybe around another $20 into it (give or take). But since I don't do any machine work and have limited tools (and time), this venture will take a while.

So far, I have the :67 T-Body stripped down. Tonight, I have a MESS of aluminum shavings (got the MAF bridge out). Lots to still be done!

 

You're changing and/or tuning the MAF sensor after this, right?

 

As I understand to get the MAF adjusted for the new air flow, I have to get someone with an HP Tuner to set that up (and that will take some $$$). So my plans are to do a larger list of mods and then get it all tuned.

I figure when I finish this T-Body, I can throw it on the car just to see what it will do (and if the car runs crappy as a result, switch back to the stock one until I am ready to have the entire car tuned).

Just my plans so far.

 

You do plan to open the inlet of the intake to match the larger TB opening?

 

At present moment, I have NO plans to change the inlet on the intake. From what I understand, the intake's inlet on the L36 is already big enough to accommodate my planned change. Keep in mind what I plan to accomplish is similar to the High Velocity T-Body sold from ZZP is a bolt-on accessory (and requires no change to the intake).

*** Progress UPDATE ***
I found a wicked cool Dremel bit to grind away the remaining stumps from the MAF bridge!! It was like a hot knife through butter (compared to what I was using).
Still some more work to do with the Dremel before the inlet of the T-body is done (then it's off to the outlet).
I think I need to clean up the aluminum shavings before I proceed!!

 

So the inlet on the L36 intake manifold is the same size or larger than a stock L67 TB? Never knew that.

 

The pic I attached shows the L36 intake-to-TB gasket on top of my L67 TB project.

Now, the opening going to the intake is a weird shape/size on the L36. I don't know how big the true opening on intake is (beyond that goofy mating surface).
I intend to fill the spaces on the L67 TB and grind the material to make a mating surface similar to that on my intake (and similar to my stock TB).

But that gives a little peak at what's going on.

The other pic was last night's progress. I think I have the bottom stump from that MAF bridge down to just where I need it. I need to bore the MAF opening to accept my MAF before I finish that upper stump (so I know how to make the surface match the MAF). I intend to polish the inside (before anyone comments about it).

 

OK, last night, my father gave me a hand by using his drill press and boring out the hold for the MAF. Sadly, did not have a drill bit big enough, so it was bored out using a metal rasp.
After that, further inspection revealed that the MAF sensor was not seating in due to a "step" from the plastic molding and a "step" in the metal on the base of the MAF (see pic showing the MAF, red arrows pointing to the steps).

This MAF opening is dealing with a difference in a '97-'98 L67 Throttle Body vs. a '99 to current. The MAF opening and steps in the MAF are slightly different between those models.

Now, when I compare what I started with on the L67 Throttle Body to the original MAF opening on my car now, I can see some difference in the casting (the walls around the steps in the MAF are thinner in parts). Using the Dremel, I grinded away until the MAF sensor fit AND I could put the bolts in without stressing the MAF or possible cross threading the bolts.

I admit, I was dis-mayed at myself, I had problems with fitment and kept thinning the walls out (more then I should have). When I further studied the situation, I felt so stupid to find I was really battling with the step from the plastic part of the MAF (I hit it just a little more and got prefect fitment). The MAF seats and doesn't rock around (even with out the bolts). But just to make me feel better, I will put a little JB Weld in to improve the walls of the MAF opening (get it to be a better fit).

I will probably be messing with JB Weld there and on the back side of the Throttle Body soon.

 

I found a good "before" pic of the MAF opening on my L67 Throttle Body....

 

More progress. As many people know, the outlet on the L67 does not mate the same as the L36 (the L67 has a circular mating surfaces, the L36 is more oval shaped for lack of a better description).

In hopes to self grind the L67 throttle body to mate with my L36 intake, I had to fill in the surrounding gaps. I did so using JB Weld (before anyone knocks it, I found I am NOT the first to use it for this application and it should work fine).

I also chose to fill the port that allows coolant into the T-body.

Attached are pictures from tonight's play time