[DougGass87]

what would be the best setup for building a fuel efficient SBC that still has decent power?

[454mikey]

I will tell you my setup i'm happy with and let you decide if it is right for you. It's got flat top cast pistons, 76cc ported heads, comp cams extreme energy camshaft 480in. 490ex. edelbrock rpm intake 750 holley carb. also hedman headers and 308 rear gear. it runs on 87 octane, dynoed at 368 HP, and gets 14mph in town. also it has a pertronix dist. What fun is this to drive! NEVER A PING.

[DougGass87]

what size engine?

14mpg city is lovely, what about highway?

[firestone]

I had a 355 with vortec heads and an xe268h cam (224 230 @.050 duration). Most dyno results for this combination are between 375-390 hp. With a 3.90 rear gear and a overdrive tranny it got around 17 mpg on the interstate. I am sure that a smaller cam would get better mileage though.

Adam

[DougGass87]

well, it's going in a 56 chevy pickup and will be running a 700r4 and 2.something gears....

would love to be able to get 20mpg on the highway...

[mytruckownsit]

What do you have to work with. Got a core already.

Ross

[DougGass87]

i have nothing yet....except the rearend that im sticking with.....

thats why i just said SBC, didn't specify what size or anything

[firestone]

I had a 700R4 also. I would try to find a set of gears in the 3.3x-3.4x range. My car was right at 3000 RPM at 75 mph in overdrive. I think it would be beneficial to get that number down to around 2500 RPM. I dont think you want to go too low though, and bog the motor on hills and such. It may, in that case drop into 3rd, and really start sucking gas. Also, going with a cam a step lower than mine would also help. I think those two things may pick up the extra 3 mpg to get you to 20 mpg.

Adam

[astroracer]

Look for a pre-vortec 350 TBI motor out of a truck or van. '93 -'95. Fuel injection is the way to go for good mileage. My '95 Sierra has a few minor mods, headers, good exhaust, TBI spacer and a Jacobs Pro Street ignition and it gets around 25/26 on the highway with 3.42 gears.
The 4 spd o.d. trans will be a neccessity also. Get the whole wiring harness and computer to go with it.
If you have to build a motor build it to produce low to mid-range torque. That is where you will see your biggest useage and the lowend helps to get the car moving.
Steeper rear gears will also be better to help get the vehicle moving. Mid three series like Adam said will be perfect for off the line grunt AND mileage when locked up.
Mark

[DougGass87]

well i am trying to stay far, FAR, away from fuel injection.....wires suck

so far i am thinking:
-get a bare block from the junkyard and have it machined
-put in a summit 355 rotating assembly with crank and stage 1 rods
-76cc heads
-edelbrock intake
-headers
-2.5" exhaust with Flowmaster 40's
-650cfm carb

then back it up with a 700r4

i am not sure what my rear gears are, but they are in the 2's i would imagine, its out of an old station wagon (thats all dad could remember, it was just so it could be towed from NC to here) pretty sure its just a 10 bolt, but it will have to last for now.........

[mytruckownsit]

If your going that route I would look at some other rotating Assembly manufactures like Powerhouse and Probe ect. those are just the P's

Ross

[DougGass87]

why? are they cheaper?

here is the kit i am talking about

looks like a good kit to me......

[cornfieldcars]

I would imagine your rearend is probably a 2.73. The rearend I put in my pickup is a 10 bolt with those gears. I'm hoping as you are that I can get some decent mileage on the highway.

barry

[mytruckownsit]

Yes they are cheaper. For that money you could get the same kit with better rods including the balancing. Hell you might want to think about doing a 383 the cost is maybe 100 bucks more, even less if you Clarence the block your self. Here's a forged and balanced 383 kit from powerhouse for less money 928.00$. Probe also has a similar kit...

Powerhouse 383 kit

Ross

[Hippie]

Originally Posted by DougGass87

well i am trying to stay far, FAR, away from fuel injection.....wires suck

so far i am thinking:
-get a bare block from the junkyard and have it machined
-put in a summit 355 rotating assembly with crank and stage 1 rods
-76cc heads
-edelbrock intake
-headers
-2.5" exhaust with Flowmaster 40's
-650cfm carb

then back it up with a 700r4

i am not sure what my rear gears are, but they are in the 2's i would imagine, its out of an old station wagon (thats all dad could remember, it was just so it could be towed from NC to here) pretty sure its just a 10 bolt, but it will have to last for now.........

Decent performance with good mileage in a heavy non-aerodynamic brick and no EFI ( but EFI is THE way to go):

5.7 roller cam shortblock
Hypereutectic pistons with an 18cc D-cup reverse dome
5.7 TBI heads (64cc chambers)
GM Ramjet 350 roller cam (you can find new crate motor take outs on Ebay CHEAP, got mine for $50 brand new)
Edelbrock Performer to fit the TBI heads
Q-Jet carb
1-5/8" try-Y headers if you can find a set for your chassis.
700-R4 with about 3.36 gears.