Got the 350 and t-56 in the car the other day. the motor has a LT4 Hotcam 190cc aluminum heads 1.6 rockers torker II intake edelbrock headers and 3in cat and flowmaster cat back. I'm not sure about the the injectors and the oddball tbi out of a 454 cargo truck if i fire it up and the fuel go's up to 40 psi I need some new injector or if its around 12 or so I got the 80pph and I'm good. I got a 60psi 225 fuel pump How much psi should I run? Would gutting the regulator in the tbi and plumming a aftermaket regulator in to the return line be a good idea? Open to other ideas or things to watch out for.

 

another pic

 

I didn't quite follow you on the questions you asked, but I would start with the small injectors if I were you. There's a good number here who vow that you should get all the injector possible, but I'm tellin you, the chip tuning headaches aren't worth it.:nono:

Get the AFPR and start with 55# and work your way up if you can.

 

the AFPR will not fit my tbi, ummm I don't think 55's will suport this motor.

 

yeah... Its going to need all the injector you can give it.

Those are the small style injectors. Id say theyre probably 60 pph each at the stock tbi fuel pressure. According to delphi theyre max operating pressure is jsut over 100 psi. Although Id probably keep it under 60 psi as Im not sure what the diaphram in the regulator will stand. If that blows out its car fire time. If teh canister that houses the spring allows fuel to gush out all over the dist. itll look like this: https://www.thirdgen.org/techbb2/sho...hreadid=263447

Id stick it at around 40 psi if it isnt there already and work from there. If you wish to go higher then make sure that canister is sealed so the fuel has nowhere to go if the diaphram blows. Most will say itll be fine but for me its extra insurance on a high $$$ buildup. I had one partially fail and it dumped fuel all over the intake. Luckily nothing came of it.

 

I vote for higher pressure as well. I'd start with 30psi and an injector constant on the safe side 95, make a VE table that peaks at your projected peak torque RPM and start moving the injector constant around to get the BLMs in the 120's. Oh yeah, and make the highest VE around 95 for starters.

Dim, the pressure regulator diaphram shouldn't blow out unless you've got some return line issues. The diaphram is subjected only to return line pressure, metal diaphram that rests on the supply side can't "blow out." I feared the same thing for a long time until I took the regulator appart and figured out how they designed it. Very compact but no diaphram issues, only lack of spring pressure . My spring looks like a small engine valve spring , had to remove the adjustable spring seat to get the fuel pressure from 36psi down to 28... set it and forget it.

 

The ones on the stock tbis are subject to full line pressure as the return port in the pods leads directly off of the injectors. In those its the increasing fuel pressure that pushes teh diaphram/spring back and allows the fuel to return to the tank.

If the holleys/new tbis are a different design then thats a real boon as one can run what ever they want. I certainly hope so. Be really cool to have 40 and 50 psi without having to worry about it.

 

Once again my odd ball tbi defies logic and has a ruber diaphram and a metal plate that covers the inlet held down by the spring. the Diaphram is subject to injector pressure and not return line pressure. Unlike most gm and holleys the canister is vented and not sealed. One good note is that it has a greater range of movement on the regualor screw.