1941 Tming Adjustments and More

[Guest EdMinster]

Hi I have a 1941 Buick Special 8. It has a 248 inline 8. I just got my radiator back and have been trying to get the car running. We were trying to figure out the timing but I don't understand how to do this with out the "degree scale" on later cars (excuse my lack of proper terminology). There is a mark or indentation on the flywheel but nothing to measure it against.

As well I have been unable to find what the timing should be set to. All I can seam to find is "BTDC or as marked) I'm not fully sure I understand this. What mark are they referring to and what does it line up with?

The last thing we were having trouble was the dwell. I found something that I think was saying between 21 an 30. I not fully confident it that value though.

Below are some pictures. I am also in the process of converting to 12V. This is just a temporary setup while we are trying to get it working.

There are more pictures at

Edward Marciano's Photos - 41 Buick | Facebook

Thanks for all your help guys

Ed

Edited July 22, 2009 by EdMinster (see edit history)

[Ben Bruce aka First Born]

Welcome, Ed.

There is a mark at that btdc on the flywheel. It is about 1/8 inch wide, and looks like screen wire pattern. You may have to access the flywheel from below to find it and mark it with crayon or chalk or whatever you choose. Anyway, this is the btdc mark referenced. Then looking at the flyweeel, clutch housing near the starter there is an opening about 1 1/2 inch square. May still have a pry off cover. There is an indention at the top edge. This and the mark on the flywheel are the timing marks. Hope this has helped.

Ben

[Barney Eaton]

When in dought, use a vacumn gage.

Start by getting #1 plug to fire at TDC. With the engine running, advance the timing at idle until you get the highest vacumn reading.

This may only be a starts but on your low compression engine this should be pretty close to best overall performance.

[Guest EdMinster]

Thanks for your help guys. I will definitely give the vacuum a try for tuning. I Just want to get it close to the mark then go from there. I am slightly confused where you (First Born) are talking about.

Here is what I was thinking when I said flywheel

The marks on the right are arbitrary marks we were trying to work off of. The mark to the left I what I was thinking of but I don't think this is what you mean is it?

I found the hole over on the clutch cover.

I assume this is the mark you are talking about on it.

Judging by this when you say flywheel you mean the plate that is visible through that hole not the "main pulley". If so I'm not sure I understand how I access that plate to find the mark. Would I be able to find it by removing the starter and use its hole or is there another method.

Thanks again for your help and advice

- Ed

[Larry Schramm]

I prefer using the vacuum gauge when you can not find the mark, but after you get the maximum vacuum, back it off just a little bit so you do not get spark knock. You can try maximum vacuum, but may end up with the engine knocking on load or acceleration.

[Ben Bruce aka First Born]

You found it , Ed. Now turn the engine until the BTDC mark appears in that window. It is stamped into the flywheel, which is what you are seeing through the window. As I mentioned, I like to mark the mark with a piece of chalk. Also the indention at the top of the window. Then when you use the timing light, they show up real well. Then, with engine running, timing light attached to #1 plug, aim the light at that window. Adjust timing by teisting the distributor until both marks are aligned.

Larrys idea of a vaccum gauge sounds good, also. Have never tried that, but will.

Good luck

Ben

[Thriller]

Ed,

I have no knowledge to add, but wanted to wish you luck from a fellow '41 Buick owner. The single carb setup is actually relatively rare - it was only on the Special series and many of them were ordered with the optional compound carburetion.

[Joseph P. Indusi]

EdMinster:

The mark on the flywheel is not easy to see unless you paint it with a white touch-up brush or white chalk. You need to get under the car and remove the lower bell housing cover, about 6 bolts. Then rotate engine until you see the mark. It is quite small and near the edge of the flywheel ring.

Joe

[Guest EdMinster]

Hey guys thanks for all the help! I got the car started to day only having to turn the key (didn't need to pump the pedal or any thing). Now I just have to fine tune it all. I would never have found that adv mark on the flywheel if it were not for you guys. I could barely see it when I found it.

Once I get the engine all tuned I was planing to move to the brakes. I have been looking around for interchangeable parts but haven't been too successful. I would love to convert the front drums to disc brakes without changing the front end. Ideally I would like to just remove as little as possible. I still want to use the same shocks and stuff but would like the braking power of disc. The disc are not necessary for me but would be nice. I was just wondering if you guys know of anything I could pull off another car or something.

To go along with this I was looking at moving to power brakes. Do any of you guys recommend a car that I can pull off of or buy?

Thanks again for you help.

[Bill Stoneberg]

The drum brakes, set up correctly, and working correctly, will stop your car just fine.

This is providing you dont tailgate and keep a reasonable distance between you and the car in front of you. I drive a 1947 at freeway speeds and dont have any issues.

Disk brakes are going to be a custom job and will probably cost you an arm and a leg. You will have to replumb everything and figure out what do do with the splindles. Lots of work for not much reward.

They work fine on street rods where you put a clip on the front end but I would keep this one original.

[Patrick W. Brooks]

Hello: The timing must be right for the car to run at speed. At idle is another matter. Notice that there are two marks on the flywheel. One is the TDC mark and just beyond it is one which says that it marks 6 or 8 degrees off Top Dead Center. I believe the small engine is 8 degrees and the large is 6 degrees, or the other way around. The flywheel marking will tell you without my checking further. Remember that the explosion in the combustion chamber does not occur when the piston is at the very top of the cylinder. It occurs a few degrees off TDC so as to reduce the stress to the bearing and crankshaft. Do not mark the TDC marking as your timing light must show the 6 or 8 degree marking to time the car. The TDC marking is most helpful to be certain the distributor is set either on the 1st or 8th cylinder at TDC as it shows when both the 1st and 8th pistons are at Top Dead Center. Mark the 6 or 8 degree marking on the flywheel and not the TDC marking. Let me know if I can answer questions. Thanks, Patrick W. Brooks

[Grandpa]

I would like to offer a comment on the point at which the spark plug fires: The correct ignition timing has the spark plug firing before TDC in order to allow for the prorogation time of the explosion. If the spark plug firing is set too early before TDC, a pinging will occur, with the possibility of bearing damage - If the spark firing is set after TDC, there will be a power loss, reduced mpg, as well as possible damage to the exhaust valves.

Grandpa

[Patrick W. Brooks]

Good Morning All: Sorry I haven't had time to check the Buick web for a week but wanted to say Grandpa is absolutely correct. Took the time to check my shop manuals for 1949 and 1952 to see the wordage used by Buick to describe the mistakes which can occur with timing. It is important to note that the prewar manuals simply are not as complete as the straight 8 manuals printed for the years after the war. I always check both when doing work on any prewar Buick. The engines are basicly the same even though there were improvements. With some exceptions, the manuals after the war are on point for the prewar straight eights and much more explanatory. My 1949 and 1952 manuals use the exact same wordage. What I have typed below is found in Chapter Ten (IGNITION SYSTEM, 10-47) and the flywheel markings are pictured there and explained while not explained nor pictured in my 1940 manual. The important statement is as follows:

Section 1047 in both manuals:

" The timing mark stamped on flywheel is 1/8 inch wide, knurled, and painted yellow. The 1/8 inch width provides a tolerance of one degree when setting the timing. On Series 40-50, the timing mark is stamped "ADV 4 degrees" and gives a timing setting 4 to 5 degrees ahead of upper dead center. See figure 10-78. On Series 70, the timing mark is stamped 'ADV 6 degrees and gives a timing setting 6 to 7 degrees ahead of upper dead center. (UDC stands for upper dead center)

The upper dead center mark on flyweel, stamped "UDC 1-8", follows closely behind the ignition timing mark as the flywheel rotates. See figure 10-78. THIS MARK MUST NOT BE USED FOR IGNITION TIMING."

For anyone working on a prewar Buick, including your mechanic, I would recommend buying a post war manual. My favorite is the 1948-1949 manual or later. Remember in 1953 the Special was the last straight eight and the 1952 manual covers the 1953 straight eight and the 1953 manual covers the new V-Eight. Hope this helps.

Thanks, Patrick W. Brooks

[Marty Roth]

I drive a 1934, and I do a LOT of touring -- forget trying to adapt power brakes -- my car doesn't even have hydraulic brakes, but the mechanical brakes, adjusted properly, do a flawless job of stopping the car. (Yes, I realize that this car has a vacuum booster !).

My '34 drives like a modern car: easy steering, easy handling, good brake action, and it looks pretty classy too. Anyone who has seen it on Glidden or Heritage or Western National Tours will probably agree that it likes to get on down the road.

[Vic G]

Hello,  I just wanted to say thank you to all,   by reading most of your  post and comments  I don't have to ask many questions. As my boss just perched a 1941 Buick Special  with dual carbs. 

Before  and after I tuned it up it has a bad ( I don't know how to explain it )   but it's like it has an on and off switch at half throttle  but if you go to wide open throttle it don't miss a beat. Now if you go to wide open from an idle it's has no problem. Does anybody have any info for me ?   Thanks Vic

Edited June 2, 2019 by Vic G (see edit history)

[Guest]

 

5 hours ago, Vic G said:

Hello,  I just wanted to say thank you to all,   by reading most of your  post and comments  I don't have to ask many questions. As my boss just perched a 1941 Buick Special  with dual carbs. 

Before  and after I tuned it up it has a bad ( I don't know how to explain it )   but it's like it has an on and off switch at half throttle  but if you go to wide open throttle it don't miss a beat. Now if you go to wide open from an idle it's has no problem. Does anybody have any info for me ?   Thanks Vic

Welcome, I am sure everyone here appreciates your thanks but you would be better served if you started your own topic with your questions.  Then nobody gets confused.

[Lawrence Helfand]

My 41 factory timing specifications presume you are using fuel with the octane rating of 1941 which was under 80. Many cars including my old Toyota had an advance adjuster on the distributor for the sole purpose of ignition advance or retard depending on octane of fuel. If you set your timing to prewar factory recommendations your ignition will be retarded and you will run a little hotter and use more fuel. I use an 86 octane non ethanol regular and have advanced my timing quite a lot and to excellent effect. I suggest advancing as much as possible without inducing pre ignition under load which will become apparent by accelerating in top gear from low speed with full throttle. Using vacuum as an indicator takes octane into account in real time and will be a better path to good timing then factory flywheel settings which are no longer relevant unless your using 76 octane gas. 

[valk]

Interesting. Has anyone else advanced their timing? I've also heard the argument that the manifold heat control valves and the rear carb damper are no longer needed due to improvements in fuel. My '41 doesn't have any of these and it runs great (now). 

[Matt Harwood]

On 7/20/2009 at 7:14 PM, Barney Eaton said:

When in dought, use a vacumn gage.

Start by getting #1 plug to fire at TDC. With the engine running, advance the timing at idle until you get the highest vacumn reading.

This may only be a starts but on your low compression engine this should be pretty close to best overall performance.

 

This is how I do it. Easy!

 

2 minutes ago, valk said:

Interesting. Has anyone else advanced their timing? I've also heard the argument that the manifold heat control valves and the rear carb damper are no longer needed due to improvements in fuel. My '41 doesn't have any of these and it runs great (now). 

 

I've advanced mine a bit past what the vacuum gauge says but I can't say I can feel much of a benefit. I've finally got it running right again so I don't want to mess it up. You can advance it a bit and tune it by ear and see if you feel any seat-of-the-pants difference, but it won't necessarily be faster, just a bit better throttle response.