Wanted 3100 Lower Intake Manifold

[robertisaar]

I managed to crack mine tonight removing the heater core quick-connect fitting(pulled out some of the threads as well). I already have a full gasket set otherwise I would have taken the opportunity to throw on large-port manifolds.

I'm seeing a couple on ebay for ~$40/shipped, if anyone is willing to let one go for less than that, please post/PM by Thursday since I need to pull the trigger on something by then, I figure someone has done a large-port swap recently and their old LIM is taking up space. depending on what the local yards are charging(one is always ridiculous but tons of stock, the other has a tiny lot but reasonable prices), I may look at that route as well if the weather doesn't fight me.

looks like the 93-97 3100 lowers are all identical, 98/99 appear to be different according to the part numbers alldata is returning to me. probably when the change to the pressed in fitting occurred?

[Purple pit]

Damn....three years of holding on to my old one and just a few months ago I gave it away for scrap. Snag one of those Ebay ones.

[45es]

Can't help with the manifold but I do have a question for you. You say you already have the gaskets so I suspect you could tell me what is the correct brand / part number for the metal reinforced LIM gaskets? Thanks.

[3400-95-Modified]

I just saw one in my garage, pay for shipping to get it out of there....
I think it's a 96 or 95 with the threaded heater pipe outlet.

[robertisaar]

Damn....three years of holding on to my old one and just a few months ago I gave it away for scrap. Snag one of those Ebay ones.

due to a recent discovery, considering a new plan, details below.

Can't help with the manifold but I do have a question for you. You say you already have the gaskets so I suspect you could tell me what is the correct brand / part number for the metal reinforced LIM gaskets? Thanks.

yes and no... I ordered a Dorman 615-206 kit, which is listed as being used with the older style rockers.... well, it isn't. I should have looked harder at the pictures because after opening the box and getting a good look at them, it is clearly meant for large-port applications. it does have aluminum framed, black rubber LIM gaskets though.

I just saw one in my garage, pay for shipping to get it out of there....
I think it's a 96 or 95 with the threaded heater pipe outlet.

considering, but I may have a new, more fun plan of action:

since I already have large-port gaskets..... and I saw a 3500 G6 in the yard a few days ago.... is there any reason I shouldn't pull the UIM from that and the LIM from one of the dozens of 3400 grand ams nearby? these would be going on an otherwise stock 3100, so I assume it would push it up to the large-port 3100 range in terms of power.

[Purple pit]

Just yank the 3400 intakes, you'll have less work. With them you will need the TB and a WOT EGR adapter.I can tell you how to swap throttle shafts in the TB. With the 3500 upper you are going to have to move the FPR back.
The power is close(no tune or 19lbs injectors) and it shifts the band up to the higher RPM(no more gasping for air up there). Also it's better to tap the lower for your screw in type of coolant by pass connection.

3500 uppers tend to run much leaner on some cylinders, so you are better off with the 3400 or big port 3100.

[robertisaar]

i must have been looking at older info, when the 3500 UIM was assumed to be the best stock UIM available...

as for EGR..... rather than using an adapter, it looks like I could just patch the code to run the linear EGR instead. I've always been kind of curious to see how well they work and I have one sitting in my box of forgotten projects... all 3 EGR outputs used by the P66 V6 PCM are PWM capable, so I could drive it off of any one of those and end up with 2 spare PWM outputs. looks like there may be an input available on the E-side for tracking pintle position as well, but i'll have to do some digging to confirm.

damn..... I don't know what I want to do, this project has already taken far longer than I was expecting.

Jon, pending what I hear from the local yards on pricing, expect a PM from me on Monday, even if I do pull a large-port set, a small-port LIM for the cost of shipping is tough to beat.

[Purple pit]

I was talking about an adapter plate(sorry), the EGR mounting changed. That way you can use your stock EGR. Jon has gone back to the 3400 upper for many reasons by the way. If you don't trust me then ask him why. Just trying to help you out.

You are going to like the big ports, but there is a feeling of loss in the low end power(which there is). If stock low end power is what you like or need then go with the small ports. The big ports make use of the stock cam's upper end power, something the small ports don't do. I think you have a good FDR so the loss of low end will not be noticed as much. I can tell you that at low throttle range I miss the small ports. When the throttle is opened more than that I don't miss them at all. Use to hate that drop off in the higher RPM, that is by far gone. Feels like the big ports should have been on there in the first place.
Hell why not get both? Pick the one you like best!