I'd do the 283 because you have the proper driveline components to go with it. 4.10 gears- great leverage for the heavy truck, 5-speed manual trans- minimal loss in power to the rear end and 70% OD provides 2.87 final drive ratio. ( 80% would be better 3.28 final).
350 with the right cam, heads, and carb to match your driving and gear ratio can get you 20-21 mpg and have impressive power. Torque creates friction but also moves the weight of your truck. Find someone with an O-2 sensor to dial in your carb. 350 will be cheaper to build 327 will cost you. Vortec heads,ZZ4 cam 600 cfm carb roller block.
301-302 sounds great but if ya got to rev the piss out of it, gas mileage goes down quick. Any of the engines running efficently will get you 15-18 mpg on the highway if its a light truck. That OD is what will save you. Also how you drive it.
A lot of guys think that if you compare a smaller displacement engine to a larger one the smaller one will automatically get a lot better gas milage. Not necessarily so. When I was in the boating business people would buy a new boat with a V6 or a 305 in it because they felt it would give great gas milage and they didn't want to spend the extra couple hundred bucks on a 350. First time they would come in for scheduled maintenance half of them would****** and say they wish they had bought the 350. The smaller motors had to work so much harder to push the boat whereas the 350 would loaf along. I think you might find the same thing with a 283/305/307 vs a 350 in your truck. Trucks typically push a lot of air and also haul heavy loads at times, and those extra 50+ cubes really make a big difference. Don
301.6 ,I have one in my T rpu. I would go with the longer stroke 350 with an intake manifold with long runners and a mild cam with a 600 max.vacuum secondary carb.
some ramblings from.a mad man I think what's confusing is all of the different conversion factors. Proper air fuel ratio For gasoline fuel, the stoichiometric airfuel mixture is approximately 14.7; i.e. for every one gram of fuel, 14.7 grams of air We buy gas by the gallon and gauge its economic value by MPG , yet the calculation and requirements of fuel is based on pounds of fuel. Depending on the additives the fuel has in it the weight differs. Maybe I'll get into oxygenated compounds added, how they effect the weight of fuel yet throw the calculations off. Add some detergent and the weight changes the concentration of fuel in a gallon is decreased yet even more. We measure the air we need for our engines by cfm, yet the calculation is based on weight of air. So how much does one cubic feet of air weigh? No fair if you have to look it up. Now different temperature and different elevation air has different weights also. Pressure is not weight and the atmospheric pressure has a lot to do with how much air gets into your engine. Carburetors are rated in cfm. Did you know that this is also measured with a specific value of vacuum achievable. A 4 bbl is rated @ 1.5 inches of vacuum and 2 bbls are rated at 3.0 inches again another unit of measure that differs and prevents a logical comparison. We measure our engines in cubic inches of displacement yet dont include compression ratios. All 350s are not the same if you factor that in. And you could get the same power from a smaller engine. 350 with 8:1 would have a compressed value of 43 or 350:43 and a 350 with 10:1 would have a compressed value of 35 or 350:35. The 350:35 would produce more power even though the value has a lower number. Rpm is quite common yet some folks forget that it takes 2 rotations to equal one full displacement. So rpm /2 would give us our cubic inch per min displacement and then we need to somehow get to pound of air to figure the fuel we'll be using . Add some boost from a supercharger and things get different really fast. Horsepower is another one we use that really is a figment of calculation. You can't feel it ,see it , touch it, or hear it. Its based on torque measured at various rpms. Ist thrown around, lusted after, strived for put there's no logical comparison with out knowing or stating what the variables are. 300 HP at 2800 rpm is quite different than 300 HP at 7500 rpms yet its just 300 HP. There's no real magic involved because 1 pound of fuel = 19,000 BTU 1 gallon = 125,000 BTU 1 gallon = 6.1 lbs. Its how efficiently you transfer the energy that makes you faster, more economical . I certainly don't have an answer to the conversion and non comparable units of measure we use. Sure would be nice to have the stuff we deal with everyday be on an apples to apples comparison.
2 cents.... 305, quadrajet, advance kit the the distributor with a 15 vacuum advance can. good torque motor, 5 spd or 700r4 with 350 gears. Cam....rv or 305 HP.
2 cents. 283/th350 500cfm edelbroke, pertronix ignition, stock 55 Lincoln gears, 15-18mpg all day. I'm very fond of the 283 chevys, and the 302 fords.
This discussion of mpg remind me of my experience with my 64 SS Impala 327 buildup. When I got it, it was a stock 250 hp with a Powerglide and 3:08 rear gear. No matter how I drove it, it got a whoping 12 mpg. Flog it or baby it, 12 mpg. I wanted to have some fun with it, and the bottom end seemed to be fine. So I was a little (make that a lot) suprised that after a mild build up with camel back heads with 1.94 valves, a mild aftermarket rumpity rump cam (can't remember the brand or specs, but not too wild so I could still have vacuum for the power brakes), an Edelbrock Torquer intake,******* headers, 700 CFM Holley, a 350 Turbohydro and a 4:56 rear gear, it would still do 12 mpg no matter how I drove it. Go figure! Wish I hadn't wrecked it........never did get the 2000 rpm stall converter I'd still wanted to do. Damn! GGB
I like this combo, and small SBC's are a favorite of mine. The kicker with this guy using what he has is the 307 pistons are a bit expensive. They are kind of hard to find, and since he has a 283 block and a donor 327 crank he will need a new set of pistons to make it work. In this case, I vote for a 350 crate. Put old school valve covers on it and no one will know what it is! I think by the time you mess around with swapping parts and any machine work that might be needed you'll be money ahead.
yeah , rebuilds can be done a lot cheaper , and i'm sure you ended up with a good motor. if i have a motor apart i always bore and install new pistons. baked to clean and new cambearings/frost plugs installed. also , in the heads new valve guides, springs and hardened seats. then have it balanced. i want the motor like new so i have many years and trouble free miles of use. the last 283 i did i had about $800 at the machine shop
See that post above yours by burnout Nova ?. Those 307 pistons are expensive and a bore on that 307 block would have made the project completely nonsensical money wise. However, if you have it already and can use it, that makes more than perfect sense.
I do like the idea of doing a unusual SBC, but this time it doesn't seem to be the best route. I personally prefer a 302 (what I have in my Nova)... definately not meant for fuel mileage. But there's nothing cooler than a sbc 302 at 8,000 rpm!! Besides, if you want good fuel mileage, ride a moped!
In a 65 C10 just go with the damn Crate motor and keep the hood closed. Easy, cheap, fast, reliable whats not to like... (generic I know but it's a*****ing C10)
Actually mopeds are full , just like ...... Build for the highest amount of torque possible at the lowest "CFM" and gear the rest to optimize that accordingly will get you the best mileage possible.
You'd fool 99% of normal people at a car show. Maybe the guru's like ourselves that look at the block pad and front of the heads would catch on, but not most.
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