How To: Port Match the Intake for the 240SX TB Installation

WARNING: Do NOT port intake while it is mounted to the engine!

Applications:
L28 intake in the Datsun 280Z, 280ZX, 280ZXT
L24E intake in the 81-84 Nissan Maxima

Step 1

Prepare a working surface.  Remove the intake from engine and clean the intake as necessary.

Step 2

Hang the new throttle body spacer gasket on intake as shown with throttle body mount screws.  It will be used as a stencil in the next step.

Step 3

Make sure gasket is centered on the four bolt holes, and use a permanent marker to mark its opening.

Step 4

Remove gasket and make sure marks are easily visible.

Step 5

Take the time to observe the shape of the intake.  The intake tapers as it approaches the original throttle body opening.

Be cautious when porting this opening.  It cannot be cut perpendicular to the front face in all locations because of the risk of cutting through the manifold.

It is better to cut more later than to cut through it now.

Step 6

Prepare to port the intake.

Have:
Safety glasses
Rag
Cutting tool
Cutting lubricant (motor oil works fine)
Die grinder (an electric drill will work too)

Step 7

Stuff the rag just inside the opening to prevent chips from getting deep in the manifold.  This just makes the cleaning process easier.

Put some oil on the surface that is going to be cut.  Be sure to lubricate it frequently.  Doing so will extend the life of your tool and shorten the time it takes to cut.

Step 8

Port the intake.  It will take some time to cut away all the material.  Cut slowly, and only cut away what was previously marked for cutting.

Make all the transitions as smooth as possible.

Step 9

Check to make sure all the markings were met and that all the transitions are smooth.

Notice: the left side is the only side that was cut straight through.  All other sides have a bump due to the intakes taper.

Step 10

Hang the new throttle body gasket again to make sure all edges line up correctly with it.

If they do not match, re-mark the opening, REMOVE the gasket, and repeat cutting process until they do.

Step 11

Remove the gasket, pull out the rag, and clean the intake thoroughly.  Stray metal chips can severely damage an engine if not cleaned out.

Note: put mouse over this picture to see original vs. modified bore.