it's been awhile since i ran a setup with external regulator, but I believe i made a block off plate for to replace the original regulator then the return line from TBI to went to the inlet on the external regulator and then return line to the tank hooked up to the external regulator outlet. supply line stays the same. the popular regulator was an Aeromotive 13301. i have my one from 10 years ago thats been sitting in a box lol
Last edited by tayto; 11-02-2022 at 04:42 AM.
Wow those are pricey. I may just try to use the stock one in my project. So the regulator should go on the return, and you take the spring out and just put a plate on the regulator part of the TBi? Sounds easy enough, but I hope I don't need one, prices of everything seem to be higher than just last year.
No need to re-invent the wheel. But we can make it better
The "Small TBI injectors" are known as Multec bottom feed injectors. There were a number of applications that use this design injector, both TBI and PFI. Years ago the Delphi site provided a wealth of information for OE GM injectors. I spent a bunch of time collecting as much as I could. In addition, Holley sold aftermarket TBI systems that used injectors with similar external dimensions. There are some threads here on Gearhead-EFI that have injector information. You are correct about it being difficult to find flow information for the BBC Bottom Feed injectors.
http://www.gearhead-efi.com/Fuel-Inj...feed-injectors
Contains a small spreadsheet with Multec bottom feed injector information from GM vehicles and a separate listing with some old Holley injectors.
http://gearhead-efi.com/Fuel-Injecti...-Injector-Info
This thread has injector information for a number of different injector types, including the Multec bottom feed injectors. The Multec information is the same as in the previous thread, but I am including the thread as other folks may find it useful.
Injectors are generally selected using the estimated horsepower output of the engine rather than the displacement. If I were to install TBI on my stock 1936 Plymouth, I would use the 82 horsepower rating to select a single 44 lb/hr injector. Trying to match the displacement, 216 ci, to a TBI engine I might end up with a throttle body from a 3.1L TBI engine and a pair of 33 lbs/ hr injectors. That would be very challenging to tune.
What is the estimated hp produced by your 91 ci engine? A 75 hp engine using a single injector should have roughly 39 lbs/hr fuel delivery. The closest stock bottom feed injector in the list I have is from an 88 Lemans, 42 lbs/hr. That's a tough car to find and maybe a tough injector to find. An alternative might be Delco 217-340, rated 52 lbs/hr @ 29 psi. Lower fuel pressure to 17 psi and the injector flow drops to 39 lbs/hr. Another alternative might be locating an old 2.8/3.1 2 bbl throttle body and replacing the stock injectors with a pair of injectors from a 94-96 port fuel injected 2.2 Cavalier, 17 lbs/hr @ 43.5 psi. Increase fuel pressure to 60 psi and you have a pair of injectors delivering 19.8 lbs/hr each.
Injector calculator used is here: https://deatschwerks.com/pages/fuel-injector-calculator
The 2bbl TBI used on the 2.8 / 3.1l engines is a model 220. An adjustable regulator can be found here: https://marine-performance-parts.com...843505774.aspx
A stock cover can be modified fairly easily:
https://www.gmsquarebody.com/threads...gulator.23669/
I actually have a selection of higher pressure springs left over from years ago.
Does the cover of the model 700 TBI FPR have an adjustment screw? Is it possible to modify the cover to make the FPR adjustable?
yes discard the old regulator housing, spring and diaphragm. you will have to make a fuel resistant gasket or i guess you could modify the diaphram and use it. i believe I got my block off plate and gasket off a guy on ebay but this was 10 years ago now.
I knew there had to be some info on them somewhere, thanks for the wealth!Originally Posted by 1project2many
Stock ratings are between 92hp and 106hp.
IT will have a header and 2 1/4 in exhaust, and an unknown cylinder head purchased from ebay that came from a machine shop its OHC and I don't know what cam is in the head. I would say 110hp would probably be a safe estimate for injector selection? Stock redline is 7200rpm, I believe that also favors a larger injector for limited time to open at higher rpm.
That sounds pretty good, I like the idea of higher pressure
According to that 110hp NA needs 57 pph injector, and 90hp needs 47 pph
[/QUOTE] I haven't actually had my hands on it yet, I'm a couple thousand miles from home, trying to source everything I need for the project. The one I was able to find came from a 1990 cavalier 2.2
could you just leave the spring out and put it back together, with the housing?
No need to re-invent the wheel. But we can make it better
I have found as long as the pressure of the external regulator is higher than the tbi regulator you don’t have to do anything to the tbi reg. Just hook the return of the tbi to the inlet of the external reg and then to the tank. That has worked for me on a number of installs.
6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF
FJ10041
seems to cross to the tj14, that's what 'should' be in my tbi.
acording to spreadsheet,
56 pph @ 10psi
Looks like I should be able to just use it as is?
No need to re-invent the wheel. But we can make it better
It sounds like the 56 lb/hr injector is a good match already. If I were making the regulator inactive by removing the spring I would probably duplicate what GM did on the Crossfire setups and install a sleeve or shim in place of the spring. I would be worried that fuel pressure could cause the diaphragm to rupture.
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