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Discussion Starter · #1 · (Edited)
Ive got a 73 Malibu that is in pretty good shape that needs front suspension and a drivetrain. Ive got a 4 spd trans that is overdrive that will drop right in and im getting a tired ol 350. What would be the best way to build this as to get good gas mileage without going to fuel injection. Figuring that the engine is gonna need a complete rebuild and maybe new pistons and a bore but hopefully ill get away with a hone and rering.

Gonna need Ideas on...
Carbureator
Intake
Cam
and such...



 

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Mileage is all about using the fuel efficiently. This means as much compression as possible that will reliably work with the intended fuel octane, a small duration cam to make the engine efficient from 1500 to 3500, and a well matched induction and exhaust system.

When you mention hoping to rering it brings a strong message of the project having a finite budget, which is fine but ultimately there will be a trade off compared to maximizing the build.

Assuming you have a smogger headed 350 with the quadrajet carb and a small budget, I would deck the block and mill the heads to achieve a true 8.5 to 1 compression. I would retain the Qjet carb but consider a performer or equivalent intake manifold. I would use a Comp extreme energy 252 camshaft and small tube headers.

A midrange build would include vortec heads, all other specs remain the same

A big budget build would include E Tech heads from Edelbrock (170's), a zero decked D dish piston at 9:1 static compression and a short duration high lift hyd roller cam.
 

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Having had a Performer intake I can tell you that a cast iron 1969 factory intake is better for low rpm torque. Other than that, I agree.
 

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A lot of getting good mileage is with the driver. Keep out of the back 2 barrels of the carb. Drive like there is an egg between your foot and the gas pedal. Back in the day we would put a vacuum guage in the car and try to drive with the highest reading on the guage.
 

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A modified Qjet intake will make more power than the performer and hold more heat, witch helps with fuel atimazation , run the factory snorkel air cleaner with a heat riser tube hooked up..To heat the incomming air...Put a real good tune on everything and keep your foot out of it.

If there is no ridge and no rust or huge scratches in the cylinders .You can get by with E251K rings and not have to touch the cylinder walls..

If it has dished pistons , get some flattops 345np cheap and strong.
Yes deck the block , get that compression up there

I go over on my personal cars compression 10.4 minimum on sbc daily drivers But the 268h is my minimum cam
I ran a 268h years ago with 9.0 to 1 and qJet intake and carb 350ci and 308 gears no od and pulled 20.5 mpg and 18mpg hot rodding a few times on 87 octane
It ran 14.50 at 100mph with a th350 using 1st and 2nd gear only Stock converter ported exaust manifolds and bowl blended 624 heads 3800lb car
changed to 370 gears in a 9" and got 15 mpg and ran 13.75 at 101mph
 

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if you are as lucky as i was when i did my first engine rebuild, then get yourself a Northern rebuild kit and get the base cam- the .390/.410 lift one- and run your stock heads with the dished pistons.
i did that in a 76 Monte back in '93, and with an old Weiand high rise square bore intake with a qjet bolted to a Mr Gasket adapter plate, and had some rusty old 1 5/8" headers with 4 feet of 2.5" exhaust tubing off each collector going back to a pair of Thrush Super Turbo mufflers. i had a home made dual snorkel ram air setup feeding cold air to the carb- after a 10 mile highway drive on a 90 degree day, the carb was really cold to the touch..
with the stock 2.56 gears, that thing would get an honest 30mpg. i don't know how or why, but it did it. gas was right around $1 a gallon, and $5 would let me drive around all weekend long. it wasn't a speed demon, but it wasn't a total slug, either. it was a good combo that would idle at 500rpm in gear with over 20" of vacuum.
 

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and block off the grille opening as much as it will allow before it runs too hot. this way, the air is diverted up and over the car instead of building up under the hood and causing extra lift and drag. you can block the entire grille if you put a small spoiler under the radiator support to jam some air up thru the radiator at speed. also, put something- like foam or some sort of weatherstip- between the hood and radiator support so the air that does get into the engine bay goes thru the radiator.
 

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bluechevelless,

Go with a great cylinder head (like the Vortec), get a mild camshaft, use a factory intake or the Edelbrock Performer (I use a 1969 Corvette intake), use as tight of converter as your cam manufacturer recommends. Make sure that you use a
vacuum advance.

As far as carbs go, I really like the late sixties Quadrajets like the 7029207 (1969 Corvette). I've also had great luck with running Oldsmobile (7043250) and Pontiac (7045263) quadrajets, which means that if you can't find a cheap Chevy Qj core, you've got other options. I haven't had as good of luck running the '77-'79 model year Chevy Quadrajets. With some tweaking, I've been able to hit 18 m.p.g. regularly driving back and forth to work.

Here is a link to a little test I ran between some Quadrajets and a Holley regarding fuel economy:
http://www.chevelles.com/forums/showthread.php?p=477712&highlight=7029207+6619#post477712

Sounds like your trans set up will be hard to beat. Add a nice, free flowing exhaust system and you should have it nailed.

You can have performance with economy. An added benefit is that a clean running, efficient engine will probably last longer than a fuel hog.

Mike
 

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73-77 Malibu's are heavy, so I'd also try to lighten the car. Maybe a fiberglass hood. My friend got between 22-24mpg from his 77 Monte on a trip to Florida. It had 350 with stock Qjet, 2:73 rear, and TH350. It had a vacuum gauge stock, so we keep the engine running at max vacuum. It can be done.
 

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Discussion Starter · #13 ·
thanks guys ill have more information on the engine when I get it picked up and apart. I have a few tricks on getting the malibu to look better and loose some weight. It was originally bought as a parts car till we decided it was too nice. It need front suspension BADLY and the interior isnt good but ive got a few things I can throw in there. Its an AC car and I will probably hook it all back up with new seals. The interior will need to be gutted and it needs a steering column and a few other little things. I have a wheel and tire set to throw on it. We looking at another not so nice 73 trying to get cheap for parts for this and our other SS 454 73 chevelle
 

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Danny,
I had a 68 that did well at the pump. So I kinda have an idea about the "lighter" side of the beast. I suggest cleaning that block up as easy as you can, just enough to make sure the bores are clean. Flat top 9.0 pistons, easy cam, HOT ASS distributor, use really good quality wires, small 4 barrell, headers, use that OD tranny, put some 2:70 gears in the rear and you are surely lookin at 18 to 20 if you can stay out of it......
It won't boil the tires, but you won't make Texaco rich either.
 

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I am hoping to get real close to 20 m.p.g. with my 468 - before you start laughing - I have a little bitty 600 emissions Holley, 2.73 limited slip 12 bolt and a vacuum gauge. I used to have 4.10s and did not see double digits. Gas hit and stayed over $3 so I switched to 2.73s and checked my driving habits to get better mileage, I now get 14 honest MPG in mixed city / highway driving. You can definitely get over 20 mpg with a decently tuned small block. Now my '68 feels like it is always starting out in 2nd gear, but it is actually much more drivable and I think overall the engine has the torque to move that car with that tall of a gear. A 700 Trans. with tall rear would be even better, make use of the deep 1st gear to get you off the line and use torque to lug it down to real low rpms on the highway.
 

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yeah, back in the 'good old days' when gas was $2, I really didn't care and got an average of 8 MPG. Nothing like getting sideways mashing the throttle at 40 MPH. Now I'm older, wiser and gas is $4 so the 2.73s went in. On the good side, I think I could more than double the top speed on my stock speedo!
 
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