jvaughn

iTrader: (1)

Hello Everyone,

I am going to be doing a 305 to 350 swap and have some questions. I currently have a 91 RS with a 305 TBI in it, with a T5 trans. I purchase a 350 L31 Vortec with less than 80k on it, that came out of a 02 Express 3500 van. I am planning to install a LT4 Hot cam and springs to increase lift. I will also be changing out the timing chain to gear driven timing. Heres my options:

Option 1:

Keep the fuel injected intake, upgrade the injectors, get a ECM/PCM and let it ride. I have the harness that is attached to the intake but beyond that I dont have a ECM for this motor. My questions for this are:

1-What ECM/PCM will work? Ive heard that you can use a ECM from a 97 Camaro SS, but i dont have the T56 tranny.

2-What size injectors do I need to go with here?

3-Is it worth the hassel?

Option 2:

Switch out the intake to take a carb, slap a carb on it, put in fuel line PSI reducers, and burn some tires.

Im really drawn to the fuel injection for fuel economy, but its not a daily driver. I feel like the first option is going to be more expensive, and Im wondering if its worth it. Also wondering if Im losing or gaining any performance going to injectors.

Anything im missing here? Ive done a TBI to carb swap in the past, so Im pretty familiar with the process.

Any help or opinions would be useful.

Thanks

vetteoz

iTrader: (13)

http://www.summitracing.com/parts/wnd-7542

plus the HSR fuel rails
See
https://www.thirdgen.org/forums/alte...tive-fuel.html

The ECM and harness from 90 -92 TPI car with a custom tune

bestracing

I'm not a big fan of gear driven systems. I've read an in depth tech article comparing chain, gear and belt timing systems that was in National Dragster magazine. Turned out the the gear timing system was the worst out of the three. The harmonic vibrations from the crank is directly linked to the cam through the gears causing the worst timing fluctuations among the three. This is with a cam driven distributor ignition.

Now with that said, I doubt you would notice any performance difference on a street driven vehicle. Just a litttle FYI

Since you are already talking about a new ECM/Injectors and some other add ons have you considered just getting a TBI kit that comes complete with ECM and tuning software? I just hate the thought of putting effort into a motor swap and then step backwards with older technology that you can't program easily and is becoming obsolete. Just something to consider.

jvaughn

iTrader: (1)

Never thought about a TBI kit

NagleMac

iTrader: (1)

He'd need to do fuel pump and all that too.

RyanJB

I basically did the exact same swap except I converted mine to an HSR TPI system. Going to a carb will save you some money and make tuning much easier.

Pocket

iTrader: (24)

As much as I love fuel injection, I can't in good conscience recommend keeping the stock L31 spider injection. A vortec carb intake with a TBI adapter plate is the easiest

Using a 90-92 TPI harness and a vortec EFI intake (any really) is the next step up without much effort

Beyond that check out the OBDII systems and other PCM upgrades. That's quite a step for a simple long-block swap though