Submitted by: Z28gen3

TBI AFPR
This is how to convert the stock regulator to an adjustable one.

Tools needed to do this are:

  • A bit no bigger than 1/4 as the hole is about this big.

  • Drill press is easier, but drill motor will do just fine.

  • T20 TORX bit, a set of TORX and Square bits is really cheap buy them you'll need them later. For other things

  • Dremel w/ cutoff disc(s) hacksaw will do the job also and possibly an injector pod gasket or gasket material and cut your own.
     

Disconnect negative battery cable.
     
Remove aircleaner get it out of the way.
     
To relieve system fuel pressure, remove the gas cap.
     
Disconnect injector pigtails and get them out of the way. Also, take the aircleaner stud and turn it so its not in the way.
    
Remove the (8) Torx screws on the top of the injector pod. Remember where the 3 longer screws were removed.
     
Remove the screws from the top of the injector pod and remove the injector pod roof. Some fuel will leak out try not to break the gasket or let any dirt mix with fuel and run into the engine. The fuel pressure regulator is attached to it.  its rather a dirty gold color.
 
The tab sticking out of the fuel pressure regulator cup. This is the range of adjustment. The higher the tab is the more compressed the spring is equaling more fuel pressure. 
     
Now you will have to disassemble the fuel pressure regulator. There are four torx screws holding the cup to the injector pod "roof." Evenly, loosen the screws while maintaining firm pressure on the cup. Because it holds a spring under some tension. Remove screws evenly while maintaining pressure. Once all 4 screws are removed, carefully lift away cup. The spring will release tension and you may set it aside along with the injector pod roof.

Okay here's the kit I purchased from AutoZone part # 97-724 made by GP SORENSEN price(34.99 plus tax). This is because the store I went to doesn't carry # 96-3031A. And plus I Live in Arizona), this particular kit includes everything including the diaphram, filters, enough gaskets to rebuild the entire TBI. * Fredless* also has a Part number 96-3031A   Go to Autozone and get a fuel injection repair kit, costs 6.49 or there about. Yes, the injectors just wiggle out...If they've sat in there for years, it'll take a little elbow grease to get it out.  The manual suggests that you use a round tool like a screw driver lay it on the gasket surface (fulcrum, leverage) and with another pry bar, pry up on the flanges on the injectors
 

A small platform with a tab that sticks out the side of the cup rides on a threaded shaft. The higher the platform in the cup the more compressed the spring and the more fuel pressure is achieved.
 
Now to make the threaded shaft movable and easily adjustable. You'll noticed the shaft does not move. Flip the Regulator over and take note of the pressed in cap in the hole on the bottom of the cup. This must be drilled out. Its pressed in there quite well, and is not easy just to pull out. Many people say you have to completely drill out the cup. That's partially true. I have 3 FPR that you only need to punch a 3/16" diameter hole in and push a pick in it. Thump it with a hammer and pry it out. For one, if you can get the cup to not spin as you drill it you can eliminate this step. I went to the J-Yard and picked up some regulators off the Caddys that where lying around.  Be careful so as to not exert too much pressure as it is possible to knock out the metal piece that is pressed into the cup on the bottom in which the cap sits.
 
Now that you have drilled out the cap, you will find that the screw and platform inside the cup are not only movable but removable from the cup. On some Regulators the screw will fall out you have the option of not drilling out the cap but that takes away from the adjustability of the Regulator. Turning the screw counter clockwise you raise the platform thus raising fuel pressure. Raising the platform to the maximum level will preclude you from making it adjustable. Thus you have maxed out the fuel pressure
     
Now if you have a Dremel with a cutoff disk this is easier. Cut a slot in the head of the screw so that a small flathead screwdriver can be used to turn the screw.
    
Reassemble with a slightly higher or lower fuel pressure setting depending on how lean/rich you're running. Turn the cup around so that the tab visible so that you can view the amount that the platform is raised. Optional, but since you have to remove the top to adjust the Regulator really what's the point.
 
  Put injector pod roof back on top of injector pod. Retorque the screws i believe the inch pounds are 10-22 inch lbs. Reverse the steps you took to remove the injector pod roof and replace the assembly and start your car.  Watch for leaks. If leak is present  tighten screws more. Not too much or you'll strip the threads. If its still persistent, you may need a gasket. If you have replaced the gasket and it still leaks, then I would suggest this: using a large flathead screwdriver (or something that fits on the top of the injector), and using a soft driving force like a deadblow hammer thump the injectors until they seat properly or if you can you may push them in by hand. You can use silicon gasket maker but if you don't use caution you will plug the injectors.
 
Ohh about the Caddy injectors that depends. A SBC 305 TBI is the same, unless they're cop injectors. 305 injectors flow 44lb/hr, 350 Injectors are 55lb/hr, 350 Cop injectors (Caprice TBI that were for cops) flow 65/lb hr and I think 454 TBI injectors flow 80lb/hr. TBI units are all the same from 4.3L to 5.7L, then when you get into BBC engines, they change to 2" bores. A 5.0L TBI is identical to a 5.7L tbi  Except the Injectors. 
 

 

 

Polishing & Porting the TBI.
Tools needed a HSS cutter for a dremel or a die grinder will work be careful as to not get to aggressive and cut more then you want off, because you can always take way material but not add it. I used a Floor Drill Press with 6-axis movement, was much easier but hand work will do just fine. Dremel part: # 194 HSS cutter, # 511 Finishing abrasive buff, or you can just buy a small kit and get some grinding wheels and cutoff disc's. Do not buy carbide tools, High Speed Steel tools will work just fine and will not load up as fast. Also a burr will work don't buy into a real aggressive cutter.

Cut the lips of the bores off take them to a flush fit on the TB, do not chamfer 45 Degree edges on the bore chamfering the edges may inhibit airflow and will not help to increase the flow either instead round the edges and polish them. i haven't ground down the locating stud hole yet i don't personally think it is a good idea its there for a reason, but if you see the need to eliminate it, do so at your own risk, the tab sticking up on the rear you can cut that off if you want, but i would definitely leave the 2 tabs on the front since the ring locates off them and this prevents spinning of the filter assembly, unless you have ditched the whole thing altogether, but since you don't need the full height of the tabs you might want to knock them down a bit.

Polishing the Unit start off with WET SANDING 180 grit and move to 240 progress to something finer until you reach 2000 grit yea its fine and loads up fast but if you take your time, do a nice job you will be pleased.  hand sanding is recommend since the power tools you cant control the amount of time its stationary a few seconds may mean the difference between smooth or deeply scratched.   sand the bores as well, but try to follow the grain of the metal, otherwise it will look 1/2assed.  

Cutting the Throttle shaft I ("Exdog") turned the throttle body upside down and used a cutting wheel on a dremel to take it down. I would have had better success with one of the composite wheels though. That hardened steel ate the ones I had up pretty quick. If you have a flex shaft for the dremel it would be easier too.  It is stressed that you be very careful when cutting the shaft you don't want to gouge the walls of the TB. If it is possible to remove the shaft this is better but you may not have that opportunity, so take you time, expect to use lots of grinding wheels as Exdog says it is very hard.


A Special Thanks go out to the following for helping me obtain information, parts, and allowing me to quote them and answering my questions about AFPR's and P & P.
MRR23
EXDOG
FREDLESS
FLATHIRDGEN