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*                  HOMEMADE ADJUSTABLE REGULATOR                   *


*                               by                                 *


*                   J. D. Carballo, Houston, TX                    *


*                                                                  *


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Well, I got tired of looking at my old stock "233" fuel pressure regulator


lying in the bottom of the tool box so I decided to try and make it


adjustable or destroy it!.  I have never seen how the aftermarket folks make


them, but figured that I would try and cobble up one myself.  I really don't


need one and am running fine with the 3 bar "237" and  factory fuel pump.


 Anyway, the experiment seems to be a success and I have converted several


regulators to the adjustable type for a grand total of $0.32 each!   If you


still have your old "233" lying around you may want to give this a try.  It


only takes about 5 or 10 minutes.





Tools:  8-32 thread tap


           #29 Drill bit (or 9/64" will do)


           5/64 drill bit 


Parts:  Roll pin 1/8"dia x 5/8" long


           8-32 allen set screw 5/16" long





1) Place a tape marker on the #29 (or 9/64") drill bit exactly 1" from the


tip.   Now drill out the vacuum inlet to this 1" depth.  Do not go any deeper


or you will be getting close to the diaphram (it is at approx. 1 1/4" in.).


  Notice that you will really only be drilling at the  very tip of the inlet,


and then just checking for stray metal at the point where the inlet joins the


body.  The inlet tube itself is just slightly larger than the #29 bit.





2) Now run the tap through the inlet tube to a depth of 1".  Be gentle and


use plenty of WD-40 or whatever.   You want to take it easy because the tube


is only crimped to the body and excessive force may cause the tube to spin


free.   To be safe you can hold the tube with a pair of pliers while doing


the tapping.  Flush out the hole with WD-40 or carb cleaner after cutting the


threads.





3) Jamb two nuts together on the allen set screw and then clamp the whole


thing in a vice with the bottom of the set screw facing up.  Using the 5/64"


 bit drill out the set screw.  Be careful coming out the other side.  The bit


should cleanly fit through the allen slot without damaging it.  Note that set


screws have a  dimple in the center of the bottom which makes drilling them


out a breeze.





4) Drop the roll pin into threaded vacuum inlet.  It should slide down to the


diaphram.  Before dropping it you can check for gauge with a drill bit to be


sure that none of the flashing from the tube-to-body crimp got in the way


during thread cutting.  Using a roll pin provides a good conduit for


vacuum/pressure since  it is both hollow and has a slot running down its


length.





5) Screw in the set screw until it just contacts the roll pin and note where


it is located in the tube.   Remove the set screw.





6) Now *gently*,  using a small pair of vice grips, *barely* crimp the tube


at the center of where the set screw was located.    Try the set screw.  It


should have just enough resistance to firmly keep it in place.  If it is


still too loose, remove the screw, give the vice grip adjuster knob about 1/4


turn and do it again.  Continue 'til it's just right.   If you should go too


far, just run the tap through it again.  There is plenty of metal.








Just install the regulator and go.  With the set screw backed out you are at


stock pressure.  By screwing it in to apply *gentle* pressure on the diaphram


you can up the base level to 60psi and beyond (at idle, no vacuum).