1938 Buick Century Timing Marks...

[philipj]

Does anyone have a clear photo of the flywheel timing marks? I warmed the car up, hooked the timing light and... Nothing. Don't have the best eyesight in the world, but thought I might be close to it... I am guessing the car is idling about 600 rpm. If I had some volunteers I might roll the car back and forth until the mark is found so I can use a paint pencil, and then try the light...

[Ben Bruce aka First Born]

philip, best way is down and dirty.  There is a flywheel cover between the tranny and engine. Six bolts, I believe. Remove that and the front side of the flywheel cab be seen. Rotate the engine, using a large flat blade screwdriver ,or some such , to pry on the flywheel teeth until the timing mark can be seen. Us a fine point paint brush or a paint "pencil" and mark them.

 

  Ben

[MCHinson]

This is what the marks look like. This photo was taken with the flywheel access cover removed.

[Gary W]

 

I used this gold paint, thinking the timing light would really illuminate it.  It doesn't.  Use a good white paint to highlight the marks and run a line like Matt did above.

[Daves1940Buick56S]

This may be heresy to some, but...it is difficult to get in really close to see the mark for me, just in that wrong distance spot for my vision/glasses. So i carefully statically set the engine to the ADV line with #1 in firing and got some white touch up paint, painted a mark on the timing chain cover and a corresponding mark on the damper and another at TDC. Now I can time without having to remove the little cover. Plus it makes it easy to check out mechanical and vacuum advance operation.

 

Cheers, Dave

[philipj]

Great tip regarding the lower flywheel bottom cover, always forget about that... The idea of a timing mark on the front cover and damper is not bad either, certainly easier to see thank the flywheel mark... Thank you. First I will paint a mark and see what happens if that fails I  will turn to the static timing which it is not easy for me either. Not used at all with these overhead straight eight's... Certainly not like a flat head four cylinder so easy to get around to!

 

Since Dave brought up the mechanical advance operation, what is the best way to check that it is A-OK?

[Daves1940Buick56S]

E-Z. Look in your shop manual, p. 12-18, fig 12-20. The distributor advance curve is there.

 

1. Disconnect and plug the vac advance.

2. Hook up a reliable tach.

3. Get a good timing light that has the adjustable delay, set it to zero.

4. Set idle speed to 400 rpm. Note the base timing, spec is 6 deg.

5. Increase idle speed and take data points every 200 rpm or so. For each point note how many degrees of delay have to be added to the timing light to bring the timing mark back onto the mark

6. Using the base timing, add the delays and plot a graph using Excel or similar and see how it lines up with the one in the book.

7. Don't forget to hook the vac advance back up!

 

Cheers, Dave

Edited April 28, 2018 by Daves1940Buick56S (see edit history)

[DonMicheletti]

One reason you may not be able to find the timing marks with a light is it is possible that the flywheel had been removed and not put back in the right orientation.

There are 6 bolts holding the flywheel on and it is an 8 cylinder car.

That means that there is one right way to install the flywheel and 5 wrong ways.

When I got my Roadmaster the flywheel was on wrong and I just timed it by ear - very old school. The first clutch replacement I installed the flywheel correctly.

 

Method. Get the engine running and advance the distributor a little at a time until it pings on a test drive on hard acceleration. When it pings, just retard it a bit until it doesnt ping.

 

I didnt have no fancy timing light whan I was a kid!

[MCHinson]

Another tip for using a timing light on your 6 volt car is to use a 12 volt source of power for your timing light. It makes it much easier to find the mark with the brighter light. I was checking my 1938 Century project today and could not see the mark with the light attached to the car's battery. I brought a 12 volt jump box over and connected the timing light to it for power and had no problem seeing the timing marks.

 

As far as checking the vacuum advance, I simply reached across the engine bay and accelerated the engine and saw that the timing marks moved, so I take that as sufficient evidence that the vacuum advance is working on my 1938 Century project.

[Daves1940Buick56S]

Matt,

 

What you describe will tell you if the centrifugal advance is OK, or at least functioning, but not necessarily if the vac advance is working. The quick and dirty way to do that is to snap the throttle open and closed while observing the timing mark. It should rapidly advance several degrees and then return to normal. Of course you have to be able to see the mark, which is one of the reasons I painted marks on the damper.

 

Cheers, Dave

[MCHinson]

On 4/29/2018 at 1:13 PM, Daves1940Buick56S said:

 It should rapidly advance several degrees and then return to normal.

 

That is what I was expecting and observed so that was my quick test. It seems to drive fine with my limited driving so far, so I think it is OK.

[philipj]

Today I removed the bottom flywheel cover and marked the flywheel... After the car warmed up I placed the timing light, only to see that it was not far off... Just a little under the mark. After a few revs, I pretty much placed the mark dead on and the hiccup is almost gone... Otherwise, the car is very smooth at idle. While doing this you could also see the timing mark returning to normal, so I could say that the vacuum advance is probably working...

 

I can still feel a very slight blip around 35mph, but it seems much smoother. I have been playing with the mixture screws as well. The car seems to like it around 1.5 turns, but felt it was using fuel like a goonie bird... 1/4 of a tank in about 25-30 miles seemed excessive, but I was also idling and tinkering with the carburetor for a while... 

 

How many miles per gallon do you guys get? I probably used 4 gallons of fuel!...

Edited May 2, 2018 by philipj (see edit history)

[DonMicheletti]

You probably cant expect much more than 12 mpg if that. The tinkering can skew your fuel use.

I always start out with 1-1/2 turns on an idle screw on a new carb or rebuild. I never pay much attention to where the adjustment ends up once the car is running fine.

I expect both screws to be in much the same position. If I get a significant difference between the 2 I start digging to see what might be a problem.

[Ben Bruce aka First Born]

phillip, you are aware the screws you are fiddling with are ONLY for the idleing circuit.

 

 Another way to set the timing is with a vacuum gauge.  Hook it into the manifold vacuum and adjust for highest vacuum.

 

  Ben

[philipj]

Hello Ben,

 

Thanks for pointing that out... I was not aware that the mixture screws affected only the idling circuit...Got a lot to learn!..;(  I also do not own a vacuum gauge but have heard it is the best tool to have if you have a vehicle with a carburetor... I would also need a tutorial on that I'm afraid.

Now while on the subject of timing, do these engines favor the timing being slightly retarded, or have to be right on the spot? I have a timing light with a dial that is set up to Zero when in use for this, or should it be set at 6? Now I am questioning everything!... 

[Ben Bruce aka First Born]

I always liked at least the 6 that Buick called for.  

 

  Ben

[philipj]

I went back to the timing light with the dial on 6° and believe it or not, it did not change one bit! I was surprised, the car was fully warm after a ride to the gas station! Every other day I have to cough up 20 bucks to ride for a while... Darn, I really want to get this tuned up! Need to get a hold of a vacuum gauge and learn how to use it!

[RiKi5156B]

I looked at that timing mark when I was building my 248 twin carb and said to myself,heck with that. I got #1 TDC marked and graduated on the balancer and marked TDC on the timing chain cover. Just like a MODERN car!?