Any port matching you do of the throttle body outlet to blend to the uim won't require any tuning changes. Nor should opening the snout outlet to the main chamber.

I think bonnevillepro.com is having some site issues, that may be why some of the links are not working (same guy posted the info also on pontiacbonnevilleclub.com, if I get a chance I'll see if I can find that link).
But as far as evap and vacuum lines, don't worry about the links too much. The 45* fitting I have on the snout was an idea I got from that Bonneville link. But the pcv hose going from the stack on the top of the uim and into a fitting I put in the side of the throttle body was an original idea I had (others typically have gone under the throttle body).

As for where I got the fittings, I checked like crazy locally and could not find them anywhere (now I see them at the local parts store). Some of then you can get in the plumbing supply isle at hardware stores (good for 90* and 45* fittings, but they sell ****** fittings instead of the bead top ones I used). I ended up getting all mine from eBay. I have no idea of stainless ones. Are available.

 

Okay thanks thats really good to know. And alright ill just keep looking into that but yeah no im doing what you did to a T with the pcv and evap stuff. I hate what all the other people have done for solutions (ive been reading other write-ups, not nearly as good as yours i might add) and i REALLY like your solution and how it works and functions and even looks. So thats why im trying to figure out what exactly u did with the fitting in the TB because thats the method imma use, way easier than messing with the stove pipe and all that. So ill try and find some fittings like what you have for this because ik that your set up is working just fine and will go together alot easier in my opinion. Really the only difference between our setups is that my UIM and TB are gonna have more of a "Billet" look and the Adapter will be blue most likely and i might use different style hosing and stuff but you found something that works and thats what im sticking with. Im so glad you did this write up. And im very grateful uve been helping me so much.

 

No problem on the write up.

I was anxious to share this project and the creative way I found for the PCV system. I had this project on my "to-do" list since January of 2013 (but did not get to REALLY dedicate time to it until this year). In that time, I studied like crazy the PCV set up and struggled to find an answer that felt "almost" factory. I searched all over the Internet and since this was such a rarely discussed mod, not many options were presented. The day I found I looked at the parts and things clicked on how I should do the PCV system (the way I am now doing it) hit me like a ton of bricks and with that famous thought "now why didn't I see that earlier". On the throttle body, where I drilled and tapped for the fitting, that used to hold a bolt for a support bracket that no longer fits. Lots of meat to drill and tap, not to mention it's just past the MAF and before the throttle plate (perfect spot in my opinion).
FYI - There is a 90* piece and then the fitting. If you try to get 1 piece to screw in, it will not clear the area for the throttle position sensor.

And making the adapter bracket blue I think will flow nice with your "Black and Blue" theme. My motivation for the black adapter was concern if the three metals would "flow" in appearance. Making the plate a different color ensured if they did not, the eyes would be distracted.

 

That is amazing information to have thanks so much that right there makes this alot easier now ik I just have to find a bolt in that area and drill/tap it to fit a fitting for a hose! I was thinking of maybe using a smoked translucent tube for the connection between the TB fitting and the UIM stack for a slick custom look. And yeah that's exactly what i was thinking with the Adapter Plate! That it would be good area to kinda break up the flow, something that catches your eye as you go from one end of the UIM to the end of the TB and gives the setup a custom attitude. And you did just that with yours! Your set up is very clean and "classy" if you will. You've pulled of a classic look with custom attitude!


One unique thing I'm also doing that I haven't seen, is doing something about the finish on all the black sensors. So that rather than the big ugly black plastic ends blocking the view of that new billet finish of the TB, theyll add to it! Idk what imma do tho. I thought of vinyl wrap, but that maybe too challenging to flex it to that odd shape. Maybe on the top of the MAF I could. Maybe really thin sheet-aluminum and make little covers that go onto the backs of them that have sides to make it look uniform, and then I will be replacing alot of the black wire loom with blue wire loom so theres the rest of my blue accent.


I would also really like to have that crossover pipe have a polished finish on the outside. Wonder if I can machine that metal shielding to look like the finish of the power log. Maybe custom make a crossover with custom bent stainless pipe and some stainless flanges sold on ZZP and weld my own. After all its a big piece that is really visible and it would match the plog alot better. Ik it'd look nice in the engine bay, like the look of the stainless headers without paying so much. But I'm rambling lol.


thanks again Jason. I look more and more forward to this project every time I get a response from you. And I will be very anxious to do a write up on this project with lots of pictures! And none of it would be possible without you taking the initiative to do it and share it!

 

I don't think I'd mess with trying to polish the crossover. I'm not sure if all members shared this issue, but my nice shiny stainless plog has discolored after use. It's a lot of heat that flows directly out of those heads. I think if you were to polish that stuff, you may end up disappointed. Maybe have it sent off and ceramic coated? Or fad up nice heat shields....

 

dosent that not happen as much if you simply remove all oils and grease off the metal (polish it with some simple chrome hand polish) before you first drive it?.. Everytime i see a plog put on for the first time or a dp or headers, theres finger prints all over the fricken thing, and then it gets hot, grease stains the metal. I could be wrong.. But i polished my DP after it was installed, my grandpa said itd discolor right away, drove with it for awhile, put it back up on the rack to retighten the bolts after a few days, still looked like new. Ive seen headers on these cars that didnt look terrible. If they get a little blue i dont care that can even look cool. But if theyre clean and polished, theyll stay shiny. From what ive read anyway. When people are finished putting polished parts on, they should polish them totally clean, not touch them without gloves, and itd look a lil better. Maybe. I could be totally wrong here tho lol so. Well see. Right now im just worried about polishing my UIM and TB to a high shine, billet finish havent bern able to find anyone with a L Series TB thats fully polished. So im looking forward to see my results! Ill post pics of the parts when i get them and start machining them.


Oh, and the brass fitting you used where 3/8inch right? For both the thread and the barb fitting?

 

Jason, Hoping after all this time you will see this. I have 03 Impala @ 117K miles, just noticed I was losing coolant and doing a UIM/LIM gasket replace plus an L26 aluminum top.

I saw your "good" and "bad" pics of the UIM. I happen to have one of the "bad" ones, brand new from Amazon. So it appears on the bad version the throat of TB is flattened out as it enters the chamber and rounded out on the good. However and this is a big however, the reason is, that the PCV port is running straight up internally from just a bit forward of that flattened area of TB, this encroaching into the throat and the location of that PCV access port is going to be the same on any version of UIM as it has to match the location on LIM. So even on a "good" UIM you are still (or should) have a "bulge" and narrowing of the throat by the internal PCV passage near the end of the throat. I would think the only real difference is that this non circular portion of the bad UIM was ported out some, so to speak, just after it passed by the PCV passage way on the good UIM, making it look effectively round.

On top of that, this non circular area on the bad UIM doesn't really matter as the plastic intake runner there follows it about 70% of the way so circular or not, the air is partially blocked by the insert. I guess one could argue on the "bad" UIM that the straighten area is intentional to keep the air from the throat hitting the side of the first insert runner which would cause back pressure and turbulence, I would think that would be the worst case. The bad UIM seems to be ported (although in an unconventional way) to keep the throat air from hitting the intake runner. I think that's better. Same concept as what you show when you took out the step of the throat intake caused by putting the adapter plate in front of it. It keeps air from hitting a block in front of it.

Can you verify that you still had sort of a narrowing of the throat near the PCV passage way, I can't see how you wouldn't have that but I could be wrong.

For the runners guides in the plenum area, I can see how the good one guards the beginning of the air intake for the insert, possibly so its not stealing air or otherwise from the intakes on the other side. But by same token it also blocks a path of air that could run down the entire manifold . Either way could that really be that much of a difference? Seems air is going to be very turbulent in there anyway.

Now as far as labeling these good and bad, with all due respect, could you be wrong on that. Yes, circular on exiting the throat does naturally seem better until you realize it hits the intake runner.Looking at the numbers the good has lower numbers and bad has higher number. I would think generally that a higher number would be associated with a later change. Now all later changes are not necessarily a good thing but my bad UIM has a runner with date code Aug 10th 2008 and the aluminum UIM has 9/11/08 time 19:32 stamp into it. Whats the date on the good UIM. Unless we can see that GM changed it back to what you refer to as good that possibly this was intended changes, again that doesn't make them the best. Definitely something changed. along the way, but why.

Any other info on why your referred to the 2 different UIM's as good and bad. I'm about ready to install mine but will probably wait until I hears some feedback from the group. Considering that I'm just going to drive this like a Granny (well, maybe like a angry, crazy Granny) anyway I don't think either one would make a difference in my case.

Great post by the way, probably had more questions but will do that in another post.
Cheers-Don

 

Hi ColdWarVet607,

I'll try to provide as many answers as I can and if I miss anything, let me know and I'll try to come back around.

When I used the terms good vs bad, this was a focus on the difference at the throat between the two UIMs. I actually had both UIMs on my workbench at the same time and did a bunch of comparisons. I know of the date code, but I never thought to compare those (and I don't have them captures and with the texturing on mine, that code is long gone).
Both of them do have the same PCV pipe going through in the same spot as you noted. I don't know how, but somehow on the "good" UIM GM did not obstruct the opening of the throat as much for that PCV pipe. Maybe the PCV pipe is bent/molded better in cased in the aluminum to allow for a better opening, I'm not sure. But I do know for certain there the opening and throat passage on the "good" is wider through out the travel then the "bad".
Also, the "fins" in the roof space of the UIMs differ. In the "good" UIM, those fines are molded exactly the same as the fines in my original plastic UIM I took off my Monte. Looking at my pics, I have an incorrect pic posted (and not sure I have the correct one anymore). Look at the pics there are showing the view going into the snout (my statements about those pics was about "hogging" that opening). The first pic is the "bad' UIM and the second (of my "hogged" out effort), you can see the fine differences (the "bad" look like an upside down V and appear to consume more space, I honestly don't know if it's a problem or not, I've heard of one person who completely removed those fins).
When you mentioned the the runner insert, that is something I did not discuss. I am running a ZZP HV3 insert, with that, you discard the original intake runner. So for me, the obstruction from the running makes no difference.

Well the bad work for you, I am certain it well. I have no idea if you well have any real performance differences. For a completely stock car, I'm sure it well be just fine.

I hope I hit on all of your questions. If not, let me know.

 

Hey The_Maniac

Thanks for the original posts and the reply. Looking back at your pics through the snout I can see how well rounded the Good UIM is. Originally I did notice the picture above it had the PCV tube bulge like mine but thought you grinded that out in pic below.

Looking into my UIM throat if I follow it I would be ~50% into the inner PCV tube if I grind that out. (tried to ad pic but will only allow a URL link, not to my laptop? )But if my throat was tapered just a bit on the input and if they reduced the size of the uneeded bulge it looks like it would be possible to sneak by that inner tube without exposing it. Possibly thats what happened on your good UIM and an smaller diameter? Doesn't matter.

You got me motivated to do some hogging out! Hey if you are not going to go all the way why bother going at all. I'd get rid of some of the inner fins as well and use the HV3 insert. Looking down the throat of my L36 plastic UIM its nice and wide oval as it enters the plenum but like I said in last post, The runner for cylinder 6 blocks the wide side of the TB exit to UIM so there is little point to having it that wide. Im wondering if that influenced this bad UIM design. But GM wasn't thinking about an HV3 insert which makes lots of sense and the only way to go. Why didn't they do that if HV3 works so much better, guess thats a different thread.

So what do you think about me grinding down and exposing the inner PCV tube. A work around would be to fill it in that area.

I get the PCV pathway by drilling into the side of UIM near the bottom where it just comes from out of the LIM, theres plenty of metal.

I planned on routing the PCV tube to a 45 degree fitting, tapping into the plug on the bottom of the TB that tube would route nice and out of site, I just need to be careful of ERG pipe.

Anyway thoughts on filling the exposed PCV tube area with JB Weld?

Whats best approach to do the grinding. Haven't done grinding on Aluminum yet. Can't put the UIM on my drill pres for this. Is a dremel good enough, Start with metal rasp bit and then to stone?

Liked the re-routing of evap and fuel reg hoses. Will do this. Is that a RA adapter you used. Any reason to use RA rather than straight. Any issues with centering it rather than going higher as you did?

Thanks alot for the help, 90% sure I'll do this, if I do I'll post results here. -Don

 

Right now you are a "new member" and posting pics are restricted to limited locations. You become a full member after 5 days and 10 posts.

I privately wonder if the UIM differences had to do with product lines. I wonder if GM had testing between the two and maybe one was more performance driven then the other. But that is 100% pure speculation.

It was actually another member on this forum that spotted the first L26 UIM I was going to use did not look like the one he used and he shared pics with me. After that, I decided to hunt that one down.

Personally, I would hunt down the better intake (it may take asking for detailed pics from eBay sellers to confirm, the roof fins should tell the story right away). The opening into the main chamber was not perfect, but it was better then the one I dubbed "bad". At that point, depending on your goals dictate if it needs any hogging or not. My goal was the smooth the air flow transitions from the throttle body back.

Since you already have this UIM, if you are intent to keep it, you can get daring. You spoke some ideas I was having before. If hogging that part of the UIM does break into the PCV pipe, I was thinking of closing it off (possibly a combo of a threaded plug and JB Weld) and then drill/tap a new exit for the PCV and install my own fitting. After I was done hogging it out, I saw no signs of breaching the PCV pipe, so I used the original exit.

As for the throttle body part of the PCV, I opted to stay away from the under side of the throttle body for tapping into. I know a member here that did that successfully and I've seen others that also did it successfully. When I did my switch, I was tempted to tap into a tube that runs to the top of the throttle body and had a plug in it. This location is shared with the IAC. I was concerned it might cause issues with the IAC properly providing air at idle (I later read someone did this without issue). Instead I found I could drill and tap into the stump that was previously used for a mounting bracket I no longer required. To my knowledge, I am the only one to have done that and it worked great and was easy to connect a piece of rubber hose to once I had the fittings on.

Now, for the "hogging" of the UIM, my primary tool (and it was difficult to work with because of spacing and only having two hands) as a rotary rasp that chucks into my drill (got a Vermont one from Home Depot). For all the finer work, it was a variety of metal grinding/de-burring bits, sanding drums and buffing wheels for my Dremel. If you never shopped at WidetSupply.com, I suggest checking them out for Dremel goodies.

If you want to explore more info about the 3800 Throttle Bodies, here is the info about the first one I modded prior to the L26 swap:
'04 Monte Carlo SS - L67 Throttle Body

I've heard some people run a stock 3800 without the intake runners and get a performance bump. ZZP's HV3 is part of three pieces they recommend working together (the HV3, the ER Rockers and HV Throttle Body, I have the first two and I am using a modded L67 throttle body in place of the HV Throttle Body). I think it's a matter of GM found where they were happy at with the engine's performance, leave the rest to the aftermarket (GM has bigger toys to tweak).