Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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#401742 01/15/18 10:29 AM
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You may want to skip this. It's the product of a scrambled mind. Is too.

Sitting here on yet another cold day thanks to canada, I got to thinking.

I've noticed the price of gasoline creeping up again. It makes me wonder if it is worth the expense of driving my 41 coupe around. Those old 216s with the 4"11 differentials could only get milage in the upper teens even on a good day, such as with a tailwind and downhill most of the way.

Now compare it with my 2011 GMC with a 6.2 liter engine and automatic transmission which gets about the same milage on regular.

Something is wrong here. Well, anyway it seems to be. Read on.

Why can't we do something that will make our old cars get better gasoline milage? Even if we go to a higher ratio differential, the milage will stay about the same owing to less efficient use of fuel. In other words there is a point where the trade off between gained in milage will drop off owing to stress on the engine to carry the load. You know.

Anyone got any insight as to why our old 207s and 216s are so danged inefficient. After all they only produce about 75-90 HP or so.

I'm thinking that I should adapt the transmission to a Honda Civic or Toyota Corona engine.

Gasoline at $2.30 a gallon is high for pouring through the guzzling old Carter.

What do you think?

Charlie computer

BTW: Telling me that your old 207 or 216 gets 25 MPH just won't be convincing. That kind of milage is a "pipe dream" and derived by inaccurate math and/or test. :Agrin

BTW2: Anyone know where I can get one of those things that went on the coil that made an engine jump up in RPMs at county fairs, etc. You older ones know what I'm talking about. I'll try anything.




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$2.30 a gallon? That's like 1985 prices again so drive even more! Jealous about that as we are over $4 gallon after converting dollars and we are still better than we were a few years ago (we hit $6 briefly when our buck was poor and oil was high).

You either need to make the 41 and its cargo lighter or make the drivetrain more efficient (motor,more gears,better axle ratio).

The neatest would be a small diesel engine swap. A 41 powered by a VW Rabbit! In Cuba I noticed many of the 50s taxis had small inline diesels transplanted into them. You can go with a smaller engine if diesel as they have high torque.

I have seen on Ebay the magnets that clamp to your fuel line that are suppose to improve your mileage. Maybe adding 2 or 3 of them would be even better.

But in any case you'd essentially be "rodding" the 41 which would be a steep price to pay when your fuel is such a bargain already...

Last edited by canadiantim; 01/15/18 11:24 AM.

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The two most important features that have improved gas mileage and emissions are fuel injection and the computer. Various things like oxygen sensors, etc. monitor the exhaust and adjust things like the timing and fuel air mixture for the most efficient use of gas. Regular fuel engines coften have a compression ratio of 11 to 1 or higher yest will not ping under load duet to knock sensors.
Then there is the transmission improvements like lock-up converters and overdrive ratios the allow you to cruise at 70 MPH at 2000 RPM.
All of this and small engies that can produce over 250 HP.

Chevrolets were always just average for gas mileage running in the 15-20 MPG range. Prhaps the best mileage ones were the overdrive equipped mid '50's ones that could get 20 to 24 mpg AT REASONABLE SPEEDS.

Last edited by Chev Nut; 01/15/18 11:33 AM.

Gene Schneider
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Tim,

The cost of gasoline is why you have such bad winters up there. That's so you will ot go out and waste any of it riding around, when you can, just to be going somewhere.

I can see why you have cabin fever what with nothing bur snow up to the top of your windows. Why you canada have enough to blow some of it all the way down here to NC.

I want to personnaly thank you from the bottom of my heart for the dusting we got a few days ago that thrilled the kiddies to no end owing to it causing schools being closed for several days. We close schools down here any time we hear the word "snow" even when the forcasters are ” Ã¥lking about there being some in and around Buffalo, NY. Do too.

Gene,

iagree

Charlie computer

Last edited by 41specialdeluxe; 01/15/18 12:30 PM.
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We blame all the cold weather on Alaska.

I do wish we could just head to a more southern US State without a ton of paperwork as it does get annoying dealing with the snow. Cold you can dress for but I'm getting tired of my spare time being consumed shovelling.

I literally need to go out and move some snow now...


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I put taller gears and a 5 speed with o/d in my 37 and it did not help the gas mileage,at first I think it made it worse but played with the jet and power valve spring and got it better but one would think that a six would do way better then it does. I think those motors were designed to run at the RPMs they do and thats it unless I done something wrong,I am about ready to see if I can get a carb from a newer six on it to see if that helps but I did get it where it can go 80 on the highway without sounding like its going to blow but no better gas mileage so far.


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Your gas mileage is dependent on several factors. One is obviously the RPMs. Another is the horsepower or torque required to maintain or reach the desired speed. If gearing reduces the RPM it may increase the applied HP and therefore not change the gas mileage. I will refrain from a technical discussion about throttle plate position et. al.


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Most that read these forums have seen the horsepower vs RPM curves. Each engine has one. Also, each engine has another curve which is horsepower per unit fuel plotted against RPM. And a vehicle has a "load" curve, which is the amount of horsepower required to push the vehicle at a given speed.

The maximum fuel economy will be where the above curves intersect. Simply lowering the RPM at a given vehicle speed may not improve the fuel economy is the RPM drops to the point where the point on the HP/unit fuel vs RPM is not in the range of economical use.

While I learned all this in college physics, I learned it first-hand in 1973 when the national speed limit dropped to 55 MPH. My then-modern import was delivering 39.3 MPG at 70. At 55, I could no longer pull hills in 5th (overdrive) gear, and on level interstate, the fuel economy dropped to 33.6 MPG. Needless to say I was NOT a happy camper with the new national speed limit.

Jon.


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"I've noticed the price of gasoline creeping up again. It makes me wonder if it is worth the expense of driving my 41 coupe around. Those old 216s with the 4"11 differentials could only get milage in the upper teens even on a good day, such as with a tailwind and downhill most of the way."

Charlie,

There are some variables that you can manipulate. You can easily change the rear gears to 3.55 using gears from a '50-'54 Powerglide car and you can optimize the carburetor jetting by experimenting with different metering rods and jets.

Have you looked into those things?

I put 3.55 gears in my '36 PU to lower RPM and also found new power and fuel economy with a '39-'40 Chevy W1 carburetor with '37 Chevy jetting (main jet and metering rod). It's now more powerful and uses less gas, in addition to being quieter and more pleasant to drive. The potential is there!

Ray W

brino #402142 01/22/18 02:05 PM
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Interesting discussion! Obviously the miserable intense cold weather in the Carolina's has given Charlie cabin fever. We are having a terrible cold spell here in Scottsdale. The days are not getting to 60 and the nights are just below 40!

As always, Gene's inputs are on target. The power density and efficiency in today's engines did not happen overnight. And there were some pretty rough spots along the way. Remember the impact of emission controls in the 70's. It was the mid 80's before manufacturers were able to start getting us out of that mess with respect to drive-ability, economy and performance.

I really appreciated the comments about the national speed limit and its impact. I had just purchased an new 1973 Chevy van with a 350 and Turbo-hydromatic 3 speed. It had a 3.07 rear. At 60 mph the engine was running just over 2400 rpm which was the torque peak for that engine. At 55 mph it was running 2250 and below the torque peak. Mileage dropped from 15 mpg to 12 mpg at the lower speed. You really had to open the throttle to maintain 55 on even the slightest grade.

As for the economics of the discussion, that really confuses me! I was so happy when I reached the point where I could drive my '37 everyday! Driving it is so much cheaper than working on it! Even if the mileage was doubled that means I would have spent $90 instead of $180 last summer to drive it every day for 1000 miles. Pretty cheap fun in my book!


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If you are serious about fuel economy, this link may (or may not) help:

http://www.thecarburetorshop.com/Troubleshooting.htm#Fueleconomy

Also, lots of pre-1950 Chevrolets had their original carburetors replaced with the (opinion) inferior Rochester type B. Remember, GM owned Rochester, and didn't own Carter. GM made more money by selling the Rochester.

Virtually everyone that we have talked to that have used both report a 15~20 percent increase in fuel economy with either the original Carter W-1 or the replacement Carter YF when compared to a Rochester B PLUS better driveability.

One other trick I don't necessarily recommend: during WWII and fuel rationing, farmers in central Missouri REMOVED the accelerator pump from the Carter W-1 carburetors. One has to feather the footfeed away from a stop sign, but fuel economy IS improved.

Jon.


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My 37 has a 57 truck 235 and I was told that around 59 the cam was changed for better torque at a lower rpm,my 57 motor has issues so I do have a 60 motor almost ready to go in and will see if it does any better on the gas mileage. Since those motors were designed to run with around 4.10 gears a cam with a different grind might be needed to get the motor to rum more efficient at lower RPMs and maybe the advance in the distributor tweeked some too. I did try a YF carb but could not get a stumble out of it so maybe time to see if I can fix it and see how it does.


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