3100 to 3400 hybrid

[viper15230]

I was wondering what all I would need to do to swap some parts on my 3100. To use 3400 or even the newer 3100 manifolds do I need to swap the heads too? Or can I just throw the 3400 lower and upper intake manifolds on the 3100 heads?

[IsaacHayes]

You can, but might have to grind the lower intake for clearing your rockers if you don't have roller fulcrum. What year is your car? 94-95 don't have roller fulcrum. And then there is EGR adapter, and coolant pipe attachment.. What year car?

[bszopi]

The ports from the lower manifold to the heads don't line up exactly, so you won't be getting the best airflow. But several people (including me for alittle while) have run it that way without any adverse effects. So if you are on a budget, go for it. If you are looking for more performance, then getting the heads would be beneficial.

[viper15230]

well the motor is out of a 95 grand am, but It is a rebuilt one so Im not exactly sure if it has to be a 95 or not? Any way of telling?

[IsaacHayes]

If you can see the rocker arms, and see that they are roller fulcrum, then no grinding needed. If they aren't, then you need to grind the LIM for clearance.

Pulling a valve cover to look will show you. You *might* be able to see through the oil fill cap hole too.

[Crazy K]

having done this here's what I know.

The ports from the lower manifold to the heads don't line up exactly, so you won't be getting the best airflow. But several people (including me for alittle while) have run it that way without any adverse effects. So if you are on a budget, go for it. If you are looking for more performance, then getting the heads would be beneficial.

heads:
the intake ports on the head are nearly identical. they have the SAME intake opening (on the ones I compared). the only intake side difference is GM relocated the peg hole for the intake gaskets above the center intake hole on the head. (I have drilled a new hole on heads to accept the peg with no adverse effect)

If you can see the rocker arms, and see that they are roller fulcrum, then no grinding needed. If they aren't, then you need to grind the LIM for clearance.

WAIT! if you have a later production 95 engine, You may be able to covert to roller rockers. You need to determine is your heads are slotted beneath the rocker pedestals. if they are, grab some roller rockers from a donor and discard the original rockers. (or sell them to someone who wants them for a 3.1 MPFI upgrade)

[IsaacHayes]

Ah yes forgot about the notches. If your heads have them you can convert to the roller rockers.

Welcome to the board Crazy K. Stay awhile.