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Converting a B21FT intake manifold to a B23/B230 intake manifold
By: Justin Hinkley

This procedure is often performed, but not often talked about in detail. Some people have the conversion on their websites (Stu Spencer for example); but even then the details can be sketchy, not in-depth enough, or stray too far from a truly OE appearance for some. Hopefully this will clear up any confusion, and lead to even more finely tuned redblock Volvos staying on the roads where they belong.

Anytime you work on your car's fuel system or electrical system it is recommended to disconnect the battery and relieve the fuel system's pressure.

DISCLAIMER: As always, any modification you choose to do on your car is your choice. I hold no liability to anything you do to your vehicle.

Step 1: Gathering all of the parts.

This seems to be the most confusing part of the whole ordeal, as some parts can be intimidating to try and find if you're not familiar with this. It was a learning process for me, even with the other published guides. I will list what was needed for my particular conversion, and where I obtained the parts. Prices can & will vary. My overall cost and parts sources are simply an example.

Junkyard/Parts cars:

  • '93 B230 intake manifold from '93 940 ($25 from local Pick-n-Pull)
  • B230 intake manifold support bracket (free from '85 240DL parts car)
  • Bosch #501 idle air motor (free from '85 740Ti parts car)
  • B230 throttle body (free from '85 740Ti parts car)
  • B230FT cold-side intercooler piping (free from '85 740Ti parts car)
  • B230 throttle cable (free from '85 240DL parts car)
  • B230 TPS pigtail (free from '85 240DL parts car)
  • B230 throttle spool and linkage brackets (free from '85 240DL parts car)
  • B230FT idle air motor hoses (free from '85 740Ti parts car)
  • (2) Intake manifold studs, nuts and washers (free from '85 240DL parts car)

NEW parts:

  • Microswitch for TPS (Philmore, p/n #30-2501, found at Fry's Electronics - $1.69)
  • Intake manifold gasket (Elring, p/n #1378879, found at FCP Groton - $3.50)
  • Throttle body gasket (Elring, p/n #1271488, found at FCP Groton - $0.75)
  • (4) 9/16” Freeze plugs (Doorman, p/n #555-092, found at AutoZone - $1.00 each)
  • Throttle body idle screw gasket (Elring, p/n #463766, found at FCP Groton - $0.75)
  • Idle adjustment screw and TPS O-rings (Doorman, p/n #799-450, found at AutoZone - $5.00 – This is a 172 piece “Valve Pack” Metric O-ring assortment)
  • Vacuum lines (Bulk, found at AutoZone - $1.00/per foot)

Also, you'll need some Red Loctite, Solder, BrakeKleen or other cleaner, some form of epoxy sealant or RTV, heatshrink tubing, some rags, and a few hours of your time to go from this:

to this:

Step 2: Preparing your parts.

Clean, Clean. CLEAN! Take the time to clean your parts! I'm not saying that you need to go so far as to take your new-to-you intake manifold down to the local machine shop and have it hot-tanked, but why install grungy parts? Take an old toothbrush or maybe some pipe cleaners, some Simple Green or whatever you prefer, and scrub those parts inside and out until they shine. Media blasting also works well. This is also a good time to take your Dremel or Die Grinder and gasket match the intake ports and any other porting you want to do if you so desire.

Starting with the B23/B230 intake manifold, the red Loctite, and your 9/16” freezeplugs, let's plug those EFI injector ports in the intake manifold. A coating of the red Loctite around the sides of the freezeplugs will do nicely, then set them into place and use a ¼” drive socket that fits inside the cup of the plug (or female end of a ¼” drive extension), and take your trusty hammer and seat them all of the way into the bottom of the injector port. Don't hammer on them too hard or you run the risk of cracking/breaking the manifold. Make sure they seat evenly, otherwise they will be prone to blow out under boost. See PIC here:

Now for the fun part – the TPS. The K-jet system on the B21FT uses a large, usually white in color microswitch, where as the later B230 (LH) throttle body mounted TPS uses a smaller, usually white in color microswitch. This procedure simply allows you to retain the stock B230 throttle body and not worry about adapting the stock B21FT throttle body in this conversion. Take the TPS off of the B230 throttle body and gather up that new microswitch. Don't forget your trusty soldering iron and solder, some epoxy sealant and your O-ring assortment. You'll need to separate the two halves of the TPS housing. This takes a little work, and some patience. Bosch found it necessary to seal the two halves together to keep there from being any vacuum/boost leaks. I concur with Bosch's feelings towards this, so when I was done I used some two part epoxy sealant to reseal the two halves back together.

As you can see in this PIC here,

the OEM microswitch only has 2 posts (supposedly some have all 3 – I have yet to find one), and for this job you'll need that third terminal as shown on the black in color replacement microswitch. This is simply for the K-jet system on the B21FT. It requires a Normally Closed (NC) signal at idle, and the later LH systems used a Normally Open (NO) signal. The OE microswitch in the TPS housing is numbered, and from left to right reads: 2, 3, 1. the replacement microswitch reads from left to right: NC, NO, C.

If you miraculously find one of these TPS switches that have the 3 terminal microswitch, then your job just got easier. Simply take your soldering iron and disconnect the #3 terminal (middle terminal) from the OE microswitch. Now, solder the #2 (left terminal) to the post in the TPS housing that the #3 terminal was just soldered to. Congrats, you have just converted the TPS from NO to NC.

If you have to swap out the microswitch for the replacement 3 terminal microswitch; here's the procedure for you. Take your soldering iron and disconnect both terminals on the OE microswitch. Now, take a small screwdriver and gently pry upwards from underneath the microswitch. That should pop it out from the housing. If you are lucky, you didn't break off the 2 small plastic mounting posts in the TPS housing that the microswitch mounts onto. Now, before you drop the new 3 terminal microswitch into the housing, you'll have to remove the small lever that's mounted to the top of it, above the button. Compare the OE microswitch to the replacement in the PIC above and you'll see what I'm talking about. That lever simply pulls out of the housing, or you can cut it off. Either way, it has to go. If you leave it on, the switch will be activated way too soon when the throttle body closes, and you will not have enough adjustment to compensate for it. Once it's gone, you have one more small mod to make. The middle terminal (NO) on the replacement microswitch isn't used. You can either bend it over out of the way, cut it off or leave it be. Once done, you can drop the new replacement microswitch into the TPS housing. Make sure you keep the orientation correct so that the button is located on the right side of the TPS. Again, review the PIC above for clarification. A drop of Testers model glue (or any epoxy, Super Glue, etc) on each of the posts will keep it secure. Now you're ready for soldering. The far right terminal in the TPS housing gets soldered to the far right terminal on the microswitch (terminal C on the new microswitch, #1 terminal on the OE), as it was from the OE. Again, the middle terminal in the TPS, like the replacement microswitch, is unused for this conversion. The left terminal (on the microswitch side) of the TPS housing is soldered to the left (NC) terminal on the replacement microswitch (terminal #2 on the OE). Congrats, you have just converted the TPS from NO to NC.

Now that the TPS has been converted from NO to NC, the two halves can be fitted back together and sealed with some two-part epoxy, RTV, or something along those lines. They have to be resealed otherwise you WILL have vacuum/boost leaks. Also, don't forget to replace the O-ring on the back of the TPS before you reattach it to the throttle body to prevent any vacuum/boost leaks from happening there.

With the hard parts done, it's all basic maintenance from this point on in preparation. Replace the gasket and O-ring on the idle adjustment screw and plate on the throttle body, and refit to the intake manifold with a new throttle body gasket. Mount the throttle linkage and spool brackets to the intake manifold. Adjust the linkage from the throttle cable spool to the throttle body shaft. Adjust the TPS.

Let's get that TPS pigtail handled. Yours may have different color coding, but the one I grabbed happened to have the proper color coding that matched the OE B21FT colors and positions (black and yellow wires, terminals #18 and #2). Essentially, there are two ways to go about this: Cutting the female spade terminals off of the B21FT engine harness and crimping/soldering the pigtail into the harness, or: crimping/soldering male spade terminals to the wiring on the leads on the TPS connector pigtail so that it's "plug-n-play". The first option works best if you have no problems with modifying your engine harness. If you are wary of cutting up your new $300 engine harness, then the second option is better for you. Either way, if yours has the matching color coding (black and yellow wires), then choose your method and go for it. If not, then attach the yellow wire from the B21FT harness to the right terminal (#2 on the TPS), and the black wire from the B21FT harness to the middle terminal (#18 on the TPS). The left terminal (#3 on the TPS) is unused for this, but would be useful if you were to use the wide open throttle (WOT) switch in the TPS for something like a 5th injector, intercooler sprayer, etc.

Ok. At this point, you've taken care of prepping the manifold, the TPS, and the wiring harness pigtail/adapter. The hardest parts are done.

Step 3: Removal of the B21FT intake and prepping for the B23/B230 intake.

This is merely touching on some of the finer points to look out for & deal with (or messier points depending on how you look at it). You should at the very least be familiar with the removal and installation of the B21FT intake manifold to take on this job. If not, please refer to the Volvo “green” manual, Haynes, Mitchell, Bentley, Alldata, Chilton or other service manuals for guidance in this.

- Once the B21FT intake manifold is out:

Make sure you remove the manifold support bracket that attaches from the intake manifold to the motor mount brackets. It isn't being reused as the B23/B230 style intake has its own specific bracket.

Install the two intake manifold mounting studs in the cylinder head where the two long center mounting bolts were previously used to retain the B21FT intake manifold.

Remove the B21FT cold-side intercooler piping. It is being replaced by the B230FT cold-side piping, so it won't be reused. Also, take note that the vacuum hose (signal hose) for the OE boost controller or Turbo + kit, or aftermarket MBC or EBC will need to be rerouted to the B23/B230 intake after installation, as the B230FT cold-side intercooler piping does not have any provisions for this vacuum line.

Swap out the B21FT throttle cable for the B23/B230 cable. There are 2 screws that attach it to the firewall where it passes through into the passenger compartment. From there, under the dash you'll find a small black plastic shroud that covers the top of the accelerator pedal. Three screws hold it to the firewall. Once the shroud is out of the way, a small cotter pin retains the mounting pin at the throttle cable to accelerator pedal assembly. Remove the cotter pin, slide out the mounting pin, and remove the throttle cable by feeding it from the passenger compartment through the firewall into the engine bay. Installation of the B23/B230 throttle cable is the reverse of removal.

Now is a great time to go through and perform any maintenance to this side of the engine. Remove any remaining intake manifold gasket material from the cylinder head. You definitely want a nice clean, smooth mounting surface for your new intake manifold. Clean out the flametrap and oil separator, replace any CPR and thermo switch vacuum hoses, clean off the block, change the heater hoses, reseal the K-jet injectors, replace the engine harness , etc…

The fuel lines to the CPR can become a questionable item to deal with if you're not prepared. Two basic solutions you have are to: disconnect them and swing them out of the way until the B230 intake is installed, or cut the aluminum casting out of the way on the intake manifold between the #1 and #2 cylinder runners. Obviously, the former is the solution to go with. Unbolt those lines and lay them gently out of the way. Keep track of the copper line washers if you don't have any replacements handy. FYI - there are two washers and one banjo type bolt for each fuel line, just like the cold start injector (CSI). I always recommend replacing the copper washers for the fuel lines. Not doing so is done at your own risk. I take no liability in your actions!!!

Step 4: Installing the B23/B230 intake manifold.

Again, this is merely touching on the finer points of this conversion; since by now you should have fairly intimate knowledge of how to R&R the intake manifold.

After you have a new gasket in place and the intake manifold installed, feed the CPR fuel lines down between the #1 and #2 cylinder runners on the intake manifold and reattach them. I always recommend replacing the copper washers for the fuel lines. Not doing so is done at your own risk. I take no liability in your actions!!!

The cold start injector (CSI). This is another place where it's a matter of preference. The B23/B230 intake manifolds have two possible mounting locations for the CSI. Usually they have the lower CSI mount drilled & tapped, and had a blockoff plate installed, with the upper port either not machined, or machined for the EGR/Puls-Air system, resulting in the bolt spacing to be a bit off. I chose a later model B230 intake manifold that had the lower CSI port not machined, and the upper port machined for the EGR/Puls-Air tube. This allowed me to keep the CSI on the topside of the intake manifold, and keeping any new bends necessary to the fuel supply pipe for the CSI to a minimum. It did, however, cause me to use a flat gasket instead of the O-ring design like OE intended, and also forced me to notch out one of the mounting ears on the CSI to compensate for the wider bolt pattern of the EGR/Puls-Air tube. A Dremel with a cut-off wheel made it quick work. See PICS here for a better idea:

Depending on which mounting method you chose, you'll most likely need to reroute the CSI fuel supply line. BE CAREFUL! Take your time, be patient. Leave it to someone with experience in this area if you are not familiar or comfortable doing it yourself.

The idle air motor and intake manifold support bracket. This is where it can become a bit tricky. On an LH car, there is no CPR, so where the idle air motor mounts is a non-issue because it mounts on the manifold support bracket. However, because it mounts on the manifold support bracket, on a K-jet equipped car, the CPR is in the way. Stu Spencer's method was to modify a B21F idle air motor bracket and B21FT idle speed motor hoses. I chose a much simpler, and OE appearing route. I used the B23/B230 support bracket and the stock idle air motor mount on it, and to deal with the interference between the CPR and the idle speed motor, I used a small, ½” spacer on the upper mounting bolt where the bracket attaches to the intake manifold. See PIC here for a shot of the spacer:

…and a shot of the clearance between the CPR and the idle air motor afterwards. “Just enough” – about a 1/16”

At that time I also chose to 'upgrade' to the later style Bosch #501 idle air motor from my original #520 unit. The #501 is slightly smaller overall, but is otherwise a direct plug-in for this conversion. (The B21FT came with either the #500 or #520 idle air motor)

Step 5: Final assembly & clean-up

The final stages for this conversion include installing the B230FT cold-side IC piping and idle air motor hoses, connect the vacuum hoses, the throttle cable, reconnecting the TPS, CSI and idle air motor harness connections, the flame trap, and anything else that was disconnected or removed during this conversion process. It's all fairly self-explanatory, just remember that the Evap canister vacuum lines connect to the throttle body, just as they did on the B21FT setup. Don't forget to re-route the signal line for the boost switch on the passenger fenderwell to the intake manifold, since the B230FT cold-side IC piping has no provision for it like the B21FT cold-side IC piping did.

Reconnect the battery. Start the vehicle and check for fuel and vacuum leaks. Check and adjust the timing. Adjust the base idle speed if necessary. Take your 240Ti for a spin, enjoy the rewards of your efforts. Afterwards, bring it back and double check everything.

Special note for those with P/S and A/C:

Because the power steering pump is rocked so far away from the motor it interferes with the 700 series cold-side IC piping. (I believe the 83-84 700 series piping 'bends' around the PS pump because it had the B23 engine. This piping should be able to be used without much modification at all). I used 85+ piping. To get the PS pump out of the way (rotate towards the motor), purchase a shorter belt, I recommend the Goodyear 17415 (41.5" long). This belt may also be listed as 13AV1055 (13x1055mm).
This P/S 'special note' was taken from Stu Spencer's B230 conversion article, found HERE . Because the vehicle I based this write-up off of no longer has A/C, I did not have to deal with modifying the P/S in any way. Thank you Stu!



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