B23/B320 Manifold Conversion For B21FTi Motors page 2

B23/B230 Intake Manifold Conversion For B21FTi (Continued)
Rewire the TPS:

Remove the TPS from the throttle body
Open the TPS by gently lifting the tabs around the case. The case seems to be epoxied or sealed so it takes some work.
With the main plug pointing towards you, the idle switch is on the right and the wide open throttle (WOT) switch is on the left.
Unsolder/cut lead from #3 on Idle Switch and solder this lead to #2 so that the main plug terminal #18 is connected to Idle Switch #2. If your Idle Switch does not have terminal #2 you can go to an electronics store like Radio Shack and get a microswitch and wire to the N.O. side

This is what the TPS looks like with the cover off.

Terminal Connections in TPS BEFORE Modifications

Main Plug	Idle Switch	WOT Switch
18	1	1
2	3	Not Connected
3	Not Connected	2

Terminal Connections in TPS AFTER Modifications

Main Plug	Idle Switch	WOT Switch
18	1	1
2	2	Not Connected
3	Not Connected	2

Using a continuity tester, verify that all connections are good.
Close and reseal TPS. This is important because the TPS 'seals' the end of the butterfly valve shaft in the throttle body. A poor seal will result in intake air leaks.

Prep the Throttle Body (TB):

Clean throttle body with degreaser.
Replace gasket on throttle body shaft.
Replace gasket (O-ring) and reattach TPS
On the B21FT throttle body there is a small plate with a tube that the constant idle speed (CIS) tubing connects to. It is in the same position as the idle speed adjustment screw assembly on the B23/B230 TB. On the back of it there is a small post about 3/8" tall. Cut this post from plate so it can be transferred to the B23/B230 TB.
Remove idle speed adjustment screw assembly and replace with modified block off plate (use new gasket).

The idle speed adjustment assembly.

Mounting Bracket for Idle speed Motor:

Using the bracket from a B21F (normally aspirated) with the Constant Idle System, remove the 'rear' rubber mount (you won't need it).
'Flip' the bracket and attach the idle speed motor. You will need to rotate the motor in it's bracket so that the arrow points toward the manifold side connection and away from the pre butterfly connection.

Idle speed motor bracket before and after.

Assemble and Attach the Manifold:

Remove old manifold (duh) and label all wires and hoses. (This is a good time to clean out the oil trap, check all those sensors, and look at the wiring harness.) Plug holes in the head with rags to keep crap out of the motor.
Remove old throttle cable from car and replace with B23/B230 throttle cable. It is easiest to do it now.
Reassemble TB, and brackets onto manifold.
Adjust TPS on TB to 'click' just as the butterfly is opened.
Mount idle speed motor and bracket onto the manifold. The holes in the manifold are spaced a little closer than the bracket so you need to get both bolts started before tightening. I recommend using washers on the top and bottom of the rubber mounts.
Replace nipples (if you removed them). Using teflon tape helps seal the threads.
Install cold start injector where the old diamond shaped plate was. Either make a new gasket, modify a new block off plate gasket or get a big fat O-ring to plug the hold around the injector.
Route CIS hoses. Make sure the arrow points the right direction.

Editor's note: The routing of the CIS tubing will be dictated by your personal taste. If you don't like the routing of the tubes 'over' the manifold, you can either find pre bent rubber hoses from another car or machine out the blank spot by the vacuum connections on the TB and add a nipple like the B21FT TB. Whichever tubing you use, make sure it does not collapse under vacuum at idle or overrun.

Put 2 new manifold studs into the head.
Wire electrical plug and leads for throttle position switch (TPS). You need to connect to #18 and #2 on the main plug. Connect #18 to ground and #2 to the yellow wire.
Preliminarily mount manifold onto head using new gasket.
Attach manifold support rod to front two motor mount bolts and to the manifold. (some people don't like the look of the stock support bracket and have replaced it with a nice piece of 1/4" stainless steel bar stock from the #1 runner straight down to the block.)
Connect supply line to cold start injector. I basically straightened the line out, then put two 45 degree bends in it so it runs between #1 and #2 intake runners. Careful not to kink the line.

Supply line connected to cold start injector

Cold start supply line running between #1 and #2

Supply line routing for cold start injector

Plug in idle speed motor, TPS, cold start injector, and attach ground wires.
Torque everything and attach throttle cable(s).
Attach vacuum connections. The brake booster connection is now at the rear of the manifold just behind the TB. The TB connections are the same as the B21FT. There are a few 'extra' ports on the plenum section when you're all done.

Note: These pictures show the double spool and 'extra' bracket needed for if you have cruise control. Continue to page 3.....

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