Putzing with 1941-42 dual carb parts

[Guest]

Did some cleaning/refurbishing today of the dampers used under rear carb on dual carb systems. Interesting find. Three different metals used for butterfly shaft. Looks as though Buick started with brass then WWII started and I found two with steel shafts and one strangely enuff with a copper shaft. Maybe visible in photo.

Edited May 12, 2019 by Guest (see edit history)

[Guest]

Later models evolved with a thermostatically controlled switch that stops it from opening till engine warms sufficiantly to accept the extra mixture. There also appears to be an update designed to help avoid having the counter weight hang up and not close from full open. Merely a pin used as a stop to limit travel to a bit less than full open.

Edited May 12, 2019 by Guest (see edit history)

[Lawrence Helfand]

Removed my shaft and butterfly plugged holes and replaced rear carb with another front. Adjusted accelerator pump linkage to least throw and installed a parallel linkage from a Summit aftermarket kit. Also importantly hooked up rear carb choke. What a difference in the way the car runs now. More responsive and smoother running especially at idle where it always shook a little. Gas mileage is actually improved and power is increased throughout the powerband. Engine now has a more even mixture in all cylinders. Also pinned my heat riser flaps open to cool down manifold heat and swapped fans for a Summit which moves a lot more air at idle. Best improvements I ever made to the motor along with Petronix pickups flame thrower coil and advancing timing way past factory setting which was for the low octane fuel of the period improving gas mileage and cooling. Just had a Gear Vendors overdrive install done and the results are wonderful to say the least. All of these modifications are reversible and make the driving experience match the hidden potential of my 41 Century. 

[Guest]

Thanks for the input! I'm doing some of that on my 41 Century along with a .040 head mill to give a higher CR, which is a cheap power adder on these engines over stock. Mine came with the later insert bearing engine with hydraulic lifters. Can't wait to drive it, but still working on rear brakes and shock replacements and dodging MN weather outbreaks! Arrrrgh!

[Ben Bruce aka First Born]

Lawrence, any pics of the OD?

 

  Ben

[neil morse]

Slightly off-topic, but I noticed this NOS Stromberg front carb on Ebay today, so I thought I'd post it here in case anyone is looking for one:

 

https://www.ebay.com/itm/1941-47-BUICK-CARBURETOR/113746451009?hash=item1a7bd11a41:g:2gAAAOSwakpc2A1c

[carbking]

Not a front. Single carb from 1942 40 series.

 

Jon.

[neil morse]

Thanks for the clarification!

[Lawrence Helfand]

On 5/13/2019 at 5:53 AM, Ben Bruce aka First Born said:

Lawrence, any pics of the OD?

 

  Ben

Hi Ben, I will take a couple today! Cheers Lawrence

[Lawrence Helfand]

On 5/13/2019 at 5:53 AM, Ben Bruce aka First Born said:

Lawrence, any pics of the OD?

 

  Ben

Hi Ben, Here's a couple of pics. It clears everything with no problems and emergency brake passes beneath after going through a guide plate. Very smooth in operation and you use the clutch when shifting as you would a fourth gear. I mounted a push pull switch on the steering column within easy reach without looking. I only use it when I'm in third gear like its a 4 speed. What a difference out on the highway and anytime over 50 mph really with all that torque of the 320.  

[Matt Harwood]

2 minutes ago, Lawrence Helfand said:

Hi Ben, Here's a couple of pics. It clears everything with no problems and emergency brake passes beneath after going through a guide plate. Very smooth in operation and you use the clutch when shifting as you would a fourth gear. I mounted a push pull switch on the steering column within easy reach without looking. I only use it when I'm in third gear like its a 4 speed. What a difference out on the highway and anytime over 50 mph really with all that torque of the 320.  

 

 

Dangit, Larry, now you've got me all fired up about putting an overdrive in the Limited again. The install looks very clean. Even better, those guys are two hours south of me so I could just drive the car down there and pick it up later with an overdrive in it...

 

Dangit.

 

Did you buy the overdrive unit direct from Gear Vendors and did you buy their torque tube installation kit with it?

[Lawrence Helfand]

5 minutes ago, Matt Harwood said:

 

Dangit, Larry, now you've got me all fired up about putting an overdrive in the Limited again. The install looks very clean. Even better, those guys are two hours south of me so I could just drive the car down there and pick it up later with an overdrive in it...

 

Dangit.

 

Did you buy the overdrive unit direct from Gear Vendors and did you buy their torque tube installation kit with it?

Hi Matt, I sent you a detailed email a couple of weeks ago with lots of info so maybe you missed it. Let me know and I can resend it. I bought the unit directly and it comes with everything you need for the install. The only thing of issue was the crappy Chinese push pull switch which was super sensitive actuating the solenoid with barely a touch so I replaced it with a good quality unit with a nice vintage looking ivory knob. I wish I was so close as the trailering costs were more then the install labor! Lots more in my email to you regarding costs etc. Yeah you will love it!  Works like butter! 

[Matt Harwood]

I did get your E-mail with all the details, but now that I've seen it in the car and know it's working properly, I'm excited all over again. I have too many irons in the fire at the moment so overdrive for the Limited will probably have to wait until next winter, but now that you've blazed the trail I have no fear about cutting into an unobtainium Limited torque tube. Thanks for that!

[Ben Bruce aka First Born]

WOW.

 

  Ben

 

 

[KongaMan]

On ‎5‎/‎14‎/‎2019 at 1:00 PM, Matt Harwood said:

...now that you've blazed the trail I have no fear about cutting into an unobtainium Limited torque tube. Thanks for that!

How does the Limited torque tube differ from the Roadmaster, etc.?  Are there unique flanges or some other differences beside length?  More to the point, why couldn't you cut up a more common tube and leave the Limited tube alone?

[Jack Worstell]

I recall reading somewhere that  dual carbs were standard in 1941 except that they were optional on series 40

and that in 1942 dual carbs were standard on all series.

 

Is this correct info ?

 

Jack Worstell

[Matt Harwood]

8 hours ago, KongaMan said:

How does the Limited torque tube differ from the Roadmaster, etc.?  Are there unique flanges or some other differences beside length?  More to the point, why couldn't you cut up a more common tube and leave the Limited tube alone?

 

As with many things, it is indeed the length that's important...

 

Roadmaster is on a 126 inch wheelbase. Limited is 139. Both the torque tube and rear end are unique to the Limited; I do not believe a Roadmaster torque tube will bolt to a Limited rear end. However, the engine and transmission are identical. Since Larry has already blazed the trail, I'm not too worried about having them modify it now. I believe they're the same guys who were doing Lloyd Young's machine work and they did a good job putting the overdrive in my '29 Cadillac's torque tube, and I recon that's about as rare as a Limited torque tube.

 

 

Edited May 16, 2019 by Matt Harwood (see edit history)

[1967 - 1997 Riviera]

On ‎5‎/‎14‎/‎2019 at 3:00 PM, Matt Harwood said:

I did get your E-mail with all the details, but now that I've seen it in the car and know it's working properly, I'm excited all over again. I have too many irons in the fire at the moment so overdrive for the Limited will probably have to wait until next winter, but now that you've blazed the trail I have no fear about cutting into an unobtainium Limited torque tube. Thanks for that!

 

Yes, it seems that there has been a continuing discussion of just what owners of these great cars, who want to DRIVE and enjoy them, can do to deal with reducing engine RPMs while attempting to keep up with todays interstate speeds. A recurring idea is to either swap-out the ring and pinion set to alter the axle ratio or swap a rear differential pumpkin entirely. Doing so will reduce the low end grunt needed to pull away from stops or easily climb grades. Not the best way to make use of the straight eight's available torque.

 

Forget all that. Overdrive is the answer, if you can afford it and can get a quality installation done by someone who is knowledgeable and really knows the proper way to do a retrofit. You can have the best of both worlds by maintaining the around town driveability - which is still where you spend most of your driving time anyway - and the desire to keep up with todays vehicles while reducing engine stress on long trips. Plus better fuel mileage, lower oil consumption, less engine noise and longer life between engine rebuilds. A look at new cars being made today and the manufacturers' wide adoption of overdrive should tell you something.

[Ben Bruce aka First Born]

I can attest to what 67-97 said. I changed from a 4.10 to a 3.36 gear. Wonderful road gear.  Terrible 'round town.  Overdrive would be better.

 

  Ben

[Guest]

This was a thread started about 1941 dampers not your rearends. Anybody able to post about induction on 41s?

[Jack Worstell]

I recall reading somewhere that  dual carbs were standard in 1941 except that they were optional on series 40

and that in 1942 dual carbs were standard on all series.

 

Is this info correct  ?

 

Jack Worstell

[neil morse]

Jack, what you say about 1941 is certainly consistent with what I have read about it.  I have also read that dual carbs were continued into 1942, but I don't know whether they were standard on all series in '42.

 

2carb40, thanks for starting this thread.  It's interesting to see the guts of the dampers under the rear carb.  The damper on my car is free and apparently is working correctly, judging by how great my engine runs.  As I have posted before, I hasten to add that this has nothing to do with me.  The car was running like a top when I bought it over two years ago, and has continued to run well.  Also, contrary to some of the experiences that have been reported elsewhere, it idles very smoothly and quietly.

[DonMicheletti]

Having ridden with Neil, I can corroborate what he says. His car runs great at all speeds and has no hesitation or acceleration issues.

 

They did work and can work.

[Matt Harwood]

Here's a look at the flapper. Not a great one, but complete. I sandblasted it and disassembled it since it's going under the rear carb on the Limited which will be synchronous rather than acting as a secondary, so no need for the flapper. It will, however, be a spacer so the carburetor sits at the right height. I'll probably tap the shaft holes and put some small screws in there to prevent a vacuum leak. But this is how it looks.

 

  

 

 

[valk]

That's what my rear damper looks like - valves and counter weight removed. Told the damper was obsolete given today's modern fuel. 

 

Would like to learn more about what Lawrence said about advancing the timing. Is this a common practice to boost power in '41s? 

Peter 

[Matt Harwood]

14 minutes ago, valk said:

That's what my rear damper looks like - valves and counter weight removed. Told the damper was obsolete given today's modern fuel. 

 

I think we've found the source of your excessive fuel flow in the rear cylinders...

[neil morse]

I agree with Matt.  I don't understand what modern fuel has to do with it.  Based on how my car runs, I would advise you to put the damper back in unless you are going to convert to a different system like Lawrence did.

Edited May 19, 2019 by neil morse (see edit history)

[carbking]

20 hours ago, Jack Worstell said:

I recall reading somewhere that  dual carbs were standard in 1941 except that they were optional on series 40

and that in 1942 dual carbs were standard on all series.

 

Is this info correct  ?

 

Jack Worstell

 

I do not have a Buick Master Parts book, however:

 

Carter listed 551s as a single carb for 1942 only for the series 40 and 50

Carter listed 549s as a single carb for 1942 only for the series 60, 70, and 90

Stromberg listed 7-66 as a single carb for 1942 only for the 40 series

Stromberg listed 7-57 as a single carb for 1942 only for the 60, 70, and 90 series

 

Jon.

[carbking]

Quote Valk "That's what my rear damper looks like - valves and counter weight removed. Told the damper was obsolete given today's modern fuel. "

 

Modern fuel should have nothing to do with determining whether or not to use the damper.

 

If an original set-up, with the "dumper" rear carb, and progressive linkage - use the damper.

If the set-up has been converted to two "complete" carbs (the "dumper" carb is not complete), and straight linkage - the damper should not be used.

 

Have NEVER experimented with the original set-up (dumper, progressive) without the damper, so GUESSING!

 

I would expect, ASSUMING THE REAR CARB AND THE PROGRESSIVE LINKAGE ARE CORRECTLY ADJUSTED, that the system would run lean, not rich. Most newer, V-8 engines with multiple carbs had a lockout to prevent the secondary carbs from opening before a certain RPM, thus flooding the engine with air and creating a lean condition.

 

Jon.

Edited May 19, 2019 by carbking (see edit history)

[Guest]

The engine can only use as much fuel/air mixture as developed vacuum will allow. You could stand on the gas pedal of my 58 Pont with stock tri-power at low rpm and it was a pig. At about 35 mph the engine rpms were high enuff to provide enuff vacuum to handle the full throttle position better and acceration was then much more impressive. 

[carbking]

Here is a picture of the bottom of the throttle body of a Compound Carburetion rear carb:

 

 

http://www.thecarburetorshop.com/Buick_rear_TB.JPG

 

Note the presence of idle mixture screws.

 

The rear carb was not a "complete" carburetor. The rear carb has an idle circuit, and a main metering circuit. It does not have a choke circuit, a pump circuit, or a power circuit.

 

The two existing circuits work exactly as they would in a complete carburetor.

 

Stromberg suggests an idle mixture setting of approximately 1 turn on EACH of the two carbs.

 

Note that the throttle plates are designed to completely close. Thus, ASSUMING that the carburetor is correctly adjusted, and the progressive linkage is correctly adjusted, NO FUEL would flow through the main circuit with the damper removed, UNTIL the progressive linkage was opened sufficiently far to allow the throttle blades to open. After the throttle blades started to open, fuel would flow proportionally to the air velocity through the main venturii.

 

The damper assembly is in place, not to prevent overfueling, rather to prevent (or minimze) a significant hesitation because of an instantaneous lean condition if the rear (secondary) carburetor is opened before the engine RPM is sufficient to accept the additional AIR.

 

If the damper is NOT present, fuel flow still would not start from the rear carb until such time as the progressive linkage actually opened the rear carb throttle blades.

 

Jon.

[Guest]

What he said! Vacuum sucks dont it? Some smarties call that negative presure. Litrally, not figuratively speaking!

Edited May 23, 2019 by Guest (see edit history)