how to reach power + good mileage with a 318...

[ValerianMagnum]

reach 300 hp / 300 ft pd tq and good mileage with a 318...

its a 74 engine with a 2bbl . completly stock,

i want to put it back in my cuda and have a great driver ...

ive always heard that a 318 with taller gears ( 2.94 -3.23 ) isnt that bad on gas...

or i am better off buying a 5.2 magnum and convert it to a carb set-up..

my goal a reliable engine , that is 318 c.i. , and a good mileage , smooth roadster ...

what do you guys think...

 

[AdamR]

The 5.2L magnums run great if you can start with one you'll be ahead in the long run "if" it doesnt need a rebuild. Just slap it in and swap on the 4bbl.

The 318 in my car is getting a stock 73 thermoquad and 340 intake, a small cam around .450-.460" lift and thats it.

 

[ValerianMagnum]

enough power ?? and is it hard on gas ? i have a 5.9 and its verry reliable ...but i know that it depends a lot on your gear ratio !

 

[BillGrissom]

Electronic ignition for sure. Computer-controlled fuel and spark is the easiest way to get power and good mileage. If you use a carburetor, a spreadbore is best - Thermoquad or Quadrajet, though TQ's are a bit big for a 318. It is also hard to find good ones, or even rebuild kits.

 

[67Dart273]

Here's a real world example from the last century

During the FIRST gas crunch of 72-73 whenever it started, and due to other reasons, I swapped a low-miles junkyard 71 340 into my 70 440sixpak RR body. 3.54 Dana, A-833, and Hedmans on the 340. No mods at all to the engine, other than playing with TQ, Quadrajets, and Holley spread bore.

This car weighed 3860, and that engine gave me 17.5 MPG on the highway. I am NOT an "eggshell" careful driver. Had "hang on" aftermarket A/C adapted from the 440 setup.

This was a high compression 340 (10.x : 1) and I realize that gas was supposed to be better back then

Even 360s can give you fair mileage. Friend of mine had a 74 Dodge W100 shorty wide box 4x4. That thing weighs close to 5K. Dual exhaust, either stock 2bbl or later a spread bore 4bbl would get just over 14 mpg empty. All we did was play with the timing and distributor a little. This was with 11:00 x 15 radials (BF Goodrich All Terrain T/As)

 

[AdamR]

The 5,2L that was in my 94 Jeep got 13mpg around town, it was all time 4wd and heavy but it still had no problems getting the Jeep to move. I would think in a lighter A body with better exhaust and a well tuned carb you could run 13s and still get good milage out of it.

 

[273]

If your rebuilding no matter what, I'd stick with what you got 318 heads are good for 300HP, 9:1+ compression, dual plane, 650 carb, headers and high lift 262 cam will get you 300HP but I'd find low k 5.2 the heads are good for 400 HP unported and stock HP is net 235HP (most built engines you see dyno'd are gross HP). So stock it pretty close to 300HP, dual plane with 650 carb, headers and with the engine having a factory roller you can get small duration high lift cam and 300-330HP for less money and room to grow 400HP+ latter.