1939 Century Starter Switch?

[Ken Wells]

Working on a 1939 series 61 for a friend, at some point the car was converted from original to a toggle ignition switch and a pushbutton momentary starter switch. I would like to return the car to it's original configuration but haven't a clue. I have a schematic that indicates a vacuum switch below the carburetor may have been used in some way. Can someone advise? Thanks!

[Kenneth Carr]

Ken, a link to a photo of what may be your switch is at the end of this message.

I have a different one since my car is a 1941. It is attached to the front carburetor. The unit has a cylinder and piston in it. The rod that the choke valve (butterfly?) is attached to passes through the cylinder and it prevents movement of the piston. The rod has a flat on it. When you press the accelerator half way the rod turns and the flat lines up with the piston which then falls down and hits a pair of contacts that complete a circuit that engages the starter. There is a vacuum line attached to the cylinder. As soon as the engine starts you have sufficient vacuum to suck the piston up and open the starter circuit so the engine stops cranking.

That’s my best understanding of it … may not be perfect but close.

If one were to remove the two wires going to your starter button and attach them to the vacuum switch you would be back in business. I installed a new wiring harness in my car and it came with the correct wires. People put in a dash starter button when this system goes bad. Usually the problem is dirt getting inside the switch and causing the mechanism to clog up.

Here is a link to a photo of the switch:

https://forums.aaca.org/topic/342658-nos-1938-and-1939-buick-vacuum-starter-switch/

Edited December 25, 2021 by Roadmaster71
Problem with link. (see edit history)

[Jolly_John]

Hi, Roadmaster71, and thanks for posting a photo of one of the 1939 BUICK big series vacuum starter switches I still have available. Perhaps Ken can contact me about a purchase.

 

However, Ken, first you should post some photos of the carb that's currently on the '39 BUICK you're working on. Also, it would be good if you could tell us the model number on this carb. It's possible that someone has put a newer carb on this BUICK at some point in time.....a carb without a vac. starting switch provision. That could  be a reason the pushbutton starting system was installed.

 

The correct big series carb for the '39 has a unique base casting that accepts the correct vac. starting switch. So, if this car you're working on doesn't currently have the correct '39 big series carb on it, you're not going to be able to install my (or anyone's) NOS or used vac. starting switch.

 

As an alternative, I have an NOS Stromberg carb for 1941 and 1942 big series BUICK engines available. It is complete with a new vac. starting switch. We'd have to compare the mounting bolt pattern of this carb to that of your current carb to be sure. 

 

I'll send you a PM (the little envelope in the upper right corner of the page) with a few other comments. John

Edited December 25, 2021 by Jolly_John (see edit history)

[buick looks fine for 39]

Roadmaster 71 has it right regarding how the vacuum switch essentially works. Buick used the same vacuum switch in 38-39 320 engines.  40 and later switches were redesigned, but they operated on the same principle. They were essentially a safety device intended to protect the starting circuit. Most switch failures included buildup of gunk over the years, the contact points in the switch could corrode and become pitted, and the diaphragm failed. It's pretty common to see vacuum switches in old Buicks bypassed by some past shade tree mechanic. 

 

The best advise I can give is purchasing a repro shop manual for 1938 plus the supplement manual for 1939 and you'll need both. Also if you have the car for any period of time purchasing a repro 1928-1941 Master Chassis Interchange Manual may be a good idea. They will pay for themselves the first time you use them. .

                                 

                                                                                               Centuries are great cars and they're faaaast

                                                                                                            Thanks

                                                                                                             Leif

[1939_Buick]

More to the good information above. 

 

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

As above 1939 may be a little different to 1942, but still useful

 

A 1939 series 61 will have a 4 bolt carb.  Unsure if JJ's (for a dual carb car?) are 3 or 4 bolt base

As above changing the carb for another is common

 

 

And we like photos!

Edited December 25, 2021 by 1939_Buick (see edit history)

[Jolly_John]

Always lots of good pre-war BUICK help from the guys here on the forum. An update regarding Allan's thought about the bolt pattern on this NOS 1941-42 big series carb I have that I mentioned in my post. It indeed has the 4-bolt pattern, identical to the carb from a '39 big series engine. John

[neil morse]

Here's a alternate opinion that may or may not be welcomed: you might want to consider just leaving things as they are.  It was not just "shade tree mechanics" who bypassed this system.  It had many problems, and could result in significant damage to the ring gear on the flywheel when things went bad.  Many cars were converted to a push button in order to have a more reliable, less damage-prone, system.  My '41 had been converted by a former owner when I got it, and I've just left it the way it was with a push button under the dash instead of the accelerator-activated switch on the carb.  There is no down side, as far as I can tell, to having the alternative set up.

[Rock10]

27 minutes ago, neil morse said:

Here's a alternate opinion that may or may not be welcomed: you might want to consider just leaving things as they are.  It was not just "shade tree mechanics" who bypassed this system.  It had many problems, and could result in significant damage to the ring gear on the flywheel when things went bad.  Many cars were converted to a push button in order to have a more reliable, less damage-prone, system.  My '41 had been converted by a former owner when I got it, and I've just left it the way it was with a push button under the dash instead of the accelerator-activated switch on the carb.  There is no down side, as far as I can tell, to having the alternative set up.

Just not original. And to some people that is everything, the reason they love these cars.

[neil morse]

2 hours ago, Rock10 said:

Just not original. And to some people that is everything, the reason they love these cars.

 

I get that.  I just meant that there's no practical downside to leaving it with the push button alternative.

[Ken Wells]

8 hours ago, Jolly_John said:

Hi, Roadmaster71, and thanks for posting a photo of one of the 1939 BUICK big series vacuum starter switches I still have available. Perhaps Ken can contact me about a purchase.

 

However, Ken, first you should post some photos of the carb that's currently on the '39 BUICK you're working on. Also, it would be good if you could tell us the model number on this carb. It's possible that someone has put a newer carb on this BUICK at some point in time.....a carb without a vac. starting switch provision. That could  be a reason the pushbutton starting system was installed.

 

The correct big series carb for the '39 has a unique base casting that accepts the correct vac. starting switch. So, if this car you're working on doesn't currently have the correct '39 big series carb on it, you're not going to be able to install my (or anyone's) NOS or used vac. starting switch.

 

As an alternative, I have an NOS Stromberg carb for 1941 and 1942 big series BUICK engines available. It is complete with a new vac. starting switch. We'd have to compare the mounting bolt pattern of this carb to that of your current carb to be sure. 

 

I'll send you a PM (the little envelope in the upper right corner of the page) with a few other comments. John

 

 

Thanks guys for the excellent and helpful responses, hopefully next week when Christmas winds up and I can get some garage time I'll test the switch, drop the steering column and test the key operated switch. 

Edited December 26, 2021 by Ken Wells (see edit history)

[Brooklyn Beer]

Isn't there a safety as well between the generator circuit built into this?  My 49 had been converted to 12 volt for AC and this was removed. After 3 times doing a mad dash around the car to pull the cable off the battery terminal because the switch stuck and kept cranking over I added the bump switch. The manual goes over for that year car. I have a brand new NOS vac switch I never installed sitting here.

[2carb40]

16 hours ago, Jolly_John said:

Always lots of good pre-war BUICK help from the guys here on the forum. An update regarding Allan's thought about the bolt pattern on this NOS 1941-42 big series carb I have that I mentioned in my post. It indeed has the 4-bolt pattern, identical to the carb from a '39 big series engine. John

Just a quickee, all 320" two barrel SINGLE carb Buick engines had a four bolt carb base. On my '41 Century, I used adapters to bolt later four bolt base carbs to my three bolt 320" dual carb manifold, (shade tree) experiment. Oops, lightning-proof trousers needed! Sorry, remove if needed.

Edited December 26, 2021 by 2carb40 (see edit history)

[Jolly_John]

Ken, you have what appears to be the right carb and vacuum starter switch on this '39. I don't know if the vac. starting switch on this carb is bad. However, if you determine it is, I have an NOS one available for $60, plus shipping.

 

Also, you shouldn't have to mess with the steering column to electrically test the ignition on/off switch. The wiring connections (two) are exposed on the back of the switch. I'd check these first before worrying about the sliding steering column lock that's related to the switch. If you don't have the manuals, you really could make use of the original 1939 shop manual supplement I have for sale, plus the '38 shop manual, as was mentioned in one of the above postings.

 

You should have received a PM (little envelope at top right of page) with more info. John

Edited December 26, 2021 by Jolly_John (see edit history)

[Ken Wells]

15 hours ago, Rock10 said:

Just not original. And to some people that is everything, the reason they love these cars.

Yes, I had the dust cover off the clutch housing to highlight the timing marks and could see the starter gear on the flywheel was in really bad shape and had already been flipped.

[Kenneth Carr]

On 12/26/2021 at 1:37 PM, Ken Wells said:

Yes, I had the dust cover off the clutch housing to highlight the timing marks and could see the starter gear on the flywheel was in really bad shape and had already been flipped.

Ken, in light of your discovery it might be wise to take Neil’s advice and stick with the button until you invest in a new starter gear.

[Ben Bruce aka First Born]

On 12/26/2021 at 12:37 PM, Ken Wells said:

Yes, I had the dust cover off the clutch housing to highlight the timing marks and could see the starter gear on the flywheel was in really bad shape and had already been flipped.

Ken, you might be surprised what can be done with a small grinder, or file.  Mine was pretty bad . I cleaned it up, one spline at a time, several years ago.  Still ok.

 

  Ben

[2carb40]

On 12/26/2021 at 12:37 PM, Ken Wells said:

Yes, I had the dust cover off the clutch housing to highlight the timing marks and could see the starter gear on the flywheel was in really bad shape and had already been flipped.

Send me a private message if you decide you want to replace damaged ring gear and/or flywheel and would like a photo. GregJ