Last week I converted from TBI to Carb, and wanted to know just how much it may hurt my MPG, so I did a test yesterday. Carter 600cfm w/750 jets and no cruise control.

OKC to FSM, or for you NON pilots, Oklahoma City to Ft Smith
1st leg 208 miles, all highway with one stop avg speed 75mph, gals used 8.1 mpg 26.9
2nd leg FSM to OKC, with some city driving and heavier traffic. Miles driven 218, avg speed 75 mph gals used 8.8 23.6 mpg. Combined trip total 426, avg mpg 25.2. With my tbi setup it was 27.5mpg avg. with cruise control.

 

you arent gonna beat FI in the gas mileage war.

but, you can always tune your carb for more mileage. With a carter this is as simple as a rod change. Most of your driving will be on the second "hump" (forgive me i dont know the technical name) of the rod, just find a set of rods with a hump that is of larger diameter
and make sure you have the stock spring for the rod piston thing

 

I had about the same results, I lost about 2 mpg. Glad to hear it man, congrats

 

Pablo, you are right, but hey I only lost about 10%, not bad... NOT BAD at all. Next test comes next race season when I see how much more fuel it'll take to do 6 laps. With the TBI setup it took 1/4 tank to do 6 laps at racing speeds. Due to the pick up, in the tank, I have to have at least 3/8 of tank of gas in order to do a lap without unporting the fuel.

 

Sean, which Carter 600cfm carb are you using AND is the Edelbrock 600cfm equivalent???

What are your highway RPMS?

What are your head/cam/exhaust specs, please.

Are you 305 OR 350?

[This message has been edited by FastBroker (edited November 10, 2000).]

 

yeah im in the process of doing a rebuild on my 305 and am going to carb from tbi. I was thinking about getting the carter. Did u notice a differnce in torque or power?

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91 RS' TBI 305
mods:
dynomax exhaust, lakewood control arms, gutted cat, pioneer deck, tbi spacer, jet stage 2 chip, K&N four inch element and open element, accel cap and rotor, moroso plug wires, msd blaster coil, bosche +4 spark plugs. Alot more mods to come!!(update 11/01/00 pulled engine
visit my page http://www.geocities.com/motorcity/pit/8410

2001 camaro SS LS1 onyx balck, SLP dual/dual center exhaust which brings horsepower to 335hp and 350ftlbs of torque, T-tops, 6 speed, Hurst shifter, cags!, power everything

 

In my whole 200,000 mile history, I have always got 27-28 Highway on my LG4 Qjet.

Are y'all telling me that FI gets better?

I remember when I purchased my car new in 1986 that the EPA mpg was higher for carbs than TPI.

My 93 Six speed LT-1 Z and 95 auto Vette never get that good, of course not comparing apples to apples here.

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1986 Black/Gold LG4 Z28
Original Owner, 200,000+ near trouble free miles.
Mostly Stock.

1995 Dark Red Metallic Corvette Coupe Original Owner

 

Fastbroker, sorry for the delay in answering, but been out working in miami for 10 days.

Anyway in answer to which carter it is, the only numbers that I can see easily are on the front left, as you're looking at the carb, 9605S 1225. I do know it's the 600 cfm dont thinks it's the comp afb tho. It has been re jetted with 750 jets tho.

I lost a little low end torque, but got it on the other end instead, where I neeeded it anyway. It's on a 305 right now, but when it's time for the engine swap it'll be on a 350.

 

Z28wiz,

Low end accerleration is a little less than I'd like, but the upper power band is perfect. I road race the car, so I needed the power there more than at the low end. Am at 4500 to 5500 rpm most of the time.

 

Fastbroker,

sorry stock cam, heads.. exhaust is hooker shorties, and I did install 1.6 rockers.

 

Sean, what are your highway RPMs?

 

at 85 indicated, 2400 to 2500 rpm.. but am only actually doing 75 +/- 2mph.