This weekend I finally got around to starting my adjustable fuel pressure regulator mod on one of my spare FPR's. Drilled out the old bolt and tapped the spring cup to 1/4-28 like the thread said, then went looking for a bolt to use. That's where the trouble began. I now have 3 different bolts, none of which are quite right. My question is where do I find a flat headed 1/4-28 bolt with an recessed allen head. I have a bolt that is very close that is used in furniture, but isn't threaded the entire length and doesn't come in 1/4-28. The other 2 are 1/4-28 but one is a cap screw which has way too tall a head, and a flat headed bolt that is actually rounded and causes the spring cap to move around too much. Another question is about the length. The directions state a 3/4 inch bolt, but that seems to be too long, it sticks above the housing and I am concerned about it hitting the diaphragm.

 

I did not have to tap anything on mine....I made the bolt (stud, thing) that was in it turnable by cutting a slot across the face of it..My small craftsman screwdriver works perfectly to adjust it, even on the vehicle...Just need to put a gauge on now, so I know what I am doing...good luck...Tom

 

My local ACE Hardware carries those bolts. If you can't find one let me know and I can send you one. I have several

 

I am not sure exactly which bolt I am looking for. That seems to be the problem.


Is this what I need? And how far above the housing should the bolt stick when installed? Also, with the stock spring, on average what pressures can I expect.

[IMG]file:///C:/Users/Jim/AppData/Local/Temp/moz-screenshot.png[/IMG]

 

Stock spring and stock pump wont get much above 15-16psi. That is the exact bolt that you need. The bolt should be below the housing mounting surface because if it's above or level to the mounting surface then the bolt will hit the bottom of the diaphragm.

I modify the units a little different, but use the same style bolt. I remove the bottom tab both inside and outside the cover. This leaves a larger hole. I then take an appropriate size washer and place it in the bottom of the cover and seal it with a retaining compound. This will allow the bolt to be almost flush with the bottom of the cover and then the 3/4" bolt height wont hit the bottom of the diaphragm.

I may take some pictures in the near future.

 

Wow, I wish that info was included in the link at tbiparts.com A picture of the bolt in that write-up would be a big help for future reference by people like myself. Also I like the idea of modifying the can. I can see how to remove the outside part, do you drill the inside one out? and do you attach the washer to the outside of the can or internally? I would thing internally, because then it really can't go anywhere, but finding the correct size washer might be a problem. Thank you so much for your responses. I will probably get a new spring from tbiparts before i install everything. I am upgrading to ep377 pumps and have the passenger side tank one now. I am modifying these parts in anticipation of an eventual engine rebuild with the need for more fuel, and my calcs call for running 454 injectors at ~18 #'s to support the hp numbers.

 

The link I have on my site is the one you are referring to and Vader posted that back in 2001. I am tbiparts.com lol

It was hard finding the correct size washer, but I ordered a bunch and do have them if you need one.

 

Thanks, I will keep that in mind, I am going to town today to get bolts ( I made my own 1" TBI spacer so need longer bolts for the TB also. I have the 454 injector spider gasket which is thicker than the 350 one to install also.). Now to find the correct size salad bowl LOL And yes I was aware that you are tbiparts, which is why I brought it up