Intake gaskets and 56mm TB

[Coogles]

Hey all,

I don't believe I've ever introduced myself, but I am currently dd'ing a 1996 Buick Skylark Gran Sport. I bought it in December from an older gentleman, the original owner, who had only put 63k miles on it. It's red on tan leather and is in fantastic condition aside from some curb rash on one of the wheels and some small paint nicks. Some new brakes, control arm bushings and a couple simple maintenance items later and I've got a great-running car, but I'm looking to be proactive and get those problem-solver gaskets in there before my motor starts developing the inevitable coolant leak. I'm sending out this first oil change for analysis, so we'll see what kind of sodium (coolant) content they find.

Anyway, does anyone know where I might find a writeup for the procudure? I know picking up a factory service manual would probably be my best bet, but it always helps to see user pictures and advice about how to do these kinds of things.

As for the 56mm throttle body, will that bolt right onto my small-port inatkes? It seems weird to me that GM would use a 52mm TB on an intake with a 56mm or larger opening, but they do it on the L36 and L67, too, so I guess I shouldn't be too surprised. I don't plan on doing any real mods (that's what the GTP is for - don't hate me!), but since the 56mm is so cheap I thought I might as well go for it anyway.

Thanks all!

[IsaacHayes]

Your manifold is 52mm, and will need to be ported to the 56mm.

Unless you swap to the 3400 or 2000+ 3100 intake manifolds which are big port runners as well in addition to being 56mm.

[Coogles]

The local yard has a bunch of 2000 and newer 3100's on site, so depending on what kind of prices I can get I might go ahead with the large-port swap.

Anyone want to help with a parts list?

Upper Intake
Lower Intake
Throttle Body
Coolant return line from the heater core
EGR Valve
And gaskets, of course.

Is there anything else?

I don't think I'm going to port the intakes or go with one of the billet TB's, so should I assume that the stock PCM will be able to adjust to these (relatively) minor mods? I really don't want to get too involved with this whole swap if I decide to go for it.

Thanks for helping the L67 guy.

[SappySE107]

Stock small port has a 55.5 mm opening, so that can take a 56mm without any real issues. If you swap manifolds, I have a 3100 large port 99 upper that will use the same EGR that your small port manifold uses. Its "ported" already, meaning i bought it "ported". Its not gasket matched or to my standards, but its polished up and better than stock. $50 plus shipping and its yours if you want it. Just need a lower, and the metal LIM gasket set (or buy the manifold gasket set from my store and get the high temp oil pump drive o ring to avoid an oil leak in its future). Otherwise, any 96-99 3400 upper will work as a drop on with a large port lower intake. Make sure you use a metal gasket kit to rid yourself of the plastic gaskets.

Stock tune is fine with large port and 56mm TB as long as you use your stock injectors.

[Coogles]

Depending on what prices I can get from the yard, I'll probably stick with the 2000+ pieces.

What about rockers bolts? Since the pushrods have to be removed to get the lower intake gaskets out, thus forcing the rockers to be retorqued during reassembly, don't we need to replace the rocker bolts as well?

Are they not TTY?

[bszopi]

No, rocker bolts are not TTY.

[IsaacHayes]

If you don't want to adapt the new style coolant return line, you can use a 3/4" NPT tap for the LIM and use your old style stuff.

And yeah for 2000+ UIM you'll need the 2000+ EGR and EGR tube and it will work with your computer just fine. Or if you find a 1996-1999 3400 UIM then you can use your old style EGR but the older big port upper intakes don't flow as well as the 2000+ ones.

Verify you have roller rockers (you can probably tell by just looking through the oil fill cap. Some 96 heads did not get them, but should have notches for them. If you don't have the roller fulcrum(not tip) rockers you'll need to grab those and swap those over (any 3400/3100 96ish-2003. I think in 03 they went to 8mm instead of 10mm stud). As if you don't have roller rockers the rockers will hit the lower intake unless you grind the lower intake (not fun).

Rocker bolts are not torque-to-yield, it's not much torque at all so re-using them is no problem. You can re-use your intake bolts too as long as you clean the threads off and put on some blue thread locker. I recommend the metal intake manifold gaskets not the plastic kind. dorman and felpro make metal ones now.

Computer will tolerate the mods just fine.

My computer is un-tuneable and while I could get more power if I could tune it drives just fine with 3400 lower intake, 3500 upper intake, and a 65mm TB, with a nice power increase.

DONT mix up the order of the pushrods, or you'll be in big trouble. they are different length.

Oh yeah the brown oil pump oring from the dealer is a good idea while youre there for the oil pump drive shaft.

For what it's worth my 3100 small port was not 55.5mm on the TB opening. It was way small with a 56mm TB paired up to it. It was way more than .25mm lip. But mine is a 94 casting.