Should i bother porting?

[lilnbody]

replacing the LIM due to a crack in the T-Stat housing, my question is, should i bother porting the UIM and LIM when i'm not porting the heads? Should i only cleanup and gasket match the topside of the LIM to the UIM?

The engine is an '01 3100, LIM is from a '02 3400... which is in a '96 Grand Am. There's no cam, no head porting... just an intake and a shift kit is all that's done to it...

[IsaacHayes]

If you have it off and can port, why not? I ported my 3500 plenum and 3400 lower before I put it on. Just that much better transition of flow. I just did the top of the UIM of course since I didn't remove my heads. I gasket matched to the 3400 UIM gasket, and bell-mouthed the 3500 plenum.

[Mars]

It's kind of hard to explain, but I ported the hell out of my UIM and LIM.

What I did was cut the whole UIM gasket right in the center of the bead of red silicone, then, I matched up the manifolds themselves.

Not sure if that was overkill or not, but in some spots, I was cutting like 1/4" off the port. haha. I also then bellmouthed the inside of the 3500 plenum.

6 big holes in there now.

It helped out the top end I think, but this is with boost... If I was you, I'd port them as best as I could. With good cutting bits, it's pretty quick work.

[lilnbody]

I wasn't totally sold on what i will be gaining from it, if anything. I was going to take any flashing out around the lower part of the LIM anyways, but wasn't sure it was worth the time/effort to gasket match the upper half of it to the plenum.... the only thing left, that i wanna do, with the car is a bigger TB and a UDP if i can locate a used one this spring...

Mars- just looking at the gasket lineup on the IM, that's ALOT of work to cut that much away lol

If i was able to do a j/y turbo (turbo on the cheap) i'd do it, but the amount of work required and then having to have the computer flashed isn't worth the investment with gas at $4.00 a gallon for regular... tho it would be fun.

thanks for the advice, i'll get to work on it

[El_Diablo]

theres a FFP UDP in the for sale section right now

[IsaacHayes]

Mars yeah you could do that, and taper the 3400 LIM top port down from the big opening to give it more of a funnel shape. Have you looked at the 3500 UIM metal gasket? It's got huge opening, I wonder if your cut gasket is the same or less/more? Hmm.

If anything it's peace of mind so you're not thinking man I should of done that while it was off. I'll never take it off again... LOL FTW though the ports on my small port 3100 were nasty casting, like the ports on the top of the LIM were not even oval. It had all kinds of notches and odd shapes haha.

[IanSzgatti]

I replaced my LIM gaskets about three months ago and I did it without thinking twice... i dont even care that my ass dyno cant pick up the difference, I just had fun doing it... and for my broke ass, thats a good thing... one day though... muha ha ha ha ha!!!

[95Grand-Am]

Depending on the time you can give up the car, you could pull the heads your almost there anyways. Then you could do the job right.

[lilnbody]

I could pull the heads, but i'm not sure it'd be worth going through all that hassle... i'm a big guy and hate how cramped the area is.

And not only that, we just finished rebuilding the head on my wife's Neon- interference engines suck, and it's especially worse when the UDP is stuck on the crank lol.... and we don't have a heated garage to work in, working in the in-laws garage and they want it back before the snow starts flying aswell...

[ForcedFirebird]

Have you looked at the 3500 UIM metal gasket? It's got huge opening, I wonder if your cut gasket is the same or less/more? Hmm.

Here's a metal gasket on top of the red silicone/paper gasket, I think Mars' would be about the same as the metal ones...

[ezrollin]

Not much to be gain with more than a port /gasket match in most cases.

[SappySE107]

Quality goes a long way for porting manifolds or heads.

[el_roy1985]

Where can I obtain a set of metal UIM gaskets for the 3400? The parts store only has the plastic type. I'm porting my upper and lower intakes, so it would be nice if I could get a set.

[Z26-T]

I don't know if they make a metal UIM, but they make a metal LIM gasket... Just go into a parts store and ask for the 3400 felpro metal gaskets.

[IsaacHayes]

the metal is from a 3500. AFAIK you can't buy it separately from GM.