Intake gasket leak, removing heads, porting heads and manifolds

[Filter]

This thread is gonna cover alot of different problems and performance upgrades cause I wanna address a bunch of things at once.

So my intake manifold gaskets are leaking AGAIN. When I replaced them the first time, it was with the orignal design gaskets. So part 1 of my thread begins

1. I heard that GM changed their gasket design to a 2 gasket design. Is this true? If not, what are the changes?

Now the fun part. When I fixed this the first time, I was more concerned with just fixing the leak. This time, I wanna do that AND make some power. I have the 62 mm TB from FDP, but it's not installed. I was gonna do it, but I'll wait so I can do it all at once. I'm gonna match the upper intake to the TB, but am not sure if I wanna do the rest. Now part 2.

2. I've heard that porting the upper and lower intake manifolds is a waste of time because they flow well enough stock. Is this true?

When I did the gasket the first time, I noticed that it was basically not much more work to get the heads off cause I was in so deep. Now part 3.

3. After removing the lower intake manifold, what else has to be done to get the heads off?

Is it's not much work, might as well take the heads off and do the head gaskets. After all, they'll go someday so might as well start fresh. Now with them off, part 4.

4. I've heard that the only thing worth porting and polishing is the heads and when you do, the car will flow like mad. Is this true?

Seems to me that once this is all done, I'd have a nice setup. 62 mm TB with matching upper intake manifold, ported and polished heads, and new gaskets all around. All I'd need are headers and the engine should pull like mad. Please let me know.

[AaronGTR]

Gm did have problems with the lower intake manifold gasket leaking. They designed a new gasket (it's one piece) and gave new install procedure and torque specs to solve the problem. Not all cars have the problem (mine's not leaking yet) but it's a good thing to replace if you're doing engine work anyway. I'll be replacing mine when I put my RSM ported heads on soon. As far as the head gaskets go, there should be nothing wrong with them. They tend not to go bad until you get into the very high milage. Again though, if you're going to take the heads off and get them ported, get new gaskets anyway. I think porting the heads will give you a bigger gain than the intake manifolds. The intake manifolds wouldn't give much of a gain, but on an NA engine you need every little bit of power. At least match the TB to the UIM. If you do get the whole intake mani ported, have them basically smooth the surface, but not enlarge the runner too much. This will smooth the air flow without decreasing the air velocity and losing torque.

[Dr_Kyle]

Heads would be a good idea since you're already in that far. I'd also recommend you gasket match everything. There's a pretty decent gain to be had from this, especially where the heads meet the lower manifold. You're gonna have a monster when you're done with all this! Add headers and you'll have a mid-14 second car.

[jaketuff]

Manifold porting aside from near the TB on the UIM will give little to no gain. Certainly nothing noticeable on the track. A mere gasket matching should be good enough (b/w UIM-LIM to make sure the flow is smooth, but I think most are smooth there factory from what many have said). CAI, 62MM TB, ported UIM gave 8HP at the wheels when Aleroboy dynoed them.;) That is 10 HP at the crank. So YES, heads will give a lot more...

(The TB/UIM really smooth out the power curve, while adding their power.)

JOUT