1938 Buick Spl 2dr Sdn

[neil morse]

3 hours ago, Wm Steed said:

From past experience I knew that the rear carb did not have a choke, did not know about the other anomalies. I have no idea why Buick eliminated the accelerator pump from the rear carb.

The answer is actually pretty simple.  The carbs on the Buick system are sequential.  Here's how it's described by the Buick Heritage Alliance:

 

"The compound carburetion used in 1941 and 1942 was the forerunner of the 4-barrel carburetor.  Normal operation up to about 50 mph, including starting, used the front carburetor, although both carburetors functioned at idle.  When greater speed and/ or acceleration was desired, linkage activated the rear carburetor which had no choke."

 

So most of the time, the engine is using only the front carb.  The system was only used for '41 and the low-production '42 year.  It apparently got a reputation for being difficult to properly adjust, but I haven't had any problems with mine (and I don't read many complaints from '41 and '42 owners on the forum).  Some people have converted the system to run two "front" carbs in parallel, as Ben mentions, so I'm sure you can make your set-up work with the carbs you have.  If you do some searching on the forum, you will find some discussions of how to do the conversion.

[carbking]

Wiith the progressive linkage, the engine got a reputation for horrible fuel economy; and then fuel rationing entered the picture. The fuel distribution in the various cylinders is not ideal. This is the idea behind using straight linkage.

 

On a similar note, I used to regularly rebuild Chevy 6 cylinder carbs that came in with the accelerator pump disconnected. If you only can acquire so much fuel per month (and not very much), you tend to try to save what fuel you can.

 

Jon

[carbking]

On 3/6/2024 at 12:10 PM, neil morse said:

From the manual:

 

The chart is incomplete, as is much data in repair manuals, as they are generally printed prior to the product of the vehicles.

 

Both engines had these carburetors discontinued, and different carbs  replaced them mid-production year.

 

The 40/50 7-42 was replaced by 7-46, and the 7-43 was replaced with 7-47. This took place 25 March 1941.

 

The large engine 7-39 was replaced by 7-44 an the 7-41 was replaced with 7-45. The large engine replacement was 24 March 1941.

 

7-46 was held over for a part of 1942, but then replaced.

 

The Carters also had early and late production.

 

Jon

[Wm Steed]

A big thank you to everyone that has chimed in with info, etc., about my project, it looks like the repairs/modifications will be done by the end of the month, then we'll find out the good, the bad and the ugly,

Since fuel economy is not a big issue with the car, it will never be a daily driver, nor will it be a trailer queen, actually it's more of a King because it's a Buick.

About twenty years ago I stumbled upon a '38 Buick Spl coupe in Eastern Idaho, it was a very nice original car that had been out off service for many years, The owner was reluctant to sell the car, I was very interested, mainly because of the overall condition of the car and the fact that the engine had Buick Compound carbs, quite a shock when I first opened the hood. At the time I could not make a deal on the car, when I went back a couple months later the car was gone. I saw the car at a car show about five years later.

I picked up an original '41 Buick shop manual yesterday, $12.00 on eBay... I prefer original manuals in lieu of reprints. The reprints I have seen seem to be missing a lot of info. Wm.

[Wm Steed]

We are making progress with the carbs, fuel lines are all hooked up. The mechanic (Chris) working on the carbs has done a lot of research on the '41-42 system that Buick used, in his opinion eliminating the accelerator pump would cause the rear cylinders to run lean, Chris also did not like the progressive linkage. The carbs are now connected directly together using hiem joint linkage just like the Stombergs on my 36 Ford flat-head.  Wm.

[Wm Steed]

If things go well the 38 Buick will be running by the end of the week.

The exhaust system is just about done, we did not use the same system as original to the '41-42 two head pipes going into one head pipe then exiting the engine compartment into one muffler and one pipe to the rear of the vehicle.

We ran two pipes from the manifold extending from the side of the trans into a double chamber that are connected together within the muffler to equalize the two pipes exiting the muffler to the rear of the vehicle.

The carbs are all hooked up, fuel lines ran and the linkage is in place controlled by a cable hooked to the throttle peddle. We hooked up one automatic choke hooked to the front carb and the original choke chimney.

When the car is running it will be taken to the alignment shop to have a four wheel alignment done.

After-market turn signals and A Guide B31 '39-'47 back up light is being installed. We modified the 38 park lights, converting them to double filament for park and turn.

[EmTee]

Looks good.  So, please refresh my memory; are the two carbs slaved together (i.e., working in tandem) or is it a progressive linkage (one opens ahead of the other).  I thought you said that you were using the former configuration.

 

Edited April 11 by EmTee (see edit history)

[Wm Steed]

In my earlier contributions to the story about the modifications to my 38, I mentioned that we had done a lot of research on Buicks compound carb setup, therefore we used two front carbs in lieu of the special carb w/out a choke and accelerator pump. We used a custom made slave linkage system with the carbs synchronized together.

Buicks system caused the rear cylinders to run lien resulting in poor performance and bad fuel economy.

Looking at the pix of the carb linkage tends to make the system rather cluttered up do to all of the various stock linkage that the Stromberg carbs have.

We also added a PCV system to the engine which added to the clutter, We are going to add a fresh air intake duct to the side of the engine compartment under the left head light pod which should clean things up.

The use of a small cable to the throttle in lieu of a bell crank and rods also cleaned thins up.  Wm

Edited April 11 by Wm Steed (see edit history)

[drhach]

4 hours ago, Wm Steed said:

..

Buicks system caused the rear cylinders to run lien resulting in poor performance and bad fuel economy.

.

I get the sentiment behind this belief, but the more I think about it the more I wonder if it is really true. I have a factory dual carb setup and all of my plugs look pretty much the same. Also, the consensus is that Buicks are well engineered. They must have considered this setup. Would they have skimped in the intake department; especially to such an extreme? Even a single carb system has the outside cylinders placed pretty far away.

 

It's a closed system. Anywhere air gets drawn in, there's something there to mix it with gas. That mixture then travels where it's needed. If anything, that long run may cause throttle response issues, but it seems like if the system is set up as the factory intended it, there should be no significant issue with mixture for any cylinder. The carb experiences demand and mixes accordingly, it doesn't care where it goes after that.

 

Just food for thought, my nailhead has basically the same setup. It's a progressive linkage with one carb having only high-speed jets and an idle circuit. So, if it was wrong, Buick did it wrong twice. And they sold thousands of them. 

[carbking]

4 hours ago, drhach said:

......Just food for thought, my nailhead has basically the same setup. It's a progressive linkage with one carb having only high-speed jets and an idle circuit. So, if it was wrong, Buick did it wrong twice. And they sold thousands of them. 

Buick had factory multiple carbs on the straight 8 in 1941 and 1942 (the "compound carburetion" set-up) with a primary carb and a secondary carb with limited calibration (a so-called "dumper" carb). A compound single-barrel set-up was tested circa 1935, but did not make production.

 

Buick had factory dual quads in the early to mid-1960's. Again with a primary carb, and a secondary carb. However, Buick had learned their lesson from the compound carburetion, and the "secondary" (front) carb used in the dual quads was missing ONLY the choke circuit. Idle circuit, pump circuit, main metering circuit, stepped metering rods, auxiliary secondary, high speed circuit; just like the primary (less the choke), but with slightly different calibrations. The primary side of the secondary carb came in before WOT unlike the compound carburetion "dumper" carb.

 

The secondary AFB would run as a single four if one did not need a choke.

 

Progressive linkage was used (the carbs were too large), and for the street cruiser we have proved more than once that a pair of smaller carbs and solid linkage has much superior driveability to the progressive linkage.

 

Jon

Edited April 12 by carbking (see edit history)

[1939_Buick]

Manuals - parts books a few year after your car (~engine) tend to have running changes incorporated.  As above the first edition (1941) is written ~printed before production

 

Download the 1942 Buick shop manual for free. All of it section by section.

Or click the pdf link to pay.

http://www.oldcarmanualproject.com/manuals/Buick/1942/Shop Manual/

It is very comprehensive and has information that can be used with all straight 8’s.

It has more information than was included in older “Shop Manuals” before 1942

 

From 1939 Buick sloped the engine. so the intake manifold has a step.  What most people do when putting dual carb on 1938 and before, is machine a small wedge (fitted under carbs) to take into account of the 1939 & latter slope.  Carb's then sit *horizontal* .

Image is a 1938 and a 1939

 

Edited April 13 by 1939_Buick (see edit history)

[Wm Steed]

Today is the big day to take the 38 for a road test, Have to do some last minute adjustments to the timing (Pertronix ignition ) and some fine tuning /adjustments to the carbs.  Wm.

[Omarine]

20 minutes ago, Wm Steed said:

Today is the big day to take the 38 for a road test, Have to do some last minute adjustments to the timing (Pertronix ignition ) and some fine tuning /adjustments to the carbs.  Wm.

Very interested in that T5 set up… im sure the testing will go well. Please keep the updates coming. Cheers

[EmTee]

Don't forget your cell phone! 

[Wm Steed]

Yesterday was a big day for my 38 Buick, the owner of the shop, Troy, that has been working on the car and the  mechanic that has done most of the work took the car for a shake down cruise around town.

Troy and Chris were very impressed with how the car handled, the engine was very responsive, a slight amount of lag under full throttle which they were able to quickly adjusted away. Chris really liked the T-5 trans, said it was very smooth and quiet. The brake booster we added worked very well, light to the touch with good response.

The car is back in the shop for a complete check over on all of the fasteners, etc.

I really like the original 41-42 Buick air cleaner, looks great sitting on top of the Stormbergs, however, I don't like the oil bath feature. Following my suggestion the, air cleaner was modified to eliminate the oil bath and retro fit the unit to accommodate a modern disposable paper filter unit, a 6.5 x 3.5" WIX filter, 

One of the features of the T-5 trans is that since it is a modern trans it has provisions for a back up light. I really like modern touches to vintage cars, with that thought in mind I searched the internet for a. back up light. low and behold I came upon a NOS Guide B31, 1939-47... A stand alone light that would bolt to the bumper bar, and could be considered to be original equipment. A simple solution to a potential problem. Wm

[Omarine]

William, nice work- how did your guys handle the T5 cross member? I will scroll through again to study your axle setup. Thanks 

[DonMicheletti]

What is the tube running along the spark plug cover used for?

[Wm Steed]

In response to Don's question... The tube running down the right side of the engine on the cover plate is a vacuum line, 5/16" steel with a special non corrosive coating that originates in the intake manifold, around the front of the engine, to the original Buick road draft tube, crank case ventilator, which we blocked off for access for a PCV from a GM 250 CID inline engine.

The vacuum line then continues down to a point adjacent to the trans where it connects to the HYDRAVAC brake booster.

Installing a PCV system on vintage cars is a little trick I learned in the late 1960's When California passed a law  "called NOX" which required that ALL Vehicles had to have a closed crankcase, PCV. The PCV system became mandatory in 1963 for all vehicles under 9,500 lbs sold in California.

The NOX program was a nightmare.

I got around it by installing a PCV system from a '64 Ford 292 CID V8 on my '56-57 T-birds and my '59 Ford F100 V8 292.

 

[Wm Steed]

Attached are some pix, the second one shows the stock exhaust head pipes on a '41 Buick with compound carbs. The first pix shows the head pipes as we built them, with the third showing the dual chambered muffler and twin head pipes

We felt running both head pipes into one 2" pipe would tend to be restrictive, therefore, we ran two pipes down and under the car,into a special dual chamber/pipe muffler that cross's within the muffler, exiting into two head/tail pipes. wm.

[Wm Steed]

In addition to the mechanical improvements we have done to the 38, we added a turn light system.

The turn light switch was an over the counter 6v switch with hazard lights built into the switch.

The only problem we had was turn signal lights for the front end. We were able to find conversion staggered pin receptacles for 1157 6v bulbs that would fit within the original parking light housings.

Interestingly, when the right parking light was taken apart we found that the inside of the assembly was almost as clean as the day the car was made, with one exception, at some point in time the lens had been broken. The lens had been glued back together. The glue was of an inferior quality so the lens fell apart.

A pair of new lens were purchased from Bob's Automobilia in Templeton CA.  Wm.

[Wm Steed]

Yesterday was a big day for me and my 38 Buick. The Buick is running, and quite well to say the least. Pressing the gas peddle to the floor three times set the choke on the front carb and the engine starts right up, staying on a fast idle until the throttle is depressed.

The exhaust with the dual chambered muffler is very quite, sounds like a V8 🤤..

I should add that the car had a large glass pack muffler with a small 1.5 inch tail pipe, The exhaust was quite laud, like a truck.

It will a few more days before the 38 is road ready, few little adjustments have to be made. I like the black wall tires in lieu of the wide whites the car had when I bought it. The original spare tie was still the trunk when I bought the car, it was gray with pin strips. i decided to paint whe wheels gray. I thought about red, then said no, lets keep things as close to factory original as possible.

Looking at the rear of the car you can just barely note the dual exhaust tips. I used tips that slightly turn down, to down play the dual exhausts, which would lead the average person to think the car has a V8 in lieu of a straight eight. Wm.

Edited April 26 by Wm Steed
spelling (see edit history)

[EmTee]

20 hours ago, Wm Steed said:

The exhaust with the dual chambered muffler is very quite, sounds like a V8 🤤..

The car look good; I like the chrome turn-downs, but I might 'distress' the finish a little to better match the rest of the car.  Someone who doesn't know will assume that it's powered by a SBC.   Is the muffler internally configured to keep the two sides separate, or is it open; functioning like a crossover pipe?

[Wm Steed]

I have to agree with EmTee' comment about the new chrome exhaust tips, I think I will figure out a way to dull them down to match the bumper. The rear bumper has excellent original chrome, a little road rash from 86 years of public parking, I might try to buff the bumper up a bit.

I tend to listen to a different tune, if I wanted a V8 in my Buick I would use a Buick V8, and not just a recent 350, etc.

I have a completely rebuilt Buick 401, bored out to about 413, that is highly modified, I also have a ST400 switch pitch transmission that was built for my '40 Buick Super 4dr. I wanted a 425 nail-head, but could not find one that was re-build-able.

I am not sure just how the pipes inside of the muffler are configured, I was told they form a tight H within the muffler to balance the pipes.

A question was asked several comments ago about what we did with the transmission rear mount.

We removed the stock cross mount which was bolted to the frame, no alteration to the X member was required. A new cross member was fabricated and bolted to the frame to support the T-5 trans.

The T-5 trans w-S10 tail housing is four inches longer than the original three speed trans, which did not present a problem.

In the early part of this forum I made a comment about the size of the X member opening where the original trans was located. I made the assumption that the Special chassis was originally made to accommodate the Hydramatic (shiftless trans), an option that was only available in the Specials.

As it turned out, the 440 rear axle ratio would have worked with the T-5 OD ratio. the problem was the torque tube drive line, rear suspension, and closed universal housing that would not adapt to the T-5 S10 tail housing.

I think that the use of C10 Chevy trailing arms in lieu of the original Buick radius rods made a much better, more stable rear suspension. Wm

[Wm Steed]

Progress is being made with the completion of the work on my 38 Buick. Mostly just little odds and ends..

In an earlier contribution to this forum I mentioned that we had modified the crankcase breather on the push rod cover for a PCV system, routing a vacuum source around the engine to service the PCV

and power brake booster.during course of the alteration of the dual carb air cleaner from an oil bath system to a modern air filter unit. During the course of the modification we noted that the upper portion of the filter assembly there was a port in the unit that appeared to be a port to a breather hose from the valve cover to the air cleaner, thereby making a complete loop to close the crankcase venting system, It did not take much looking around to fins a valve cover cap, hose and fitting for a Ford FE, 1968 to 79 engine. New technology meets and improves the good ole days. Wm.

 

Edited May 1 by Wm Steed
spelling (see edit history)

[DonMicheletti]

How does the car perform at highway speeds with the differential and engine modifications

[Wm Steed]

At this point in time I can not respond to Don's question as to how the car performs at highway speeds. We are in the process of tying up some loose ends to make the car road ready, once it is road ready it will go to the alignment shop to have a four wheel alignment done, once this is done we will do some speed, road, reliability testing. 

Edited May 4 by Wm Steed
splelling (see edit history)

[Wm Steed]

Getting closer to road test time,keep finding loose ends to tidy up. We did not like how the air intake for the carbs, in its original configuration relied on air that would be super heated by the exhaust head pipes. I realize that the compound cabs in a '41-42 would have been in a larger engine compartment than my 38. The only pix I have of a '41-42 with the compound carbs shows the throat of the air cleaner sitting open with no protection from road debris, etc.

I thought the situation over and came up with a plan to bring clean cooler air from the outside of the engine compartment to improve engine performance.

we used a PERKO marine air scoop that we located under the left headlight pod. Utilizing some ABS 3" ducting material we route the incoming air to the throat of the air cleaner.. Wm.

 

 

 

 

 

 

 

 

 

[Wm Steed]

Attached pix show the connection of the carb air duck to the exterior air scoop and the air cleaner, and the exhaust head pipes without the splash pan, and a second pix showing the left splash pan installed.

The forth pix shows the right side of the engine with the splash pan installed. Wn.

[neil morse]

On 5/12/2024 at 8:56 AM, Wm Steed said:

The only pix I have of a '41-42 with the compound carbs shows the throat of the air cleaner sitting open with no protection from road debris, etc.

Just for clarification, the stock set up in '41-'42 was similar to what you came up with.  There was a hose/duct from the air cleaner down to an opening behind the radiator grill.  Your scoop set up looks very sharp

 

 

 

 

Edited May 13 by neil morse (see edit history)

[Wm Steed]

Thank you for the nice comment Neil... I try to do things right the first, in lieu of having to redo them. Wm.

[Wm Steed]

We thought we were close to finishing up my 38 project, the only major item left to do was a four wheel chassis alignment.. The shop that is doing the work on the car could not find the real stabilizer bar.

The 38 Buick was the first Buick to have a rear stabilizer bar, this is probably due to the fact that the 38's were the first car in the Buick line to have coil springs on the rear, therefor a stabilizer bar was required to control body roll, a problem that is minimal on vehicles equipped with parallel springs.

The 38 Buick series 90 does not have a rear stabilizer bar, possibly because the vehicle has parallel rear springs due to it's size and weight.

I did some networking around the country, found a complete stabilizer bar in Minnesota.

We are taking advantage of the parts delay to tidy up some other issues we encountered with the car. Wm  

[DonMicheletti]

I have a '38 Special 46s and a '38 Roadmaster 81. Neither have stabilizer bars nor ever did.

 

Your photo is of a later car based on the flange at the differential housing.

 

However, I do think a stabilizer bar would be a good idea.

Edited May 24 by DonMicheletti (see edit history)

[Wm Steed]

I am very much aware of the fact that the pix I added to my earlier contribution is of a later vehicle,it is from the '41 shop manual. When i looked through my '38 Shop manual, I found no reference to a rear stabilizer bar in my Buick 1938 Shop Manual, dated September 1937l.

My '38 Special is reputedly a one owner car that for all practical purposes is at least 98% original with 37K mils showing on the odometer.

When I was doing a survey of my car to make a list of the parts I needed, prior to disassembly, I noted the rear stabilizer bar and the rubber bushings at the frame mount and link to the rear axle housing. I noted that the  rubber bushings were in good shape. In light of their age I thought I should order new bushings. When I ordered the bushings I was told that they were an out of stock item.

I called David Tacheny in Champlin Minn to see if he might have a rear stabilizer bar for a  '38 series 40, Davids response was that he had several, the series 40/50 both had the same bar. David is sending me a complete assembly for my car.

It might be interesting to make note that the Buick Shop Manual states that the stabilizer bushings will last the life of the vehicle.

Hmm? My car is 86 years old so I guess I don,t need a rear stabilizer bar any more. Many people are of the mistaken believe that the Stabilizer bar, front and rear, are "sway" bars" Wrong, they are meant to control body roll, the '38 and later Buicks have Panhard/ Chassis tracking bars on the rear. Wm

Edited May 24 by Wm Steed (see edit history)

[DonMicheletti]

Not to, necessarily argue, but I bought my Special 51 years ago and it was was an original, unmolested original car. Not reputedly.
I bought the Roadmaster 40 years ago in its original condition. It has no trace of ever having had a stabilizer bar either.

There is no mention in the shop manual of a rear stabilizer bar. Was that a documented, late in year, addition? I'm curious.

 

[EmTee]

6 hours ago, Wm Steed said:

...the '38 and later Buicks have Panhard/ Chassis tracking bars on the rear.

Just to be clear, the '38 Buick did require a Panhard or "track bar" to maintain the side-to-side location of the rear axle with respect to the chassis since unlike the leaf springs used previously, the coil springs do not provide the necessary lateral constraint by themselves.  The stabilizer or 'sway' bar that came along later applies torque to counter body roll through turns.

 

 

[Wm Steed]

Many years ago I came to the conclusion that "roll stabilizers and Panhard/track bars" are probably one of the most misunderstood  items every put on an automobile. My first five cars were GM built, '38 and later. then I bought a '36 Ford that did not have a very stable platform, it was not until 1940 and 1946 that Ford put stabilizer/tracking bars on their cars.

Within a year of buying my 36 Ford, 1952, I put a rear tracking bar, (sway bar) and a front stabilizer bar on the 36 Ford. Wm.

 

[DonMicheletti]

I know the difference between the two "bars".

I wish my '38's had rear stabilizers.

 

I'm tired of having the chrome rubbed off the door handles in a turn.

[Wm Steed]

Don, I purchased a complete rear stabilizer bar assembly for my '38 Spl from   David Tacheny in Champlin Minnesota on May 21, 2024. David is one of the go to guys for '38 Buick parts, I got his name from the 36-38 Buick Club..

For what it is worth, as to how original a vehicle is, could be an oxymoron subject. If the vehicle was purchased from a first person original owner and that person had handled any repairs, etc., to the vehicle, then and only then, can it be assumed that the car is original, they are only original once, that being at the time of manufacture.

I purchased my '38 Spl from a man in Denver who had purchased it from a broker that had obtained the car from the 'reputed' original owner. There were no sworn statements supplied with the car, just a few old work invoices, old service stickers on the door jamb, an original 1938 Buick Shop Manual, owners manual, with a few hand written notes, and a set of non-original, 39 and later Buick hub caps.

When I received the car via a commercial carrier I noted that the tires were 700x15, not correct for a '38 Spl, later on it was noted that the brown rubber front floor mat was in like new condition, after 80 plus years,this was suspect.

Upon close inspection we found that the mat was embossed with 39 Ford All..

Throughout the seventy plus years that I have been dealing with old cars, I have encountered many that had doubtful parentage. Wm.

[DonMicheletti]

I'd love to see a photo of that stabilizer to see if mine can be retrofitted.

If you still have the original rear axle, I'd like to see how the stabilizer was attached to that.

[MCHinson]

26 minutes ago, DonMicheletti said:

I'd love to see a photo of that stabilizer to see if mine can be retrofitted.

If you still have the original rear axle, I'd like to see how the stabilizer was attached to that.

Don, this photo shows a partial view of one from above with the body removed during restoration of a 1938 Model 61.