1988-305-tbi

so i made my adjustable reg. today, best $.32 i've everspent "set screw"
and i was looking on ebay and saw this aftermarket adjustable reg. it says that it has a pre drilled hole so you can hook up a vacum line to it which will allow 5 psi more at wot so at idle you can have it nice and mellow till you mash the gas and the vacum rases the the fuel pressure some how now i want to find out how to do this. i cant imagine how vacum could some how rase the spring tension in the regulater to give higher fuel pressure. does anyone have any ideas????????????????????????????????http://cgi.ebay.com/ebaymotors/NEW-G...mZ260053082376

1991CamaroRslow

iTrader: (3)

It works exactly like our TPI regulators, the vacuum assists the spring in pulling the regulator open, when you floor the car and the vacuum drops in the intake to atmospheric pressure the spring drops and pressure increases.

1988-305-tbi

thanks for the reply 1991camarorslow.......so i guess i need to look at a tpi reg. and see if i can fabricate something to work with my regulator. any ideas? i'm thinking about goin to the junkyard and getting some 350 injectors if i remeber correctly the 305 injectors are rated at 47 pph "pounds per hour?" right? and the 350's are rated at like 51/55/65. if i run the 51's would my computer be able to adjust accordingly or is it to much for the computer to compensate? plus would it even do anything or would the O2 just tell the computer to fire the injectors less, leving the car running the same as with the 305 injectors, any benefits, like a little bit better top end?

BMmonteSS

Absolutely no benefits what so ever by swaping injectors and fooling around with vacume adjustable fuel pressure regulators. How do you know your motor need mor fuel right now? I would start by getting a datalogging cable and doing some reading on DIY prom tuning. Once you know what your motor is doing now you can decide if you need to start making changes. Also the correct way to make changes is in the chip. You can add and subtract fuel and 100 other paramaters in the chip. If you run out of room to turn up the fueling, then it would be time to change injectors/ fuel pressure. Making changes without letting the ECM know about it is not a good idea.

It's kinda like taking off driving for a trip before you decide where you want to go.

1988-305-tbi

i beg to differ just by turning up the fuel pressure it feels like a different car with the pressure all the way down the motor gives up at 4,000 rpms with it all the way up it bogs a little at the bottom but pulls to 5,500 rpms, now i can peg the 115 mph speedo to the trip odometer peg, "125-130" and it still pullin, not hard but pullin none the less with low fuel pressure im lucky to get it to 110, and the tach just stays at 4500 or so, plus i'm not really looking to fully tune this motor i just want a lil more power till i do my ls1 swap next summer, it's not worth messing aound with it too much "money and time wise" seeing as that it will be finding its way to a metal recyler pretty soon

BMmonteSS

Your probably covering up for another problem with the extra fuel pressure. A stock LO3 won't make any more power by cranking up the fuel pressure.

I'm not just saying this because "I think" or it's my "best guess". I've actually tuned a couple of different LO3's once you get into dataloging and burning chips you'll realize what I'm saying makes all the sense in the world.

1988-305-tbi

my car isnt stock it has tpi heads, headers/exhaust/ aftermarket chip/ ultimate T.B. + spacer, my car takes out lb9 irocs on a regular basis, with ease, i wouldn't call it stock

Fast355

iTrader: (2)

That is just one more reason you need to get into chip tuning. I would build the WinALDL and make some datalogs to see just how far off things are. You would be suprised how poorly even stock L03s run on the stock L03 calibration.

This is an internally stock, bolt-on (1.6:1 rockers, Edelbrock 3704 intake bored 2", 46mm TBI unit, Headers, Duals, chip tuning) L05 350 TBI in a 5,300 lbs G20 van with 3.08 gears.

http://www.youtube.com/watch?v=UEeZ5ruugWA

http://www.youtube.com/watch?v=PX5Av4pS1RA

http://www.youtube.com/watch?v=c4CY3PvklvM