Hot Rod Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Hi guys this is my first post and I have a question about the TBI I have a '77 k10 with 305 out of a '75 Camaro and I have already installed a K&N air filter and hooker headers what do I need and what am I going to have to change it to tbi so i can hopefully get better MPG's.
 

·
Registered
Joined
·
3,107 Posts
Mileage wise. Really not worth it. You might see 2-3mpg gains.

Drive ability wise TBI is worth the headache and $500 for the harness and standalone ecm.

But, you really should be starting with a 87 to 95 truck engine if you want tbi.

No headaches with the different angle on the intake or guessing what cam gear to use with the tbi distributor or issues with the cam/valves working with the factory tbi.

Keep the thing carbureted or grab a tbi engine to start with.

Or email the company below.


Below is a link to a Michigan based company that makes standalone TBI kits. They can also install tbi on almost anything having it working like factory. After a few emails.

TBI harness, chip, and ecm to run a factory TBI engine((you supply the fuel pump( use a 87 squarebody saddle tank)). $500

Or you can take virtually any stock to mild SBC and they can give you everything you need to run it for around $1300.

If you say have a more built engine like say a 383 or a 468 then we get into the heavily modified NA setups. In which your going to have a few emails and a build sheet would be nice. But they can make that run TBI also with replacement parts that you can find at any parts store.
 

·
Hates: Liver. Loves: Diesel
Joined
·
5,743 Posts
If you're talking about a factory GM TBI, you'll likely lose MPG. Thousands of TBI guys swapped their TBI for a Qjet and picked up HP and MPG.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
If you're talking about a factory GM TBI, you'll likely lose MPG. Thousands of TBI guys swapped their TBI for a Qjet and picked up HP and MPG.
well I'm not into the performance i just need a type of fuel injection because i drive 167 miles almost every week to visit my gf
 

·
Hates: Liver. Loves: Diesel
Joined
·
5,743 Posts
Re-read what I wrote. Why would you choose a TBI that might give you LOWER mpg? It has nothing to do with performance. You asked about TBI to get 2-3 more mpg. You likely won't. "just need a type of fuel injection because I drive 167 miles" doesn't mean that any injection system will give you what you want. Fuel injection isn't a magic bullet that saves fuel. The engine will still need the same amount of fuel to match the air that flows into it. EFI can help mpg, but that isn't it's main purpose. Put it this way.... your 1975 small block doesn't get bad mileage because it has a carburetor.... it gets bad mileage because it's a 1975 small block. EFI won't change that.

If you want it for easier starting, or cold weather use, then great, but as an efficiency plan, it likely won't help.

To swap to a TBI, you'll need basically all of the TBI equipment; computer, distributor, TBI. You'll also need to make sure you have all the appropriate sensors. You'll either need to fabricate a way to get the TBI fuel pump to work, or plumb in a new fuel pump with a pressure regulator giving you the right pressure for the TBI. The big issue you'll have is the intake manifold. GM TBI uses a funky 3-bolt triangular pattern. There may be some adapters on the market, but if you get the TBI intake manifold, it won't fit on your 1970s heads.

If you want to go for it, I say do it. I'm all for doing things the way you want. I simply am letting you know that it likely isn't a wise choice for your mpg goals.
 

·
Registered
Joined
·
673 Posts
You'll either need to fabricate a way to get the TBI fuel pump to work, or plumb in a new fuel pump with a pressure regulator giving you the right pressure for the TBI.
Here is my 2cents about the fuel pump: with my TBI engine, I use the external pump from a 1989 Ford Econoline (this vehicle has 2 fuel pumps, 1 in-tank, 1 outside), without a pressure regulator. Easy to connect too, just slip rubber hose on the fittings, and a clamp, nothing fancy. Works great, I have had a junkyard pump in my truck for 7 years! Just mount it at the same level as the bottom of the tank.
 

·
Registered
Joined
·
2,592 Posts
If you buy a new carburetor and tune it and the engine up, you will spend less money and get just as good performance and mileage as a TBI conversion.

Exactly what carburetor and intake do you have now? Is it a stock Quadrajet and iron intake from the Camaro? For a simple swap to get better gas mileage I would look at the Edelbrock AVS2, which seems to work a lot better than the older 1406. Then make sure the ignition and timing advance is working correctly, especially the vacuum advance (it’s main purpose is highway mileage).

Bruce
 

·
Registered
Joined
·
3 Posts
Hi guys this is my first post and I have a question about the TBI I have a '77 k10 with 305 out of a '75 Camaro and I have already installed a K&N air filter and hooker headers what do I need and what am I going to have to change it to tbi so i can hopefully get better MPG's.
TBI is quite finicky about cam choice...even a split duration "RV" cam can throw things way out. TBI is completely dependent on MAP signal, and is looking for specific vacuum values at specific load and RPM. Sure, somebody can "burn a new chip", BUT without having vehicle on a dyno, you never know whether you're creeping up on the desired or not. I worked on a fairly mild 358 (15.5"hg at idle) for about 1 1/2 years, even going so far as burning my own EPROMS for the 7747 ECM, and evaluating and logging data daily. Never came close to the drivability I wanted. Pulled the TBI off, replaced with a dual plane manifold with a 650 vacuum secondary Holley and HEI ignition. Left pump in tank, used a bypass regulator set at 4#, returned rest of fuel to tank. Changed jets, pump shot, and GAINED about 4 MPG. Drivability on the street was much better, and no vapor lock.

Joe S
 

·
Registered
Joined
·
3 Posts
Discussion Starter #10
TBI is quite finicky about cam choice...even a split duration "RV" cam can throw things way out. TBI is completely dependent on MAP signal, and is looking for specific vacuum values at specific load and RPM. Sure, somebody can "burn a new chip", BUT without having vehicle on a dyno, you never know whether you're creeping up on the desired or not. I worked on a fairly mild 358 (15.5"hg at idle) for about 1 1/2 years, even going so far as burning my own EPROMS for the 7747 ECM, and evaluating and logging data daily. Never came close to the drivability I wanted. Pulled the TBI off, replaced with a dual plane manifold with a 650 vacuum secondary Holley and HEI ignition. Left pump in tank, used a bypass regulator set at 4#, returned rest of fuel to tank. Changed jets, pump shot, and GAINED about 4 MPG. Drivability on the street was much better, and no vapor lock.

Joe S
I think I would be better off with a 6.2L diesel
 

·
Hates: Liver. Loves: Diesel
Joined
·
5,743 Posts
You would probably instantly double your MPG with a 6.2L. Mine pretty consistently got 22mpg empty in a crew cab dually. Same for my 6.5TD and really close to that with the Duramaxes.
 
1 - 12 of 12 Posts
Top