1925 Buick std 6 distributor shaft

[KEK]

Hi everyone -

 

I just got my starter generator back from the rebuilder and I found out it was a real process including new brushes and wiring. The SG needed more work than I thought and expensive but hopefully this will solve the sliding gears from being damaged when the starter pedal is engaged.

 

I thought I would take this opportunity to swap the pot metal distributor with a metal housing I got from Hugh. So first I set the point gap with a dial indicator on the bench and found a lot of variation on the 6 lobes on the cam. When setting the gap to obtain an average of 0.020 the individual gaps ranged from the smallest at 0.0175 to the largest at 0.0235. Even though the engine seems to run okay I thought I would try and correct the worn cam before I replaced the distributor.

 

I have another distributor shaft that doesn’t have worn lobes that I want to replace the other shaft with. However when I examined the good shaft I saw spiral groves cut in the shaft just below the counter weight plate - see photo. Does anyone know if these grooves are supposed to be there?

 

My other option would be to just swap out the cam itself but I don’t know if the cam can be removed from the shaft. On my Model A distributors the cam simply unscrews from the top of the shaft but I don’t know if this is true for the Buick. Does anyone know I the cam can be removed from the shaft?

 

Thanks and hope everyone is in good health - Ken

[Old26Buick]

I replace the dist on both my 27 and 27 Buicks. Used a 28 or latter dist and can get point cap, rotor and cond.  from any parts place for around$45.

[Hubert_25-25]

Ken, 

   The cam block is a separate part of the shaft.  If you remove the 3 springs from the underside, the cam section comes off the top.  Be careful not to damage the springs.  

The shaft merely needs to be smooth in the bearing area.  I am not sure about the value of the dial indicator.  The timing of the points opening is what establishes when the points fire.  That probably has not changed as it occurs at the base of the cam lobe.  The fact that there is a little variation in the amount of gap as the points ride over the cam is not as critical.   If it were mine I would just clean it up and see how it does in service.  It is easy to change out later if necessary.   Someone may have a replacement shaft.  I may even have one.  Hugh

Edited February 28, 2021 by Hubert_25-25 (see edit history)

[KEK]

Hi Hugh -

Interesting difference between my two shafts. The shaft that I am currently using, with the worn cam lobes, is 5.300” in length. The other shaft shown in the photo above with the spiral groves and decent cam lobes, is 5.136” in length. Not sure if the shorter shaft would matter but it seems to validate your assumption that it might be a replacement shaft. Unfortunately, this shaft is badly worn in the bearing area and can’t be used so I am interested if you have a good shaft. My gear, weights, springs and plate seem good so just need a good shaft. Please let me know If you have one. Thanks!

[Brian_Heil]

The distributor cam lobes are well worn on my 1923 6 cylinder but uniformly so.  I can still get the correct degrees of dwell with a dwell meter and pay no attention to the point gap that results in the correct dwell.  If you can get the correct dwell, you will be fine.  Dwell angle, is dwell angle.

Edited March 1, 2021 by Brian_Heil (see edit history)

[Mark Shaw]

Ken,

     Perhaps you should just dress the high lobes to match and have a uniformly worn cam like Brian's.

[KEK]

I’ll try to carefully dress up the lobes so they are uniformly worn. I have a difference of 0.006” between the closest point setting of 0.0175” and the largest 0.0235”. That’s when the median gap is 0.02“.

 

But from what you guys are telling me it sounds like the variance between the lobes doesn't matter, just the dwell. But since the amount of dwell is determined by the point gap seems like to me the dwell would also vary proportionally with the point gap? 

 

Your correct that even though my point gap varies a lot the engine does seems to run okay. I was thinking if I could reduce the point gap variance then the engine might run smoother. However, it sounds like reducing the point gap variance really wont change anything.

 

So what point gap should I shoot for if its not that critical. Just use a feeler gage and get in the ballpark of a median gap of 0.020” or do you recommend something closer like 0.18”?

 

Thanks for all of your input. Ha after all of these years I have been so careful to adjust my point gap as close to factory recommendations as possible. There are so many experts on this forum that I learn something new on this board every time I ask a question! 

[Grimy]

The dwell angle is what makes the car run properly.  The point gap is an easily measured mechanical expression of the dwell (the setting necessary to produce the desired dwell) when the distributor is new and the lobes not worn.

 

I leaned this lesson almost 60 years ago as a teenager when my newly-acquired 1950 Pontiac 6 ran like cr*p with new points set at the specified (approx) 0.020.  The dwell was all wrong.  A mentor told me the cause and to narrow the point gap to compensate for the worn dist cam lobes until I achieved the proper dwell.  That point gap to achieve the proper dwell was about 0.014 as I recall.

 

In my experience dwell specs don't seem to show up in repair manuals until about the late 1930s.  I suggest asking other owners for their recommended dwell settings, and adjust point gap as necessary to achieve that dwell.  Then make a note of it and keep it with the car.

[KEK]

Thanks for the explanation. I will need to purchase a dwell meter. So does anyone know what the proper dwell should be for a 1925 standard 6?

[Grimy]

@KEKwhat others tell you will be based on how much their own lobes are worn.  If someone replies, try their settings first, but you'll probably have to do it by trial-and-error--reducing gap from the manual's specification gradually until you find what works best for your car.

 

Re dwell meters:  If they are externally-powered, all those on the market today will be for 12V systems.  In that case, set any decently-charged 12V battery (a small alarm backup/gate opener sealed battery is my go-to) on your running board to power the meter.

[KEK]

Harbor freight has a Cen-Tech multimeter with a dwell function that I am going to go down and get.  I have had good luck with The Cen-tech brand. Last day of their sale =-). Can I just power the meter with the 12v battery And turn the rotor by hand or do I also have to start the car to check the dwell.

[Brian_Heil]

[Brian_Heil]

Adjusting the points on an early Buick is a bear.  That tiny locking nut is hard to get to.  With your meter telling you where you are, tweak the points arm (as in slightly bend) with a pair of needle nose players and you can dial it right it.  I won’t tell if you don’t tell. 

[KEK]

Ha I won’t have to bend my points arm since I have modern points. They still are a little hard to tweak but not bad.

 

So I should reduce the point gap until I get close to the 30 - 35 degrees. 

[Hubert_25-25]

Ken, 

Please post a photo of your modern points installation as I am considering this upgrade.

    

My 1925 Buick Standard purrs.  These are my tune up notes.

Plug gap is (I think .030) but I would need to double check this.

Points spec is .018 or .020.  I have old points and they take a 5.5 and a 6 mm wrench

Dwell is 26 degrees with my Sears dwell meter @.018 gap

Dwell is 28 degrees with my Sears dwell meter @ .020 gap

I was expecting 35 degrees was what I would use, but I set the point gap with the feeler gauge, then I recorded the dwell.  The dwell number was much lower than expected.  Maybe that is the worn cam, but it does not look that worn.  A dwell meter makes it easy to check what the factory spec is, and then you can modify and see which dwell gives the best performance.  I also got a slightly different dwell with another brand dwell meter.   (I have dwell meters from the 70's that likely lived a life of abuse.)

I eventually set the dwell at 26.

Timing is on the 1-6 line on full retard (not the 7 degree after TDC) which is spec.  Modern fuels and you can run a little more advanced for better performance.

At idle, RPM is 380 on full advance, 300 RPM on full retard.

 

vacuum gauge (with the vacuum tank line disconnected) is 16mm Hg on full retard.  18-19 mm HG on full advance.

Leaning out(turning the fuel screw in on the bottom) will raise the vacuum some - as high as 20 mm Hg.  But that is too lean, and the engine will backfire in the intake, so it needs a richer mixture.  Fuel mixture screw is set at 3/4 turns open.  Remember to loosen the packing nut before turning the adjustment or you could break off the adjusting wheel.

 

Air valve screw is set flush with the end of the tab that lays against the side of the big screw.  

 

Look at your plug wires at night to ensure no cross sparking.  I have seen that with new plug wires.   The wires also reside in a cover on the side of the engine.  I built a plastic shield to keep any engine oil off them.  

 

Hugh   

 

[Brian_Heil]

Most modern spark plugs are taller than originals.  Watch for grounding to the spark plug cover.  Add boots.  

[KEK]

Hi Hugh -

 

Here are a few photos of the modern points mounted in the distributor. Let me know if you want other measurements or photos. I’ll have the distributor out until I get my rebuilt SG installed in a couple weeks so no problem if you need more information.

 

My dad installed the modern points so I can’t give you a part number. The length of the base is about 2.1” long. The distance from the stud that mounts the points on the breaker plate to the screw that holds the points to the base is about 1.5”.  I can’t tell if this screw hole is original.

 

There is a lower plate and an upper plate that the points are mounted on. The plate is held in place by the two long screws at each side of the housing.

 

I also provided a few photos of the rotor. I don’t know if this is an original rotor. It’s about 2.0” long.

 

Thanks for your timing information. From what I can tell my settings when the car was running, before I removed the SG, are very similar to your settings. My points were set at 0.018 and the car seemed to run good, Just got a dwell meter so I don’t know what the dwell setting is. Maybe I don’t understand, but I am not sure the value of measuring the dwell if the dwell setting is an unknown and will be specific to the car’s worn lobes...

 

 

 

 

 

 

 

 

 

 

 

Edited March 3, 2021 by KEK
Add photos (see edit history)

[Hubert_25-25]

Ken, 

   Thanks for the photos.  Good to see photos of a modified distributor.  Nice to make a hidden improvement.      Hugh

[KEK]

Hugh -

Your welcome. It looks like an easy modification if you can find the same points or a set that has similar dimensions. Just let me know if you need any other measurements or photos - Ken

[Robert Engle]

One final point, the reason to set to maximum dwell is to get maximum saturation of the coil for a hot spark.  If the points opening is too small, you will get arcing and burn the points. in the early days, mechanics did not have dwell meters.  feeler gauges would get the setting that doesn't burn the points.

 

I us a small battery that is for the emergency brake activation on my trailer.  They cost about $8.00

 

Bob Engle

[Old buicks 2]

I have a very ample supply of those points and rotors that KEK is showing in his pictures.All point sets and rotors are NOS.    tsvanmeet@gmail.com  or

 

402-359-5762

[KEK]

Yep those sure look the same points as what I have. I saw other holes in the breaker plate that were not being used so I assumed those hole were for the original points. Also these points look far better quality than original Model A points that I am familiar with so I was thinking they were more modern. Have you tried taking those NOS points to NAPA and check if they have anything similar?

[KEK]

Bob -

 

My dwell meter has an internal 9v battery so I don't think I need and external 12v to supply power to the meter.

 

An interesting point you implied is that the coil saturation increases with smaller point gap. Therefore there is an inverse relationship with point gap and dwell. I.e. smaller point gap more dwell. Since we don’t know what the correct dwell setting is for these worn out cams (see earlier discussion) then why not just set the points to the closest setting that wont burn them? Wouldn’t this be the maximum effective dwell that can be used. In your experience what is the smallest point setting that would be safe? - Ken

[Old buicks 2]

A lot of car guys tell me that new points from most auto supply stores today are not of the quality that the older points are.   I recently have a farm  tractor restorer order 50 sets of the NOS points in the picture because of poor quality from modern supply houses.

[KEK]

I went to NAPA and they don’t stock any points like the ones in the photo. I think if you want to use modern points you would have to modify a set that is close to the design of the original.

[KEK]

Hi everyone -

 

Finally got a dwell reading. I had to return the Cen-Tech meter to HF as it didn’t work. Then borrowed meters from 2 friends and those didn’t work either. Finally sourced a vintage KAL dwell-tach meter model 2020. Geez I guess it was worth it as I finally have a working meter. Here is what I found out;

 

Dwell - 42 degs. 

Point gap - 0.019”

The meter indicated points resistance 1/2 of full scale. Not sure what this means? 

Timing half way between the 7 deg and the 1-6 line.

 

AC spark plugs C77L (not sure if these are the correct heat range)

Spark plug gap 0.025” (as per shop manual)

 

Marvel carburetor Model 65-10 0

Fuel level set 1/8” below LS jet (0.925” below top of bowl).

Fuel valve opened one full turn in line with notch.

Air screw set so air valve is 1/16” to 1/8” away from wall (opened by gravity - no spring pressure). I can’t set the air valve flush with the ratchet set spring because I dont think I have a stock air screw. I think my dad made this one using a Master air screw as a guide. He had several examples of a Master air valve but no standard air valves. The standard air valve is a smaller diameter than the master air valve. See attached photo. I would be interested in purchasing a stock standard air valve if anyone has one for sale.

Air spring is 1-1/2 inches long.

New Venturi

Tail clearance set at 0.03”. This is twice the specified gap in the manual. I wanted to set the gap less than the spec but I dressed up the air valve a little bit and accidentally took too much off.

Idle speed 300 rpm fully retarded and 350 rpm fully advanced.

 

Observations;

The car runs real well. Idles nicely and doesn’t stall. I can set the idle down to 220 rpm but that seems a little low so I set it closer to what Hugh has his idle set at.  

 

The new Venturi makes all the difference in how the idle has improved.  It doesn’t seem like the larger tail clearance is causing me any problems but I don’t know what the symptoms of a larger than spec tail clearance.

 

A dwell of 40 degs seems high.  I was expecting a dwell closer to 30 or 35 degs based on earlier posts.  I really don’t want to mess with increasing my point gap to decrease the dwell because the car seems to run so good.

Not sure what the impact is of the high resistance in the points?  Do I need new points?

 

What spark plugs are recommended to run with the standard.  Are the AC spark plugs C77L okay?

 

It also starts easily.  I follow the shop manual instructions to start the engine. Pull out the choke fully and press starter until it fires. Then set choke to 3/4 full and press starter again. When I follow these instructions the engine has started every time.

 

I appreciate any comments...

 

Thanks,

Ken

 

 

 

 

 

 

Edited March 26, 2021 by KEK
Add photos (see edit history)

[Bloo]

If the points resistance is high, it could weaken the spark. You could drag a tiny file over them, but don't overdo it. One scrape ought to do the trick. If the car runs fine I wouldn't worry about it.

 

Regarding dwell meters.....

 

Dwell is the number of degrees that the points are closed, charging the coil. So, a wider points gap is less dwell, and a narrower points gap is more dwell. The gap will get narrower and the dwell higher as the rubbing block wears.

 

Since there are 6 lobes on a 6 cylinder distributor cam, 360/6=60 degrees. The distributor fires every 60 degrees of distributor rotation. If the points never opened, that would be 60 degrees of dwell or 100% "on" time for the coil. If the points never closed, that would be 0 degrees, or 100% "off" time for the coil. 30 degrees dwell would be 50% "on" time.

 

The reason I bring this up is that many dwell meters and analyzers cannot deal with 6 volts correctly if at all. When auditioning a dwell meter, set for 6 cylinders on a 6 cylinder car, points closed should bring the needle to 60 degrees. and points open should bring it to zero degrees. Some dwell meters have a knob to adjust. If it won't do this, or it's backwards, the readings are going to be wrong.

 

EDIT: KEK I misread your post the first time, so maybe I didn't need to type part of that. Glad it's running well.

.

 

Edited March 27, 2021 by Bloo (see edit history)

[KEK]

Hi Bloo -

 

Thanks for the tip on how to check to see if my dwell meter is operating correctly.  I never thought of that; to open the points and see if it is reading 0 and close the points to check that it is reading 60. Great idea.

 

It seems to run well with the high dwell of 40 degs so at this time I don’t think I want to mess with the point gap as difficult as it is to set unless I have to.   If the coil charges when the points are closed will too high of a dwell overheat the coil or somehow damage the coil?

 

Ken  

[Hubert_25-25]

Quote

 

Ken, 

      Here are some replacement numbers for your air valve adjuster.

Master   Standard

1.194 = 1.150

1.535 = 1.765 in the center, and 1.600 along the wall.

1.920 overall length for both

.383 = .105

.824 = 1.040

.906 = .865

 

So the air valve adjuster is the same overall length, but the Standard has more threads on the barrel.  The depth is what is important then.  The standard has a taper deep inside to keep the spring in the middle.  So the overall depth of 1.765 is .23 inches deeper than your 1.535.  For a Standard, the air valve is approximately at the end of the adjuster stick.  If you use a Master air valve adjuster, it should sit past the end of the air valve stick .23 inches to maintain the same pressure on the spring.   That looks like about what you have given that the part you adjust is 1/2" wide and you are just short of the very end by just under half the distance.  

 

   Regarding dwell.  My dwell meter like yours reads outside the 30-35 degrees that I was expecting to see.  My .19 is 27 degrees.  If your .19 measure 40 degrees, then that is your reference point for knowing where to set new points using that dwell meter. Now you have an easy clip on method to see if your points are worn.  

My meter has a "point condition" setting as well.  Supposed to read good or bad, but it just vibrates the needle.  

 

I have not run those plugs you have.   I opened my plugs up to .030  I have been running old Champion 3 com plugs.   The plugs you can buy now are Champion W89D.  

 

You could put some solder on the venturi pretty easily to build it up and then refile it?   

 

Glad that your Buick is running smoothly.  

 

Hugh

Edited March 27, 2021 by Hubert_25-25 (see edit history)

[KEK]

Hi Hugh -

 

Thanks for the measurements on the standard air valve. I will look for a standard valve with those dimensions. I could try to carefully drill out the center of my valve and increase the depth by the 0.23” which would leave about 0.16” of brass at the end - not a lot. The engine does seem to run okay with the home made air valve sticking past the adjuster spring by about 0.23” so a replacement standard air valve will only return it to original condition and make it easier for someone else to set it in accordance with the shop manual.  I have had it out a couple times for a few miles test run at 35 mph and stop and go traffic and no problems so far.  It’s sure nice not having to worry about the engine stalling out on me any more.

 

Good idea about adding solder to the venturi and then dressing it to spec. I actually removed too much material from the air valve when I dressed it so I was thinking I could replace the air valve and that would bring it back into spec.  But the engine runs so well I am not sure it would be worth messing with.  It seems like once the engine fires up the tail clearance would increase slightly so the amount of tail clearance set at spec should be negligible. And even more negligible at higher rpm. Am I thinking about this correctly?

 

The reason I was asking about what spark plug you are running is because mine look a little black around the edges.  I am pretty certain that I am not running too rich because if I lean out the carburetor any more it has no power or doesn’t idle correctly.  So I was thinking my plug heat range may not be correct.  Would increasing the gap from 0.025” to 0.030” help?

 

Ken

[Larry Schramm]

The C77L spark plugs are on the hot side of normal I believe.  The C just stands for a commercial plug.  Really no difference from 77L plug.

 

If your dwell meter has a voltage input, just connect it to a 12 volt battery and that should have you running fine.

[Terry Wiegand]

In a C77L plug the L stands for LONG REACH.  This means it reaches farther into the cylinder cavity.

 

Terry Wiegand

South Hutchinson, Kansas

[KEK]

Larry -

 

My vintage dwell meter has a red clip I attached to the terminal on the distributor and a black clip I connected to ground. No other inputs.  

 

I checked the meter as Bloo suggested and found when the points are open the meter reads 27 (should read 0) and when the points are closed it reads 60. So if I normalize the 27 reading to zero then there are 1.8 degrees per meter unit reading (60-27 = 33 and 60/33 = 1.8). The meter reading I got when connected to the distributor and with the engine running was 42. This equates to a dwell of 27 degrees (42-27 = 15 and 15x1.8 = 27).  

 

This is consistent with the 27 degrees dwell Hugh measured for a point gap of 19 on his 25 standard.  My point gap is also about 19 and I get a dwell of 27.  That’s good to know so if I ever get a dwell meter that actually works I can set my points to a dwell of 27!  The Buick shop manual says to set the points to 0.018“.  So if I decreased my gap from 19 to 18 then my dwell would increase closer to the 30 - 35 degrees that we expect.  I am not going to fiddle with my points because I am happy with the way it is running.

 

Are the Champion W89D spark plugs long reach like the AC plugs?

 

Ken

[dibarlaw]

Yes Ken the Champion W89Ds are longer reach. That is what I am running in my car now.

   

The original S.A.E. (7/8 Thread) Long, AC Titans. Had a greater reach than the commonly found available 3076 Motorcraft or Autolite plugs. The AC 77L was the go-to replacement plugs untill they were discontinued. The motorcraft Autolite also had a 3077 long reach that has since been discontinued.

The Champion W89D has the longer reach in electrode and insulator. Not in the body jacket as in the older Titan style.

 By the 1930s AC had reduced the vaiations of their offerings. At least in the 1934 ad below. Listing a cheaper TITAN 30 cent multipurpose plug for 7/8 thread as #1.

 Also a "Universal" 7/8 plug Type AA at 40 cents. 

Then "Original equipment Type" Type A 7/8 regular and Type B 7/8 Long.

 

[KEK]

Larry -

 

It is really neat to see this old advertising. Thanks for sharing.  

 

Did you see the H14 spark plug with the primer valve advertised on the last page of the Salt Lake Hardware flier?   I have never seen anything like this before but apparently you could add fuel directly to the combustion chamber with this fancy spark plug! 

 

I also see that they were selling aftermarket air cleaners for the Buicks. That brings up a question I have been wanting to ask.  My engine doesn’t have any air cleaner.  It’s a new rebuild engine and I don’t want to damage it by running without an air cleaner but not sure if I need to add one.  I certainly don’t drive it much and the roads aren’t dusty as in the past.  Do you or others run air cleaners?  I appreciate any comments?

 

Ken

[dibarlaw]

Ken:

 So far I only run the air horn. I think Hugh did work up a filter unit. Some heavy duty Lawn tractor/equipment filters could be adapted.

[Mark Kikta]

I found this chart somewhere that I use a lot.  I'm currently running Blue Crown 75-com plugs.

[Hubert_25-25]

Ken, 

   Thanks for getting another project of mine off the shelf and onto the car.  This is my replacement for the air horn.  The metal can that Larry showed in the advertisement is what was installed as standard equipment in 1926 when Buick went to triple filters (Air, oil, and fuel).  I used a piece of .025 aluminum sheetmetal to make an adapter.  Then I bought a UNI 601 1 3/4" x 2 3/4" x 6" air filter.  Around $15.  These have an internal wire spring to prevent collapsing.  The hose clamp barely fits, but it does, and I can still get to the dip stick.  With a little more effort, a person could likely make an elbow for the adapter and install the filter vertically.  Some people take these and soak them in oil, then wring them out before installing.  I just install mine dry.  K&N may have less pressure drop since it would be pleated. but then you for sure have to use an elbow to install it.  I just installed this 10 minutes ago, and I have not started the motor.  Uni sells this same green material in 1/2" thick sheet form, and I made removable air filter covers for my Jaguar AC pancake air filters and I have not noticed any change in performance with this material installed.  One other nice thing about this is that the original air horn makes it difficult to use starting fluid.  I use that sometimes if the car has been sitting for an extended period and I don't want to wear out the starter.   

 

Hugh    

[KEK]

Hugh - The UNI filter sock looks like an easy solution.  I am going to order one today.  Thanks for the information and the dimensions for the adaptor.  What is the hole in the adaptor at the 5 o’clock position for?  Is this for the screw to secure it on the carburetor and the hose clamp used just to secure the filter on the adaptor?

 

Mark - Thanks for the spark plug chart - very useful.  I see that the Blue Crown 75-com plugs you are using is the equivalent heat range as the AC 77L plugs I am using and they are at the upper end of the heat range as Larry mentioned.  I don’t see that increasing my heat range will eliminate the black carbon I am seeing on my plugs.  I am thinking now that the carbon deposit may be due to a rich idle but at higher rpms they may run cleaner.  I need to test this by running the engine down the road at higher rpms (35 mph) and then shut off the engine and pull a plug to see what it looks like.