Here's the deal. My next project is a '46 Chevy Stylemaster two door sedan. You guys suggest the mods, I build it this winter, and we see if we can achieve 30mpg. I want you to know first off that my last string of project cars did get built to completion, and that I sold off some of my future projects, in order to build this car, so it will get built. Plus since it's already a runner, it's just a matter of doing the mods and testing the results. So I want to achieve 30 mpg (or at least see how close I can get) with my '46 AND it's gonna run a '61 235. It's already in the car and it ain't coming out. An old timer told me he got 32 mpg from a '53 Ford with a 6/stick/OD, so I think it's entirely possible. My 318/Torqflite '60 Fury battle cruiser gets 24, I think this is doable. What kind of mods am I looking for? Like I said, it's going to run the 235, and I'm not made out of money, so no super exotic fuel injections or anything like that. I know a lot of you guys know how to make power out of these old motors, how about making efficiency out of them? This is going to be a fender skirted lowrider, so there's no need to be drag racer fast. Just needs to do a comfortable 55mph and get the mileage. My first thoughts are (feel free to comment) a free-flowing exhaust, possibly dual, an electric fan to replace the belt-driven mechanical one, generator replaced with a newer alternator, stock single carb with a bug screen replacing the air filter, some kind of overdrive (the expensive part, anyone got some options here?) rear end gears, an HEI maybe? Let me know what you guys think. What are the mods to make and what should be avoided. Do you think it can be done?
I think the only way to get 30 is to cut it down to 2/3 size and put a little 4 popper in it.... but you might be able to get decent highway mileage on the flats with a long rearend gear and overdrive. Probably have to go open driveline to do it. And not much need for free flowing exhaust if the idea is to keep rpm down and the throttle closed, if you're not burning much fuel you're not making much exhaust. the old fans they had back then don't move much air, so they don't take much energy to spin.
You might want to look at swapping a 4 or 5 cog box into it too....with the right rear end ratio's you will get better performance and MPG.
I think it might be do-able. If not, you might get close. I read an article about a guy that had a '65 Plymouth Valiant with a slant 6 in it. He got tired of the 3 on-the-tree, so he decided to research what he could do to boost hi-way speed without killing his gas mileage. He ended up adapting a 5 speed overdrive ****** out of an '82 Mustang. He went on to say that with 5 people in the car they could do 75 comfortably and get 30-31 MPG. He was running 3:23 gears in the rear end, and 235 60 14 BFG tires in the rear. Sounds like a neat thing to do to a 6 cylinder car that might be a little pokey. You could probably do something similar in your Chevy. Maybe run a 5 speed out of an S-10, and some tall tires might help. More than likely, you won't be riding 5 deep, but the Chevies weight might make up the difference. A guy I knew had a '46 Chevy 2 door sedan with a full oiler converted 216. He was running a Tattersfield dual 1 barrel intake, Fenton headers and two stock one barrels that were jetted down some. He said the car averaged about 24 MPG around town, and about 28 on the freeway. Pretty good considering we live up here at over 5200 feet. Sounds like a great plan. Keep us posted on your progress! E
Okay- Here's the plan. Clean up the ports, and the chambers. There are several well-written articles on how to best accomplish this with the Six, and probably even with the exact head you've got. Shoot for 9.75:1 compression through milling the head and running a good flat-top piston. Get a cam with relatively mild specs (I'd suggest around .480 lift/280 degrees advertised duration, 110 lobe sep.). Have the pistons, ports, chambers, valves, and springs coated by Calico Coatings. Run a windage tray to strip oil from the crank. Run a good oil pump pickup and oil pump. It doesn't have to be high pressure or high volume, it just has to be built right and clearanced correctly. Get a good water pump- high efficiency, please. Run a tri-power setup with progressive linkage so you're running on the center 2-bbl. carb first, with the end carbs kicking in at about half throttle onward. Get a good high energy electonic ignition system with an MSD or similar box. Run a good long-tube header or headers. If you can get tri-Ys, all the better. Don't get huge 1.750-inch diameter primary pipes either...1.5 is fine for this build. Get them coated regardless of design. Back this motor with a 700/R-4 or 200/4-R non-computer controlled automatic overdrive trans. Run 3.55:1 or 3.73:1 rear gears. The engine will almost idle down the freeway and knock down some solid numbers for you on the long haul. Getting up to speed won't be a problem either, as the gearing and engine mods will offer good midrange - especially when all three carbs are opened up! This will impact mileage...LOL... But, if you want a good, solid, reliable package capable of knocking down a solid freeway economy number, this would be a good plan. EFI would be even better...but this could work real well... ...and I promise it'll do it on 87-octane...!! Scotch~!
I got 28 mpg in my fairlane last week on a 300 mile drive. stock motor with 7.5:1, 5200 holley weber carb, factory electronic ignition, T5, 3.50 gear and some 245/45/17's granted I have my timing dialed back right now which is helping out alot and the stock 4cyl jetting in the carb
Agree with Scotch, mostly, but I think a better choice of carbs will help. I am using Holley-Weber 2 stage 2 bbl's on my straight six. Two of'em. If you're shooting for mileage, go with one. It's a 2 bble, but runs on a single, until you stomp on it, then the second bble kicks in, like half a four barrel. Should be very efficient if you keep your foot out of it. Run it slightly lean, and use a REAL good ignition. Open up plug gaps to 0.45". If you go into rebuilding the engien, try to lighten up any reciprocating parts as much as possible, rods, pistons, even the crank. An aluminum flywheel may help, with your 5 speed.
How about reducing weight? If this is going to be a kustom, better use bondo instead of lead! Replace some steel with fibergl***. Put the bumpers in the garage until fuel prices come down. Replace them with a simple tube bumper or nerf bars. Radials tires on aluminum wheels. If it has carpets, pull them out. Those old carpets and padding could get pretty heavy. This all might buy you 1-2 mpg or so, but if you are shooting for 30 mpg, every little bit counts.
I think you can get to 30 mpg highway with the right drivetrain. My wife's 98 Bonnevile is a big car and gets that easily with the AC on at 80 mph. It weighs about 3600-3700 lbs? I think. I'd suggest you might rethink using that 235 if this is a hood-shut daily driver kind of car. Find one of these very efficient (and cheap) late model SEFI 3.8 Buick/Olds/Pontiac and a 4L60 transmission. There are combinations that will adapt it easily to RWD. A free flowing exhaust, radial tires, and a rear gear no lower than 3.00 should do it. Try to keep the weight down and lower it for best possible aerodynamics. If you really have to keep the 235, get the compression up as high as octane allows, maybe 9.0 - 9.5:1 for regular. Get some good quench area by zero decking the block, do a little pocket porting on the head to let it flow a little better, esp on the exhaust side. Electronic ignition is a must. Cold air intake to the carb for best air density. Electric fan will get you a couple of horses and build some mpg. OD transmission is a got-to-have for that 30 mpg goal. You may need to convert to alternator. At cruise with OD the engine may not be turning fast enough for a vintage generator of produce enough current for lights, etc. It looks out of place on a vintage engine, but a Weber 2bbl is going to be more efficient than a vintage 1bbl rochester. A manual trans would be better than an auto. If you aren't racing, maybe even one of those 70's three speed + OD transmissions would work.
Go over to stovebolt.com to check out what to do with the 235, if this is just for milage and not power, use a manifold heater on the intake to atomize the fuel better. Some stock manifolds are already setup like this, I have one for a 235. The one barrel intake and exhaust are connected together. It's an old trick to get those old carbs running smoother. Pretty sure you get better milage, but it kills the performance. Make sure the engine is in good tune and put in a new oil filter instead of the bee hive (or like mine NO filter at all!). If you can adapt an over drive all the better. If you DON't go the 235 route I think a modern 4-banger like GM's ecotech would be a cool alternative. Good milage out of the box and some performance parts are coming online. The thing with those little 4-bangers, alot of the upgrades also increase milage. You won't blow the doors off of anybody, but it will run better than a single barrel 235!
A friend of mine had a 235 six in a 61 Chevy pu with two one bbls on a clifford intake, fenton headers, small cam with a 3 spd with od. On several trips he would average around 26-28mpg. Once you put it in od, the motor was just above 1500rpms and no strain on the motor.
Just had a brainstorm!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! If you dig the Inlines....how about running one of those new all aluminum straight sixes that come in the Olds Bravado, and other new vehicles? With the computer controls, fuel injection, and all, it should get better than 30 MPG. Wonder how one of them sound without catalysts, and with a set of Splits with Brockman Mellowtones on it? HMMMMMMMMM, may need a new project to find out......
I think there are some good advice here, but your engine is most efficent at peak torque. Because an engine is just a big air pump, you want it pumping the least air it can while making the power you need. This means lower rpm while still being close to peak torque on the highway. Here is what I would do in my quest for milage. I think you will find I mirror some others comments. Run as much compression as you can get away with. Reduce pumping losses as much as possible Oil control is your friend Run a camshaft that makes peak torque low in the RPM range Gear it with some shorter gears to get the car moving easily Run an overdrive transmission so that you are below peak torque on the highway. With a good modern cylinder head, you can get about 12:1 compression with a streetable cam like you would need. But this is an alluminum head with a modern heart shaped chamber, with all the coatings you cam think of. the BSFC of the a motor like this is usually in the neighborhood of 0.32-0.35. Pull the head and measure the piston/deck clearance. You want as little as possible, and zero is best. Run a gasket in the neighborhood of 40 thou for a tight quench. Polish the chamber to remove any sharp edges which could heat up and cause detonation, and make sure they are mirror smooth. This will keep the carbon from sticking and compression creep from happening. Equalizing them in volume is good. I would shoot for 10:1 with your motor, if you can get good quench, and ceramic coat the chambers, piston tops, and exhaust port/ valve face. Make sure there is a 3 angle or better valve job. You need a narrower face to make sure the valve seals when it closes, but a wider face to transfer heat. I would also go for a 30 degree valve seat angle instead of the more common 45. Run a dual pattern cam with a wide lobe seperation and short fast ramps. We want to trap as much cylinder pressure as possible. Look for a mild cam. About 200ish duration at 50 on the intake with another 5-10 degrees on the exhaust with a 114 lobe seperation. Run it about 5 degrees advanced. Lift is not that important in an application like this. Plus stiffer springs needed for more lift increase friction and pumping losses. Run a windage tray, crank s****er, and std volume oil pump. Run the thinnest synthetic oil you can get away with and still have good oil pressure. You might need an oil cooler to do this. Run an electric fan, modern small car alternator, and a good water pump with a small impeller. Run a small single 2 brl or single 1 brl carburator that is jetted a lean on the part throttle circut. Don't lean out the idle or it will be hard to start and keep running when cold. Also down lean out the power circuit or you will hurt the motor. Throttle response will be phenominal with a 270cfm 1 barrel. Run a hot ignition to ignite the lean mix. Run as much timing as the engine wants at full throttle. Make sure you run the va***n advace, and run as much va***n timing as the engine will tolerate. The carb fuel and ignition curve is the most important part and getting good gas milage. At part throttle cruising, you can go real lean (18:1 or more) with tons of timing because there is very little load. This is what will give you good highway milage. Get long tube headers. 1.5" with the longest tube length you can find. 3/2 or 6-1 are pretty much the same. The 3/2 try Y's are the best for low rpm scavenging which is what you want. Coat them to keep the heat in and so they don't rot out on your. Run a BIG radiator and keep coolant temp between 160 and 180 degrees. You want to make sure the combustion chamber stays cool to kill detonation, so the closer to 165 you can keep it, the better. Keeping the engine cool will also let you use a thinner oil and maintain oil pressure. Run a stick shift with a deep 1st gear to get the heavy car moving, and an overdrive. Gear the car with as much gear as possible, but still have the engine ticking over at 1800-2000 rpm in overdrive at about 70mph This motor is all bottom end and midrange, and will be all done by 4500rpm. This is a torque monster that should peak about 2500rpm, with a HP peak of about 3500rpm. I think this should go over 30mpg in a 3500lb car with no real problems.
Wow, you guys really stepped up with some good advice here. Not only will this motor show some good MPG numbers, but it'll look nice and make more power too, so I think it's very do-able. Here's the plan so far, and some questions. Definitely going with the 235. Fuel injection scares me and I really don't see any of those cars pulling down 30MPG. Head porting-cleanup and a good three angle valve job are a must, with hardened seats to run non-leaded gas, plus a mill job to add a bit of compression and keep everything square. The windage tray sounds like a good idea, I'll have to find one. Dual exhaust with a split header would be fun, I'm definitely going to a modern alternator, which should be easier to turn and provide more amps, switch to an electric fan and the best water pump I can find. A big radiator is very do-able also, cool motors run the best. A single or dual Weber carb setup sounds do-able too. My questions are, why radial tires? Will those really do anything for my mileage? Do I really need a different cam? I figured the one that's in there is probably pretty mild the way it is. And lastly, I already have an HEI laying around from a '72ish 250 I-6. Can I use that in my 235? Or is there a good electronic ignition availible for the stovebolt? This should be an interesting project, and shouldn't be too terribly expensive to build, either. I'll keep everyone updated as I get started, and I'll check out the stovebolt website too for tips. First step is a new wiring harness, then I'll go from there.
Yeah, radial tires produce less rolling resistance than bias ply tires. You give up "the look" but you gain a couple of points on the MPG meter. Another tip might be to use synthetic oils and grease for less friction in the engine. If you have drums, and you can live with a little extra travel, you can back those off a little for slightly less drag. Moon hubcaps?
Thanks, that was the info I was looking for. Now I need to figure out what kind of ****** to use in here, or if there was ever an overdrive that mated up to the old 3 speed? It's gotta stay a stick, 5 speed or an overdrive on the old 3. Anyone got any ideas?
go with a stick 5spd, better then auto ******. id think that a modern 5spd woudl be better then your 3 speed even if it has overdrive... danny
Well - thinking outside the box on the ignition side - I've done this on my flattie, and will be building it for my 235 when I put it in the 51. It definitely makes a difference, http://pic***o.org/mjlj/ my trial run lashed up installation http://pic***o.org/mjlj/?q=node/492
chop the top and lower it. get it out of the wind. dump the frt bumper and build a chin spoiler. a/c or run with the windows up, too.
How about using a couple of SU carbs - you'll find them in most British cars of the 60's, 70's and 80's as well as the Datsun/Nissan Z cars. SU carbs give excellent economy because of their constant velocity design and they are so easy to fit and tune to almost any engine. Here's one on my Citroen. They look very cool and old timey - especially when the dashpot is polished.
While a modern alternator with proper bearings instead of bushings & a smaller m*** to turn is more efficient from a rotational loss perspective, your parasitic HP loss from running electric items like fans & water pumps will still be offset by the increased HP required to turn the alternator/generator to produce these. There is no free lunch. Unfortunately, there's no easy way for most average folks like us to figure out how much HP a mechanical fan takes to turn & how much increased paras***ic loss due to alternator/generator output it takes to run an electric fan (or water pump) to accurately compare the two. I would offer this though - your electric fan runs full speed all the time it's on. A mechanical flex fan with a good clutch will only turn when needed. A mechanical fan, even when engaged with the clutch, will only turn as fast as your pulley ratios & engine speed combination requires. A good shroud will increase the efficiency & you can run a smaller fan. Yes, you can put a thermostatic switch on your electric fan & I recommend it if you choose this route. The reason racers use electric this & electric that to reduce parasitic HP losses is because most of them are running total loss electrical systems for short periods of time. They're not having to turn a generator to make that power, so it "feels" free - it ain't (they pay for it with electricity from somewhere else). Herein also lies the fallacy of electric/hybrid cars being clean - that electricity is made somewhere - might be a coal-fired plant spewing some of the worst type of pollution into the air. There is no free luch. It takes power to make electricity & the more juice you demand from your alternator/generator, the harder it is to turn & the more HP it robs from your engine. W/O accurate data, I'd guess that a well-engineered mechanical fan system would take less HP to run & be more efficient. True, cool engines produce more power, but hot running engines produce better fuel economy. You can run an engine too cool as well. It has to do with air density too - hotter air is less dense & requires less fuel to achieve the proper air:fuel ratio. EFI takes all this into account, as do carbs to a certain extent. Smokey Yunick was working on a hot-air engine years ago & was getting good power & amazing fuel economy out of his early experiments. Controlling detonation is the challenge here. Chrysler tried a similar, but somewhat less successful experiment with their lean burn systems of the '70s - computers & EFI put paid to that though. Overall, I think this is a cool project & I commend you on your efforts - if it were me, here's what I'd do: I think you want compression, good ignition, & efficient carburetion - that last bit will be your challenge. The proper gear ratios & a manual trans are steps in the right direction too - I'd go T5 or, if you must have an auto, 200R-4 (less parasitic losses than 700R-4 & cheaper too). I'd run gears in the 3.00-3.25 range & find a T5 with a 3.76 first gear ratio - should provide pretty good acceleration, good ratios, & a nice O/D ratio.
flet ernie, the electric fans don't run all the time and generally not at all going down the hiway. THAT's where they get better milage, well, that and they can make the engine run at a hotter temp(consistantly.good for milage AND engine wear)
You wanna WHAT??? Make a ****bolt motor get good gas mileage??? Ha...first I'd worry about getting one to run for more than like five minutes without self destructing, but ***uming you have one of the rare ones that can hold itself together for harrowing trips up to 40mph, there ARE some things you can do to improve it's efficiency. Since I may just HAVE to dump a ****bolt into my 52 if nobody wants it as-is, I've already planned out some stratagies for making it get good mileage. (With "good" for these engines in old heaps with three speed ******s and 4.10 axles being maybe 10mpg!). My first mod would be the carb. The old one barrel ain't gonna cut it. You need to buy (yes, a novel concept) an intake that will either accept a larger 2v or a single 4v carb, then make a carb adapter to bolt on a Rochester Vara-Jet 2v carb...the pre-feedback model found on 1980-82 Chevy 2.8 V6 engines. These carbs cost a fortune to rebuild (why I took the freshly rebuilt one off my 49 before getting rid of the car), but they are extremely efficient staged two barrel carbs with a small primary and a larger secondary circuit. Being calibrated for a 173 cube motor will put them a little lean by 216 or 235 standards, but not so much as you'll notice it anywhere but in the way it gets better mileage. You will NOT find a carburetor that works better, or delivers such smooth and crisp throttle response and driveability. Ain't cheap, but damn well WORTH it! Next up, a Pertronix electronic ignition conversion for the stock distributor. You also want a good coil and the vacuum advance working right and hooked to a manifold vacuum source. A split exhaust would help a little, but isn't neccessary. I'll just stick a full single under my car if I have to put a motor in it, the miniscule difference it MIGHT make in mileage isn't worth the staggering cost that a split manifold and duals would add to the project. You always have to evaluate whether or not a given mod is WORTH it's cost and effort in it's expected return. Next up, an internally regualted GM alternator and full 12v wiring. Then ditch the mechanical fan, install a 195 degree thermostat and run an electric fan. Tune the motor well and you SHOULD get better than stock mileage by a long shot. Probably in the 10-15mpg range. Of course, installing a three-series rear axle ratio with a 2.8 V6 and an auto trans will get you an honest-to-goodness 30mpg over the road...but don't be a ****ing idiot...**** like that will never be COOL. Stick to the ugly, prehistoric ****bolt and just pray it holds together long enough for you to actually burn a full tank of gas and check it's fuel consumption.
My first thoughts were tires and weight reduction. Somebody said to run AC and keep the windows rolled up. I think that's a myth. As a matter of fact, I think Mythbusters busted that myth on TV the other day. Electric accessories are definitely more efficient. Yes, the electrical power has to come from somewhere, it's not free. But transmission of electrical power is much more efficient than mechanical transmission. Friction is your enemy. Maybe you want some good wheel bearings and such to further battle friction. Fuel injection would seem like a good idea. A modern powertrain would seem like a good idea. And as I've said before, a diesel burning waste vegetable oil is the cheapest thing on the road today. And it smells like fries. I'm thinking the chop or similar aero enhancements would be of greater use at higher speeds. If you're cruising slow, it might not help too much.
A good clutch on a fan doesn't cost anything on the highway either. If y'all are dead set on electric accessories, get the smallest, most efficient fan you can get away with - compare amperage ratings... Wish I was a math/engineering major instead of a state-educated criminology major - I could prove some of this with a bit of math! I don't think the difference is that great, to be honest, but I think a well engineered mechanical setup is more efficient.
Well, I was actually searching the web for generator info & stumbled on this guy's pages. He's got loads of cool pages here, well worth browsing through. The kicker though, was he agrees with me that a clutch fan setup is more efficient than an electric fan setup. Also like me, he doesn't really back it up in any way other than to just say it! Check out the link, then navigate to his other pages - some good info here. http://www.rowand.net/Shop/Tech/ThermostaticClutchFan.htm
Thats what i kind of dig about kustoms in this day and age, you dont need a cool motor to have a cool custom, however more often than not you need a cool motor to have a cool hot rod.
I haven't been running any fan for 4 years now. granted I have a radaitor rated for a 400hp small block on my 60hp six. only overheats I have had were when I left it on high idle warming up while talking to some buds one night....and kinda shot the **** for 30 mins..... and the other was 100 degree weather on the 4th of july weekend stuck on the interestate in traffic (5 mile backup moving at 2 mph) other than that as long as I am moving about 20 mph it will stay cool. I would go with the 5200 holley/weber carb. TONS of them out there.....cheap....easy to mess with. mine un jetted off a 75 pinto gave me 28mpg last weekend. I would skip the pertonix and focus on a better distributor that had a mechanical advance and a vacuum advance in it.....maybe guts from a modern distributor in a older body? def lower it and shave that puppy to make it slicker in the air....that will help tons. and the cheapest thing would be to drive it easy and slow. drag really goes up over 55mph I would run a stock sized valve but clean up the head as best you can. higher compression will get better milage. stock cam but run headers
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