hey guys, how can i set up my 427 or 454 up to get the best gas milage without giving up power? i read somewhere in here that one of you guys has a mild 454 that gets 18 miles per gallon. my setup is going to carburated, how can i tune the carb to do this?

1. Be conservative with the cam.
2. Do not over-carb it.
3. Run higher gears.
4. Look into getting an overdrive trans.
5. Drive with a lightfoot (I know it is hard, but is really the biggest factor)

That's a start. Feel free to add.

HTH,
Erik

Use a vacuum advance distributor. Mechcanial advance doesn't give enough advance for the best MPG.

Overdrive trans, lock-up torque converter, Quadrajet.

What kind of carb? Sometimes lighter jetting with bigger power valves can help.

Put it on a trailer, mine gets great mileage and runs 10's too, considering all miles :D

OD trany (WITH LOCKUP)with proper gearing/low to upper mid range cam with good trq/good breathing intake & exhaust(min of 2.5inch mandreall bent) with headers/q-jet setup properly/K&N air filter/heads with proper sized intake runners for fuel economy(oval port better than rectangle port in BBC fo MPG)/electronic ign system with spiral core wires(less resistance),hotter coil,split fire plugs(more efficient fuel burn/combustion),vac advance,mech advance curved for application,cap & rotor with brass contacts(less resistance/longer lasting)/KEEPING YOUR FOOT OUT OF IT FROM STOP LIGHTS IS VERY IMPORTANT FOR MPG & HALF THE BATTLE.

Basically just a well thought out pkg with porperly matched componants is the key.

Scott

Seen a few posts like this, and I always wonder why guys setting up a BB for power are worried about MPG? I know gas prices are high and only going to go up, but is this for a daily driver or something? To me a SB would be more economical if want something more streetable with power and better MPG. I guess you gotta pay to play...I mean where's the fun if you have to baby it to squeeze out a few more cents a gallon.

ya i hear ya, thank god its not going to be my daily driver.i read once in chevi hi perfomance, that this guy had a small block, that layed down 530 hp and 510 lbs, or close to it and his engine lays down like 23 or 25 miles per gallon! it was some wierd way they tuned his carb. ill have to look it up and post it.

for the carb im thinkin pf slappin on a holley 750 double pumper.

Im running a 750 DP on my 454 when I want to get great MPG I watch the weather channel and look for tailwinds and plan my route to go downhill as much as possible, make the wife run along beside the car and use my mainsail on gusty days.
Kidding of course. DPs are what they are and once you get your car tuned/dialed I would not expect great mpg from a double pumper.

Yea let me know where you saw that in Chevy Hi Performance, that sounds interesting. Is CHP worth a subscription? I already get Hot Rod, Car Craft and Super Chevy. Probably too costly but what about ditching the carb and going with fuel injection and a supercharger?

I have a 800 quadrajet on my Trans-Am and it only gets 9mpg. :D

NORMALLY YOU WOULD NOTE USE HOLLEY DBL PUMPER & GOOD FUEL ECONOMY IN THE SAME SENTANCE.

You can have your cake & eat it to a point these days when it comes to power & trq vs fuel efficiency with todays tech but a BBC with dbl pump holley is normally not it when it come to fuel economy.

Your in the wrong hobby if your concerned about that when talking about building BBC With dbl pump holley.

You need to buy a new 500hp vette that gets something like 25 or 28mpg which is amazing.

The new 300hp impalla gets something like 28 or 29mpg,awsome but i cant afford either of those cars unless i sell my #'s matching 69 ss 396 i have owned for 28yrs which aint gonna happen while i am alive.

Scott

Fuel injection rocks... enough said.....

well im not super concerned i just wanted to tune it the best i could, i mean it wouldnt hurt right? hey jyags, chevi hi performance is well worth the subscription, its not alot either i think i payed like 15 or 20 bucks for the year. its a good magazine.

aha! i found it! its the january 2006 issue of chevy hi performance. this guy has a small block that pumps 556hp and 512lbs! and gets 21 miles per gallon!!! they use a Innovate Motorsports LMA-3 Aux Box and a Innovate MOtorsports LM-1 Wideband tuning devise. and some other stuff like idle feed restrictor blanks, air bleeds. and it says you can tune the carb to ''off road'' and to your cam specs. it starts on page 56. check it out guys. it says you can get EFI quality from your carb! im getting this for my car!

Yeah, an LM1, and a carb you can tune easily. The venerable Qjet is a wonderful carb, but I would need a really detailed instruction manual to get the fuel curve just right. I honestly think fuel injection is easier, but if you know carbs, I think a fuel injection-like curve is possible.

I've had good luck tapping the main body for 8-32 brass set screws to work as air bleeds (drilled out to what ever you want). sure beats paying for a new main body.

I am also going to use the same method for the power valve channel restrictions (most likely use a larger set screw) and idle feed restrictions(use a smaller set screw) and the emulsion ports. I got my double pumper for $50 so Im not afraid to play with it, and I have a spare set of metering blocks.

I should also note I am using a LM-1 wide band air/fuel gauge.

I would love to play with a q-jet for my application but since my car is blow-through supercharged it wont work w/o major modifications (cant flow enough fuel)

hey grease fire what are you laying down in milelage? did you do your set up your self? if you did how hard was it to install? this is aa really good article on how to set up the wide band air/ fuel gauge. if any of you guys have the issue be sure to read it. it tells you the parts and tools you need. i think the tuner is like $590 and some tools like small drills and stuff, and the other tools are cheap. im definitly looking into this type of set up.

well im not super concerned i just wanted to tune it the best i could, i mean it wouldnt hurt right? hey jyags, chevi hi performance is well worth the subscription, its not alot either i think i payed like 15 or 20 bucks for the year. its a good magazine.

Nah I understand about the gas and tuning, I was just busting your chops cause I'm a SBC guy. Thanks for the tip about CHP...maybe I can find a back issue or on the web.

hahah yaot me.yeah look it up or subscribe, im glad i did. good tech articles and nice cars. :)

sweet, i found a 2-year subscription on ebay for $12. can't beat 50 cents an issue, even if i don't learn anything i'll have something to pass the time on the toilet.

for the carb im thinkin pf slappin on a holley 750 double pumper.
:sad: :rolleyes: :clonk:

Why build a big block for fuel economy? just don't think of it in "miles per gallon" instead think of it in "smiles per mile".
have fun with it,
Scott

I get a about 50 SPG with my 468CI ..You just have to know how to drive it right.http://www.highperformancetoys.com/forums/images/smilies/drivings.gif

http://memimage.cardomain.net/member_images/11/web/791000-791999/791497_7_full.jpg

Sometimes after Its just ate a Ricer its Gets 75 SPG!!:thumbsup:

mad hooker
my Innovative Motorsports LM-1 was about $350 if that is the "set up" you are refering to, it was very easy to install.

If you are refering to the mods on my carb: $5 for a 8-32 tap and $8 for 50 8-32 brass set screws and I dont remember the price on my numbered drill set. I had a spare junk main body to practice on drilling it and tapping it.

I get 14 MPG driving back roads (lots of 1/4 mile runs during these drives) mostly averaging 65 mph. Air/fuel ratio was running low 14's:1 and high 13's:1 this is with a 496, 800 double pumper, 3.55 gears, ST-10 four speed in my 72 chevelle. I think there might be a little milelage left in by dropping the idle feed resrictions and by playing with the vaccuum advance a little.

I still retain my WOT mixture by drilling the Power Valve Channel Restrictions and upping the secondary jets to get the desired mixture, you might not have to drill out the PVCR's since your not running a blow through carb.

I have yet to check milelage with the six speed.

thats all I can think of right now, hope this helps

hahaa smiles per gallon, good one i think that will really help. hahaha yeah i cant wait till my pumped 427 starts eating ricers, there will be plenty of smiles per gallon then. :)