Is it possible and worth it to switch my '86 carbed 305 to TBI?

 

Yes it is possible, but you have to do your homework. There are a lot small details that must be addressed. Plus, it takes time and money. I'm doing carb to TBI conversion - being able to work on my project only on weekends - its on month six!

//RF

 

I did a carb to TPI conversion, using ebay, junkyard, and new parts, and a Painless harness in about 2 weeks. Depends on how much you want to commit to the project, and how many things you forget about! It's the little sensors that will kill you when you have to order them.

 

yeah. I'm still trying to decide if I wanna try it. May I ask what the point would be to switch from TBI to carb?

 

Up to around 375 HP your ok with TBI, after that, it takes some finesse to get the single TBI systems to provide enough air and fuel.

Keep in mind that you'll need:
-EBL, 93-95 TBI truck PCM, or similar aftermarket system, I can tell you from experience that the stock TBI computer sucks and you likely wont be happy with it with a performance oriented setup. If you plan to just keep the LG4, then a complete stock f-body TBI system will actually be a good match.
-Prom burning equipment + laptop so you can calibrate it to your motor
-Applicable wire harness
-All sensors
-TBI and carb manifold adaptor
-EFI pump and fuel lines
-All needed cables and brackets to connect to the TBI
-Lots of odds and ends like fasteners and such

Id budget at least 600 dollars unless you get a good score at the yard or on evilbay.

 

Yeah, it's not for the light-hearted. My project went 9 months before it ran again. Then it was time to START tuning. I haven't finished that yet.

With a WideBand o2, new ECU and mostly new parts...drum roll........$2000. That includes the fuel lines, new pump, pump mounting unit, fuel filter, tools to fabricate new fuel lines, tools to fix the things I broke, more tools, more wires, more fittings, more sensors, the gas it took to get stuff, and the shipping costs to mail stuff here before the next weekend rolls around...and that doesn't even count the TIME it took, and the blood I've lost.

And guess what...after ALL of that, I went to close the hood after it started...and my air cleaner now rubs on the underside of my hood.

But being able to get better gas milage than the factory on a 120K mile powertrain...priceless!

 

Pizza_guy

You are beautiful! At least you have given me a ray of hope. I am at about the same amount, on month 6, but I also have dual tanks, a fuel plumbing system that can rival a jet airliner and I am yet to punch 52mm hole in my firewall for the ECM harness! The hole punching is scheduled for this weekend. It is moving forward, but one small step at a time due to time constraints and ‘honey do’ list.
//RF

 

My old LG4 CC Qjet got 15 mpg with 2.73's. I now get ~19 mpg with my current combo. I probably have $1400 in the whole setup but I got lucky and bought most of it from a friend. It pays for itself in fuel and cold starts

As stated before, it's not a project for the light-hearted. There are alot of details that need to addressed.

 

I did the 4 barrel to TBI conversion on my 1982 trans am. Well worth any hassles that were involved. However there wern't many of them I used all 1990 parts and everything fit the car perfectly.

 

i'd say if you plan on putting in a big motor or having a lot of horsepower just stay with the carb.

 

Why would you say that? How does the size of the motor or the amount of horsepower make a difference?

Not to be mean, but curious about your comment.

 

The BBC TBI is comprable to a 600-650 CFM carb. Whatever you can make with that, you can make with TBI.