CHEVY TPI question

[sawzall]

greetings..
I dont post here too often but lurk alot.. and most of you know me from the hamb anyhow..

I recently finished the install of a chevy tpi system into my 48 olds wagon.. (which we've dubbed "sticks")

the car starts and runs great, however I am concerned that I may have over done it abit with the injectors..
I believe the stock injectors are 18 lbs units.. when I installed the new injectors I ordered 24lbs injectors.. (the hotrodder in me might have gotten ahead of my common sense)

I know the ecm in this application maps the fuel curve based on the input from various sensors and based on that imput the ecm controls how long the injectors fire..

now heres the question.. by replacing the stock injectors with higher pressure units did I think I may have inadvertantly installed a componant that is creating a "rich" condition in the combustion chamber.. I feel this is the case because the car seems to run rich until its warmed up... (the exhaust smell etc)

anyhow can anyone with any thoughts on this subject post them here? Do I need to run out and get a new chip for this thing now?

Am I throwing too much fuel to the fire due to the higher pressure injectors?

if so I guess a custom eprom is in order..

FOR WHAT its worth the tpi is a speed density system on a gm crate motor. I believe the motor is the pre 88 replacement motor..

more photos of the project at
http://public.fotki.com/sawzallshop/

[choco]

The calibration in your computer expects the injectors to flow a certain amount of fuel. The flow rate you choose depends on the amount of air the engine can flow (that is, horsepower). By installing injectors with a higher flow rate, the computer still thinks they only flow 18lb/hr, but in actual fact they are flowing more. In a Mass Air system, such as the 86 - 90 TPI, the computer can compensate for this to a degree, but on a speed density system, you will be running rich all the time.
Replacing the injectors would be better, as you have not modified the engine in any way to use more fuel flow, so using the stock injectors is the way to go.
If you want to modify the engine with a cam, heads, etc, I would recommend that you replace the computer with a Kalmaker ECM, which is an Australian invention that uses a modified Delco ECM as a "Real Time Computer". You tune the engine with a laptop running the Kalmaker software. The laptop plugs into the Real Time computer, which is connected to the running engine. Once tuned, you can either leave the real time computer in the car or burn your own chip and use a stock Delco computer. Being Speed Density, our Aussie programs will work OK. For more info, see http://www.kalmaker.com.au
Alternatively, get someone who knows how to use the public domain software to burn Delco calibrations on to a chip. It's a hit-and-miss operation, but cheaper than Kalmaker (Kalmaker Street Pro 3 costs $AU1100 for the complete kit - Real Time Computer, software, cables, manuals, etc). There is also a public Kalmaker forum so Kalmaker users can share ideas and get help. It's at http://www.hotrodhandbooks.com.au/kalmaker/index.php

I've also written a couple of books on the subject. The SBC Tuned Port Fuel Injection System....



and the Engine Management System Reference Manual....



both available from Graffiti Publications (http://www.graffitipub.com.au) or Amazon.com

[sawzall]

i knew I was getting ahead of myself with the choice of injector.. thanks for confirming it.
sawzall jeff