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How fast 1940 series 50


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How fast is the engine turning at 50 (or 60) miles per hour in high gear on my 1940 series 50 with standard equipment?

I'm running 650 x 16 tires with nearly new tread. The speedometer is on the list to fix but working other issues first. I can almost keep up with freeway traffic but don't want to push it past 3.5 to 4 thousand rpms(hopefully I'm not allready doing that). Sometimes you just want to let the big dog run.

I'm also aware of the need for increased braking distance and keep double the distance I normally keep.

Thanks

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Depends on the rear axle ratio. The standard ratio for most of the 1940, 40 and 50 series cars was 4.40:1. This had the engine turning about 3300 rpm at 60 mph with standard tires, fairly high rpm for a long stroke straight eight although the engine was smooth and fairly quiet at that speed. Although these cars would go faster than 60 mph, the engines were noticably spinning at higher speeds. The optional 3.90:1 "high-speed" rear axle had the engine turning a bit under 3000 rpm at 60 mph. The 3.90:1 rear end was pretty popular in the western US.

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  • 1 month later...
  • 2 months later...

gary,

with 650x16 tires your rolling diameter is about 28.75".with a 4.4 ratio this would give you about 19.60 mph for every 1000 rpm.6o mph would compute to 3266 rpm.in high they will turn up to 4300 to 4400 max or 84 to 86 mph.a set of 3.9 gears will increase them to 90+.

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I have a 1940 56s and would love to have an overdrive on it. Does anybody know if somebody has tried to put an overdrive on a tourque tube car? There is a company stating that it should be possible. http://www.gearvendors.com/editorials.html

You have to cut the tourque tube and driveshaft and make some parts. There must be very many Buick owners willing to pay for an overdrive kit if it was available. Perhaps we could go together and ask Gearvendors if the could develop such a kit.

Jan

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There are several overdrive units available for the Model A Ford which also has a torque tube drive. So, I know that it is possible to install overdrive in a torque tube assembly. I suspect that it is a matter of checking around to locate someone who can do the machine work utilizing an existing overdrive unit. I doubt that you can purchase a ready made kit for a Buick; the demand is just not there.

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The 1940 50 series has a rear axle center section that will interchange with all the Buicks (except 80-90) up through 1955. The 53-55 V8 Dynaflow cars had 3,3-3.6 gears. I have a 3.4 in my 40 Super convert, and I drive it at 70-75 on the interstate where ever I go (I have driven it 100,000 mile +) Just remember that you need to stop it also. I installed the larger brakes from a Roadmaster, and that seems to keep me out of trouble.

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A question for "The Old Guy" Joe, or anyone who might know. Joe said that gears up to 1955 would fit in a '40 Series 50. rear end. Can I assume that this would also be true for a '41 Model 46? I have a friend who has just about had it with constant rebuilding of the Dynaflow in his 1955 Special and now that the back left cylinder has 20 lbs of compression he is leaning towards an engine, drivetrain swap. He dreams of finding a 401. Dream on. grin.gif

Since I have raised my hand to be first in line for anything that gets ripped out, would the '55 rear drive from torque tube ball back be interchangeable with what is presently in my '41? I was looking at the shop manual and a swaping of gears is probably beyond my level of compentency. Besides, there are probably not very many special tools J-1105 and J-1590 lying around.

Is it a safe bet that the present ratio in my compound carb '41 is 4.1:1 as per the manual? Thanks.

Unclefogey

John

BCA #41635

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, The center section from the 55 will fit in your 41 but you will probebly need to put the drive shaft and torque tube from the 41 on the 55 center section. You can measure them, but I don't think they are the same length.

If there have not been any changes, your 41 has the 4.1-1ratio

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