The 4" bore of the 360 has always proven to be more of a gas hog than the 318, although the 360 can get decent mileage under the right circumstances. With either engine, you still have a V8, so there's that.
Small block mileage
- Thread starter dave ellis
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get a gear vendor no cutting , works really well have mine for 8 years now helps big with the MPG on the highway 70mph+ . I drive 100 miles a day in summer at $5.00 a gallon back then and $8.00 a gallon now it might not have paid for itself but sure helps and car drives nice with no rev induced headaches . What I really want is an 8 speed from a smellcat , still waiting . for that I'd cut the floor roof amything
was 2000.00 when I bought mine , buddy just bought one used for $800.00 Kanadian rubles pesos . It is worth it for just cutting the rev induced headaches IT'S MORE THAN JUST ABOUT MONEY car is a pleasure to drive on the highway , ride is as quiet and smooth as my Strange Rover supercharged POS , And twice as much fun to drive
Yeah but the GV over drive's OD ratio blows chunks, IMO. .78:1. May as well not have an OD.
It is about the money and how one installs it to there transmission. Themselves or via a mechanic which is more money.
Then there is the below….
First year of the 318 LA in production vehicles.
Looks pretty good to me.
and 1967 Results, obviously using 273 in the v-8 Barracuda and Darts
Just one example of fuel milage comparisons from back in the day.
skep419
No show, all go!
Whenever overdrive gets brought up it reminds me of this thread back in the day.
Street / Strip(Overdrive) automatic trans choices ..
Big Squeeze "Honesty, if you're not an ET chaser and not after every last hundredth, I'd use a 3-speed Trans, 3.54-3.55 gears and a quality, loose converter and move on....having a low gear in the rear is WAY over rated especially with how well converters work now compared to 20-30 years ago..."
Sorry for dragging this thread even more off topic hahaha
Street / Strip(Overdrive) automatic trans choices ..
Big Squeeze "Honesty, if you're not an ET chaser and not after every last hundredth, I'd use a 3-speed Trans, 3.54-3.55 gears and a quality, loose converter and move on....having a low gear in the rear is WAY over rated especially with how well converters work now compared to 20-30 years ago..."
Sorry for dragging this thread even more off topic hahaha
Everyone has their own ideal build, but mine would include a good lockup converter, 3.55 or so gears, and a 500/518 OD. Why not have your cake and eat it?
In case I find a bag of money fallen off a brinks truck, I am also closely watching the ZF8 spd swaps and market for parts. If holley comes through and makes the terminator X stuff run the 8spd trans then game on.
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Because having your cake and eating it too would be not using worthless 3.55 gears with an OD. I'd consider 3.91s the absolute minumum. With 3.91s, your ratio in OD would be 2.69.
All depends on individual tastes and goals Rusty. I drove a lot of miles in my Challenger with a 340/non lock up 518 stock mopar hi stall converter/3.55 and loved the combo. I want to cruise 80 on the interstate and not go deaf. That combo would do it at about 2800 rpm. Not sure what I will go back with until I figure out the entire combo but 3.55 or 3.73 are likely.
Have at it and good luck!
Better compression on those motors back then and better gas. Wonder which had the biggest effect on mileage?
But they were also designed to run on 87 or less octane and meet emissions and there warranty. I don’t know how much extra a 10.5-1, 318 will do over what they did in ‘67, but it’s not worth the price of 91/93!
Since the compression was THERE, they HAD to have the gas to support it, so the two could not be separated.
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I agree! What is it we've seen Jim Laroy say time and again? The difference from one point of compression to the next is only about a 3% increase?
The less power the engine made the less % it was, the greater the power, the higher the % will be. While starting with a higher compression engine is great for hot rodding later, it isn’t a big gain and even more so on our earlier cars. Todays cars are in a different field.
Better heads or at least head flow is the key demonstration by @IQ52 AKA Jim LaRoy. On that note, it makes me wonder what the Chrysler engineers discovered when they tested the W2 heads on a 360. To bad it never was OK’d for the Little Red Express truck.
If the W2 actually flowed what the MP book and MP reported, that would have been an interesting engine to play with.
What higher compression would have delivered and quite well I think would have been a much snappier engine on he throttle.
The older 319’s were labeled at 9.0-1. I have one to take apart so maybe one day I’ll actually know when I mic it up.
It has been a while but I have had several of the early style 67-68 318's apart that had the different full floating rods and higher compression pistons. around 9 to 1 sounds right as they were much better than the run of the mill 70's/80's 318s.
A properly prepped 318 magnum with zero decked pistons and .035 or so quench would be close to ideal for mileage and would not require the use of premium fuel for regular street use. Probably wind up about 10 to 1.
@hotroddave has done several of these mileage type builds and has lots of info about them on moparts.com
@hotroddave, what say you?
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