valk

'41 Roadmaster vs Century

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The late 30's early 40's Centurys are known for being the fastest American cars around due to the big engine coupled with the smaller body behind the cowl.  The wheelbases and hood lengths are identical. Selfishly, I'm curious where the Roadmaster coupe fits in. I would think the lighter Roadmaster coupe body would give the Century (at least the 4-door models) a run for its money. Any thoughts? 

Peter

 

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For the most part, performance should be extremely close, although in the late '30s, the Roadmaster was somewhat larger than the Century, hence the performance difference. They were quite similar in 1940 and identical in '41. Here's a chart I found a few years ago that was allegedly from the proving grounds illustrating the improvements that compound carburetion made in 1941.

 

903033494_Testtrackfigures2.jpg.6abf72f3

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Thanks Matt. According to the chart, 1941 Series 60 and 70 performance stats are identical. Move over Centurys, you share the stage with Roadmasters when it comes to performance, at least in 1941!

Peter 

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I was checking out the chart with some interest. The gas mileage numbers seem wildly inflated. Are they real? I don't know anyone who gets better than 13 mpg from a straight eight Buick. It would be great to learn how to get 15 mpg.

Apologies for getting off topic.

 

Dave

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My 1941 Limited pretty routinely pulls down 13-14 MPG on the highway at 60 MPH, so I don't think they're too far out of line with the numbers on the chart. At 45-50 MPH I think 16 MPG wouldn't be unreasonable. We recently took a long trip to Cincinnati and I made a point of checking how much gas I was putting in and how many miles we traveled and the end result was about 13.2 MPG overall for about 500 miles, most of which were at 60-65 on the highway. Not too shabby...

Edited by Matt Harwood (see edit history)
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That's pretty darn good, I'd say. I'm getting about 12-13 around town. What effect does dual carbs have? Intuitively I would think it would decrease gas mileage. Your experience?

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I actually think the dual carbs are unfairly blamed for being gas hogs. If you keep your foot out of it, you're only running on the front carb anyway. However, my car is running two front carbs on a synchronous linkage, not progressive, so they're running together all the time. Believe it or not, I suspect this improved fuel economy due to better fuel distribution. All eight cylinders are pulling their weight now and it requires less throttle. I've often noticed that the lightest changes in pressure on the accelerator make significant changes in speed, and at highway speeds, I bet I'm well under 1/4 throttle. This is all anecdotal so it's not evidence (I never paid much attention so I don't know what kind of mileage I was getting before the headers and carb upgrade), but our friend Jon (Carb King) has many times suggested that dual carbs working together will improve both performance and efficiency and I can't say he's wrong. That big car at those speeds with 4.20 gears gets acceptable mileage. Nevertheless, here's our Cincinnati trip:

 

944046529_20191018_1830571.thumb.jpg.927ebc40d43e53e904d6613e8c6972b7.jpg  1751524277_20191018_1830431.thumb.jpg.16aa267509fb5904ab3c048fea0e4bb0.jpg

 

1242439408_20191018_2044331.thumb.jpg.e359be0a8dbbf10089661929977cb5d4.jpg  33567510_20191018_2044151.thumb.jpg.d680b8f0e34f9390ce8b3ca3e2a51215.jpg

 

 

1663600467_20191020_1420041.thumb.jpg.adba75ab07ba967ee56c4123098f6fa8.jpg  1807630435_20191020_1420201.thumb.jpg.68cae0f0ae47d5a0f80555a970aa4e6e.jpg

 

Total of 475 miles and using 39.5 gallons of gas = 12 MPG. However, my speedometer reads about 10% low (when I'm at 60 MPH it shows ~54) so adding in that 10% (522 actual miles traveled) it it comes out to about 13.2 MPG.

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2 hours ago, Dave_B said:

I was checking out the chart with some interest. The gas mileage numbers seem wildly inflated. Are they real? I don't know anyone who gets better than 13 mpg from a straight eight Buick. It would be great to learn how to get 15 mpg.

Apologies for getting off topic.

 

Dave

 

 I do. Most don't like what I have done.  To Denver and back last year, around 1400 miles, better than 20 mpg. Measuring with a GPS speedometer.

 

  Ben

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Drove my well-worn ‘40 Century with 3.91 gears on a 5062-mile trip this year, mainly at 55mph or less, and averaged 13.2 mpg, with a single tank best around 16.

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5 hours ago, Ben Bruce aka First Born said:

 

 I do. Most don't like what I have done.  To Denver and back last year, around 1400 miles, better than 20 mpg. Measuring with a GPS speedometer.

 

  Ben

 

Okay, I'll bite.  What have you done and why don't people like it?  Are you running a different engine?   I get miserable mileage on my Super, but I really don't care because it runs like a top.

 

Neil

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10 hours ago, Matt Harwood said:

For the most part, performance should be extremely close, although in the late '30s, the Roadmaster was somewhat larger than the Century, hence the performance difference. They were quite similar in 1940 and identical in '41. Here's a chart I found a few years ago that was allegedly from the proving grounds illustrating the improvements that compound carburetion made in 1941.

 

903033494_Testtrackfigures2.jpg.6abf72f3

 

The most frightening part of that chart is the idea that my Super (with a 3.9 rear end) is capable of 101.5 mph!  I can't imagine doing that, but I guess they had young, adventurous drivers at the proving grounds!

 

Neil

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28 minutes ago, neil morse said:

 

Okay, I'll bite.  What have you done and why don't people like it?  Are you running a different engine?   I get miserable mileage on my Super, but I really don't care because it runs like a top.

 

Neil

 

 Bored, hi comp pistons, Throttle body Fuel Injection, 3.36/1 gears.

 

  Ben

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Okay, thanks for your answer.  Anything you do with your own car is fine with me.

 

Neil

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7 hours ago, neil morse said:

Okay, thanks for your answer.  Anything you do with your own car is fine with me.

 

Neil

 

 Thanks, Neil. I am of the same opinion.  I love your car.

 

  The things I have done sure are not cost effective.  Not to save fuel, anyway.  I did not do them for fuel savings, but for driveability. I drive the car more than most. The fuel savings is a bonus.

 

  Ben

Edited by Ben Bruce aka First Born (see edit history)
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14 hours ago, Ben Bruce aka First Born said:

 

 I do. Most don't like what I have done.  To Denver and back last year, around 1400 miles, better than 20 mpg. Measuring with a GPS speedometer.

 

  Ben

 

Ben, if you're having fun in your car, I don't care if you put a nuclear reactor under the hood. It's awesome. Drive it!

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Matt, any chance of getting a pic of your carb set-up? I'm intriqued by your 2-carb set-up and the linkage that has both carbs operating simulatiously. 

Peter

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2 hours ago, valk said:

Matt, any chance of getting a pic of your carb set-up? I'm intrigued by your 2-carb set-up and the linkage that has both carbs operating simultaneously. 

Peter

 

Matt, me too, please post some pictures of your throttle linkage.

Dave

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On 10/30/2019 at 10:37 PM, Rod Frazier said:

Drove my well-worn ‘40 Century with 3.91 gears on a 5062-mile trip this year, mainly at 55mph or less, and averaged 13.2 mpg, with a single tank best around 16.

 

 5062??   You have left me in the DUST!  I need to get busy.

 

  If you do that often a 3.36 from a '55 century will pay for itself quickly.

 

  Ben

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I wish I could take credit for the setup I'm currently running, but our mutual friend @Lawrence Helfand did most of the legwork on the synchronous carburetor setup for his '41 Century. Yes, I'm sure it's been done before thousands of times over the past 80 years, but he found the right linkage pieces at Summit Racing and it all literally bolts right on. You'll need two front carbs, of course, and I did make both chokes functional on my car which is probably part of why it starts instantly and idles well hot or cold. I did notice improved throttle response, it's smoother at all speeds, and there may be a bit more power, but it's hard to be certain in something like this and I also added headers and an oversized exhaust system at the same time. Nevertheless, I am very pleased with the upgrade and would not go back to the stock setup. The look is subtle enough that most people won't notice and I've been looking around at used vintage throttle linkages thinking I could make something that looked almost OEM in place of the modern heim joints. But given that my car isn't a show piece, I'm not really concerned about it and am happy with it as-is (I obviously saved all the original parts). Hopefully Lawrence will chime in as well, since he's actually the trailblazer here. I merely stood on his shoulders.

 

There are a few photos below but you can get all the details in my Buick Limited thread where I went through everything step-by-step:

 

 

Linkage8.thumb.jpg.17e59994f3ed7a0c465a32997d712ed7.jpg  Linkage6.thumb.jpg.767213f96852f4443a5bf7bf3325790e.jpg  Linkage4.thumb.jpg.3261f62f9b80e0dffb22cf7f98179179.jpg  6-7-19-1.thumb.jpg.3e1c5f60aeb8afe3d0bc0a10cc799300.jpg

 

6-7-19-2.thumb.jpg.9c2b05196abbb8fa8184aa3eac156295.jpg

 

I believe this is the linkage Lawrence and I used. You'll need two, and the one between the carbs will need to be cut to length and re-tapped on one end to accept the heim joint. Be sure to cut the correct end, since one end is reverse-threaded so the overall length can be adjusted simply by turning the rod itself (this is how I was able to get both carbs synchronized properly). I seem to recall that threads are 1/4-28. The longer rod from the pedal to the front carb just barely works as-is. It's 33 inches long and that's exactly how long you need with enough threads in the rod to be secure.

 

https://www.summitracing.com/parts/aaf-all54158/overview/

 

Hope this helps!

 

 

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It certainly does, thank you. I'll study this carefully. Wish my exhaust manifold and headers were as nice as yours...

Peter

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Ben:  What's involved in that '55 Century rear end swap?  Complete axle?  Pumpkin?  Just the internals?  I've been looking for a rear end with the 3.61 gears, but your idea sounds even better.  Not that I want to cruise that much faster, but sometimes you have to get on the Interstate and it's good not be in other people's way!

 

 

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On 10/30/2019 at 8:37 PM, Rod Frazier said:

Drove my well-worn ‘40 Century with 3.91 gears on a 5062-mile trip this year, mainly at 55mph or less, and averaged 13.2 mpg, with a single tank best around 16.

 

I would be very interested in hearing more about this, and especially if it was in the US (or Canada). Have you located long stretches of highway that are relaxed at those speeds?

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24 minutes ago, Bloo said:

 

I would be very interested in hearing more about this, and especially if it was in the US (or Canada). Have you located long stretches of highway that are relaxed at those speeds?

I drove from Utah to South Carolina and back, mainly on secondary roads, to attend the Glidden Tour in Rock Hill.  I probably drove about 200 miles on interstate highways, but quite a bit on US highways.  Here in Utah the speed limit on the interstate is 80, but it was generally about 60 or 65 in the southeast, and usually the US highways were 55.  Mostly I used the Google Maps navigation system, and it only got me lost a couple of times, though often I had little idea of exactly what routes I was on at any particular time.  I averaged a little over 300 miles/day and tried to stop early to have time to explore the area and get a little exercise.  The Buick was a pleasure to drive and the only mishap was the wiper mechanism either breaking or coming loose in a rain storm in Oklahoma.  Bought and applied some RainX at a truck stop and soldiered on.  I think I'll go back for the Chrome Glidden Tour next year in Tennessee. 

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6 hours ago, Matt Harwood said:

I wish I could take credit for the setup I'm currently running, but our mutual friend @Lawrence Helfand did most of the legwork on the synchronous carburetor setup for his '41 Century. Yes, I'm sure it's been done before thousands of times over the past 80 years, but he found the right linkage pieces at Summit Racing and it all literally bolts right on. You'll need two front carbs, of course, and I did make both chokes functional on my car which is probably part of why it starts instantly and idles well hot or cold. I did notice improved throttle response, it's smoother at all speeds, and there may be a bit more power, but it's hard to be certain in something like this and I also added headers and an oversized exhaust system at the same time. Nevertheless, I am very pleased with the upgrade and would not go back to the stock setup. The look is subtle enough that most people won't notice and I've been looking around at used vintage throttle linkages thinking I could make something that looked almost OEM in place of the modern heim joints. But given that my car isn't a show piece, I'm not really concerned about it and am happy with it as-is (I obviously saved all the original parts). Hopefully Lawrence will chime in as well, since he's actually the trailblazer here. I merely stood on his shoulders.

 

There are a few photos below but you can get all the details in my Buick Limited thread where I went through everything step-by-step:

 

 

Linkage8.thumb.jpg.17e59994f3ed7a0c465a32997d712ed7.jpg  Linkage6.thumb.jpg.767213f96852f4443a5bf7bf3325790e.jpg  Linkage4.thumb.jpg.3261f62f9b80e0dffb22cf7f98179179.jpg  6-7-19-1.thumb.jpg.3e1c5f60aeb8afe3d0bc0a10cc799300.jpg

 

6-7-19-2.thumb.jpg.9c2b05196abbb8fa8184aa3eac156295.jpg

 

I believe this is the linkage Lawrence and I used. You'll need two, and the one between the carbs will need to be cut to length and re-tapped on one end to accept the heim joint. Be sure to cut the correct end, since one end is reverse-threaded so the overall length can be adjusted simply by turning the rod itself (this is how I was able to get both carbs synchronized properly). I seem to recall that threads are 1/4-28. The longer rod from the pedal to the front carb just barely works as-is. It's 33 inches long and that's exactly how long you need with enough threads in the rod to be secure.

 

https://www.summitracing.com/parts/aaf-all54158/overview/

 

Hope this helps!

 

 

My experience with the duel front carbs and parallel linkage pretty much reflects what Matt has said about this modification. It simply works better and runs smoother but I recently decided to swap my 320 motor Stromberg AV 16's for a pair of Carter 528S which is the front carb for the 248 motor. My plug color was a dark cocoa brown that was really pretty good but I reasoned that a pair of smaller carbs might be even better and I have come to understand that the Carters metered fuel better then the Strombergs. The result is another improvement in smoothness and throttle response especially off idle. Starting was already very good with the Strombergs but the Carters are a little better especially after car has sat for a few weeks. Also found the Float valve on the Carter handles the auxiliary electric pump better as the Strombergs would overflow even though I use a low pressure pump.  I have not checked mileage or plug color yet. It is now a bit less sensitive to throttle input which I feel is a result of leaner and more accurate delivery. Idle and exhaust note is a very steady beat without hiccups. I detect no loss of power or acceleration with the Carters. I have a Gear vendors overdrive and easily cruise along at 70/75. Pulling out from that speed to pass is impressive and I suspect car guys think I have a V8 swap under the hood. The only thing to make it better would be a duel exhaust for better breathing and increased intake velocity.  This modification is very easy to do with the Summit linkage kit which works better then the stock hook end rods. About a 2 hour job.  

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Damn, that set up looks good in many ways. How/where did you guys hook up the choke heat tube on the second carb? 

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