TOP DEAD CENTER Ford 1946

[Bruce Lancaster]

OK...TDC cannot be found directly closer than 2-3 degrees due the the DWELL at TDC of long rod, offset engines. Dial indicator, moving oil, whistles, eyeball all get you only in ballpark, probably as good as an average factory mark but better ways are easier.
Commonest easy ways head on or off are versions of INTERFERENCE method.
Off, strap and bolt stops piston a ways down the hole on both sides of TDC. Mark both places and measure spot on pulley halfway in between, very accurate.

Someone pointed out to me the offset principle used in Fords (DeSaxe system, described waaaaay beyond my math education in a Ford engineering book I have, means rate of crank motion vs. rate of piston motion actually differs between UP and DOWN...a mind-blowing concept, but you can ignore it as difference is in the gnat's eyelash range.

A consequence is that head OFF method allows measuring farther down the hole and that is slightly more accurate, but I thing the inaccuracies are probably smaller than you could approach making your marks.

Head ON a fat zip tie allows you to stop the piston the thickness of the buckle down the hole. The strap allows your apprentice a decent chance to hold the thing through the plug hole and keep it in the same place for both bumps. Fattest object you can get in there and hold against the far wall so you can repeat is the best. Obviously range of thickness possible is tiny.

Turnit til it stops, mark, turnitaround the other way til it stops. TDC, theoretically slightly imperfect but way better than any other reasonable way, is half way between.
This way only takes a few seconds once you gather the gear...repeat it several times and be sure you find the same center each time. If you don't, find a steadier apprentice.

The first time I built a FH, I had a superduper ex-Wehrmacht dial indicator found in a German junk shop and a degree wheel. I carefully located TDC by the indicator and thought myself home free.

I stepped back and spun the thing a couple times watching carefully, and discovered to by absolute uncomprehending horror that the indicator with its zillionth of a millimeter reading had not even a trace of movement for well over 2 degrees! I had absolutely NO clue, and had to go with good enough around the middle of that. I had to slink away with my tail between my legs and worry about it for a long time.

Twenty years later...I found Smokey Yunick explaining what had happened to me in his wonderful book. There it is. Long rods in relation to stroke and crank/piston offset both contribute to this totally unexpected effect.

[Bruce Lancaster]

Remember when adjusting timing by vac gauge...you are moving not only the idle setting but the ENTIRE CURVE, add in 4 degrees and your timing will be 4 degrees more advanced at all points in the curve. This may or may not matter...we are dealing with really low compression and running on gas that is probably twice as knock resistant as what was around in 1946...
Remember also that you have a vacuum brake as an adjuster for the RATE of advance.
On that...loosen the lock nut, then run the adjuster bolt all the way out until you hit a stop...do NOT twist hard or you will unseat the spring. (Actually, FIRST take the thing apart at the BIG nut and be sure piston is not stuck, then clean and lube it.)
Once all the way out, road test under various acceleration loads...if it pings more than a trace it should be screwed in minimum to end the pinging. This is primarily an adjustment for really horrible depression era/wartime gas that you wouldn't use in a lawnmower now, and adjustment all the way out is usually fine.

[Old Henry]

Today I discovered yet another benefit of adjusting my timing to maximize my vacuum.

We got the first rain/snow we've had here in Utah for almost two months. Unheard of. As I was driving "Old Henry" through the falling snow with the vacuum operated windshield wipers on I realized they were working better, had more power, and were moving faster. I wondered why. Then I remembered having advanced my timing all the way to maximize my vacuum. There you have it. One more benefit - better working vacuum operated wipers!

[Harylufa]

Dear Bruce and Henry!

My God a lot of Information! With my head off I really set TDC?

I did this!!! By walt Dupont--me

If you've got the head off I'll tell you how to do this real simple. First make your pointer where you want it on the front cover. I use the bottom bolt right side of the front cover. removed the bolt, take a longer bolt and cut the head off, now grind the head of the bolt to a point, now screw a nut on the bolt up to the end of the threads, screw the bolt in with your finger and then tighten the nut. Now you have a pointer pointing right to the edge of the pulley. NOW, with the head off, take a thick piece of metal, at least 1/4in. thick and about 3/4in. wide, and about 4in. long. Drill a 7/16 hole on the metal slide it down over a head stud so about 1/2in. is sticking over edge of the piston, hand crank the engine over in one direction untill the piston hits the metal, NOW make a chalk mark on the pulley where the pointer is, NOW crank the engine over in the other direction untill it hits the melal, make another chalk mark. Now the 2 chalk marks should be about 1/2in. apart, in the center of these 2 marks is TDC. Simple. Walt

I think It alright now, Am I right? ONE QUESTION? my car say It has to have 4ºBTCD am I right, now how I apply this?

Mark is done in pulley, and now 4ºBTDC is 4,73 millimeter (Pulley diameter is 13,57 millimeter)

Must I do another mark that would be 4º BTDC???

SEN 4º=X/6,785 (RADIUS)

X=SEN 4º x 6,785 = 4,73 millimeter


Can I use a timing light NOW? Please, tell me how!!!

I really thank all for great information!!!

harylufa!

[Bruce Lancaster]

More degrees needed! Figuring out and measuring the width of 4 degrees will drive you mad.
Get: A piece of cardboard, a compass, and a protractor.
Measure the diameter of your pulley at the point you will be marking it.
With compass (find a 12 year old who is taking Euclidean geometry, trade him a cookie for his compass) draw a circle on the cardboard the diameter of yor pulley and from the same center another circle outside that.
Use protractor, draw a line out and more lines at intervals. I would mark 5 degree segments out to about 40, then mark that forst segment into single degrees. Or...you can estimate pretty well within 5 degree blocks.
Cut out the inner circle you drew, slide the remaining circle over the pulley. You can even cut it to get past belts.
Hold first line at your TDC mark, punch other marks as needed. Give the 12 year old his tools back. Done.

[Bruce Lancaster]

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Now...go back to that vacuum brake...you want to be sure you are not running retarded because brake is tight or stuck, and then compensating by jacking up the static timing...that is a mechanical process called chasing your own tail!
Get everything working, THEN experiment to find what timing your distributor likes...messing with the timing is a nice cheap, easy way to find your car's zone of happiness. Good timing curve makes a solid difference you can feel.
Stock '46 curve is usually not bad at all, and is meant when brake is off to start advancing right above idle, them advance quickly up until about 2,000...easy to look at once you have enough degrees!

[Mike in AZ]

great thread...and you can probably find a protractor that is close to diameter of the pulley making it easy to figure out the degrees..i think...lol....thanks for the great answers to his questions.....Mike

[Ol' Ron]

Atta boy Bruce!! With our system we're running 30 degs total in cruise. This drops off to 22 mechanical at WOT. 8:CR reg gas and no ping yet? so we;re looking for more. On the 11A you can grind the adv slots to give more advance at Hi vac. But the piston has to drag the adv weights or you get erratic operation. We keep putzin.

[peewee2you]

I would remove the dizzy cap, rotate rotor to number one vicinity on dizzy, remove spark plug on #1 piston and insert screw driver in hole where spark plug was removed with some one else using a extension and socket on crank pulley bolt rotate in rotor rotation direction while feeling the screw driver on top of piston #1 you should be able to feel the up and down point pretty close letting you know your at the top.

[Harylufa]

Originally Posted by Ol' Ron

Atta boy Bruce!! With our system we're running 30 degs total in cruise. This drops off to 22 mechanical at WOT. 8:CR reg gas and no ping yet? so we;re looking for more. On the 11A you can grind the adv slots to give more advance at Hi vac. But the piston has to drag the adv weights or you get erratic operation. We keep putzin.

Dear Ol ron!

Can you explain what you wrote here in basic no abraviation, please, I think is important what you say! And I want to understand all of you, I learned English but is difficult for me Technical Words.

Thank you veru much.

Haylufa.

[Harylufa]

Originally Posted by Bruce Lancaster

More degrees needed! Figuring out and measuring the width of 4 degrees will drive you mad.
Get: A piece of cardboard, a compass, and a protractor.
Measure the diameter of your pulley at the point you will be marking it.
With compass (find a 12 year old who is taking Euclidean geometry, trade him a cookie for his compass) draw a circle on the cardboard the diameter of yor pulley and from the same center another circle outside that.
Use protractor, draw a line out and more lines at intervals. I would mark 5 degree segments out to about 40, then mark that forst segment into single degrees. Or...you can estimate pretty well within 5 degree blocks.
Cut out the inner circle you drew, slide the remaining circle over the pulley. You can even cut it to get past belts.
Hold first line at your TDC mark, punch other marks as needed. Give the 12 year old his tools back. Done.

Dear Bruce!

I will have to buy a compass, my boy is 4 years old, ja! and he will use it in the future.
you wrote (forst) I can no translate it. It is a great Idea compass!
I am trying to translate carefully many times what you say!

Thank you,

Harylufa

[Old Henry]

Originally Posted by Harylufa

Mark is done in pulley, and now 4ºBTDC is 4,73 millimeter (Pulley diameter is 13,57 millimeter)

Must I do another mark that would be 4º BTDC???

SEN 4º=X/6,785 (RADIUS)

X=SEN 4º x 6,785 = 4,73 millimeter


Can I use a timing light NOW? Please, tell me how!!!

I really thank all for great information!!!

harylufa!

Hary,

You already figured it out geometrically without any of the other suggestions given. At the diameter of of your pulley 4 degrees from TDC is, as you say, 4.73 millimeters to the side of it. If you have that marked you are ready to time the distributor with a timing light. Here's how you do it.

Hook the power wires for your timing light up to the battery being sure to get the right clamps on the right poles of the battery (red to positive, black to negative). Now clamp the pickup around the spark plug wire to the #1 piston that you used to find TDC. Loosen the timing screw/plate on the side of your distributor so that you can slide it to change the timing while the engine is running. Now start the engine and let it idle. Point your timing light at the new timing marks you have just made and see where the mark on your crankshaft pulley meets the marks on the engine. If the mark on your pulley is not right on the 4 BTDC mark slide the adjusting screw/plate on the distributor get it to match. Moving the adjusting screw/plate down (clockwise when looking at the front of the distributor) will advance the timing. Moving it up (counterclockwise) will retard it. When you get it just right tighten the adjusting screw and you're done.

That's all there is to it.

Good luck.

[Old Henry]

Originally Posted by Harylufa

Dear Bruce!

I will have to buy a compass, my boy is 4 years old, ja! and he will use it in the future.
you wrote (forst) I can no translate it. It is a great Idea compass!
I am trying to translate carefully many times what you say!

Thank you,

Harylufa

Hopefully, Bruce will not be offended at my attempt to translate what he said.

I'm not sure that the compass that you are thinking of is what Bruce was talking about. The word in English has two very different meanings. One compass is a small round container that has a magnetic needle in it that points north to navigate by. The other is the on like the letter V that has a sharp point on one end and a pencil on the other end. It is used to draw circles. That is the one Bruce was talking about to use to draw a circle the diameter of your crankshaft pulley.

Bruce's word "frost" was actually a mis-spelling of the word "first." Use the word "first" in the sentence in place of his word "frost" and you'll understand it better.

As I said before, Bruce's method is just another method of finding the various degree marks around your pulley which you already did by geometric calculation, that is, you took the diamater of the pulley (135 millimeters), multiplied it by pi (the ratio of diameter to circumference - 3.14) divided that circumference by the number of degrees in a circle (360) and multiplied it by 4 to get the distance of 4 degrees from TDC - 4.73 millimeters. Your method was much faster and easier. And, if you want other degree marks they are, as you have probably already figured out, 1.1825 millimeters from each other.

I'm afraid I can't help much with what Ol' Ron was talking about as I don't understand all of it either. I'm pretty sure that when he says: "With our system we're running 30 degs total in cruise" he's talking about total advance in timing adding the initial timing and the advance created by the centrifugal mechanism in the distributor controlled by vacuum at steady highway speed. When he says: "This drops off to 22 mechanical at WOT" I think he's talking about the portion of the total advance that is caused by the centrifugal advance mechanism in the distributor not including that set initially at idle. WOT stands for Wide Open Throttle. Beyond that, I don't know what he is talking about either. Hopefully he will enlighten us. It may have been jargon that only he and Bruce understand since he was addressing that message to Bruce.

[Harylufa]

Originally Posted by Old Henry

Hopefully, Bruce will not be offended at my attempt to translate what he said.

I'm not sure that the compass that you are thinking of is what Bruce was talking about. The word in English has two very different meanings. One compass is a small round container that has a magnetic needle in it that points north to navigate by. The other is the on like the letter V that has a sharp point on one end and a pencil on the other end. It is used to draw circles. That is the one Bruce was talking about to use to draw a circle the diameter of your crankshaft pulley.

Bruce's word "frost" was actually a mis-spelling of the word "first." Use the word "first" in the sentence in place of his word "frost" and you'll understand it better.

As I said before, Bruce's method is just another method of finding the various degree marks around your pulley which you already did by geometric calculation, that is, you took the diamater of the pulley (135 millimeters), multiplied it by pi (the ratio of diameter to circumference - 3.14) divided that circumference by the number of degrees in a circle (360) and multiplied it by 4 to get the distance of 4 degrees from TDC - 4.73 millimeters. Your method was much faster and easier. And, if you want other degree marks they are, as you have probably already figured out, 1.1825 millimeters from each other.

I'm afraid I can't help much with what Ol' Ron was talking about as I don't understand all of it either. I'm pretty sure that when he says: "With our system we're running 30 degs total in cruise" he's talking about total advance in timing adding the initial timing and the advance created by the centrifugal mechanism in the distributor controlled by vacuum at steady highway speed. When he says: "This drops off to 22 mechanical at WOT" I think he's talking about the portion of the total advance that is caused by the centrifugal advance mechanism in the distributor not including that set initially at idle. WOT stands for Wide Open Throttle. Beyond that, I don't know what he is talking about either. Hopefully he will enlighten us. It may have been jargon that only he and Bruce understand since he was addressing that message to Bruce.

Old Henry!

Very, very clear what you wrote, God bless your patience trying to explain all this.
Bruce will not be offended because his method is useful and precise too.

Now I will get a timing light and I will see the result.

I know you will understand, all my sacrifice and hard work concerning my car, There is a reason,I love my car!

I think that I have learned a lot here in Fordbarn, I really thank you so much!
i will back for more news!

[Bruce Lancaster]

Ron is talking about the need on all engines for a true vac advance or other method to advance spark under light load...Smokey Yunick* also talked about this! Ford used the Mallory system, not a true vac advance. For now issue is getting stock system just right before messing with things...as in do not mess with overall timing until the existing vac brake is working and adjusted.
Doing the degree divisions with paper and compass is a way to bypass the issue of measuring really odd dimensions onto a curved rim...no need to space off 4.73 millimeters while hanging over the radiator, just hold up a segment of your piece of cardboard and copy the marks from one curve to the other. The degrees on the cardboard can be made as accurately as you care by extending the lines, but actual final accuracy is going to depend more on the final marking of the pulley, which is going to be a bit crude in most cases. No need to match protrator size...you just draw all lines from center all the way across the sheet, then cut out the center to match pulley. Where the lines cross the cut they are at right point for that circle, and you can cut the outside however you need to in order to place it against the pulley rim.
Once you get to proper stock settings...time to hit the road and experiment! Each car has its own preferences.
These things were road-raced hard in Argentina; I bet there are some elderly racers down there who know a trick or two.


*Yunick opined that the lack of vac advance was responsible for race engines fouling up during pit stops and slow laps, and also for the continual need for new sparkplugs in racers. Their advance systems were correct only at full throttle and were incapable of proper combustion and power at anything less.

[Harylufa]

Hi!
One question I attach a pict of my dist, I has 7 little line, Is this marks degree?
Dist has already been tested with its 22º and a half in both points as the manual say. The advance (screw) is in the middle.
From my ignorance, if this little line are degree as it is u¡in the middle this would be 0. And I must advance 4º clockwise, I hope be clear.

Thank you!

[Bruce Lancaster]

Correct place for the line is where it ends up after the ruler test shown above. If everything is perfect after 65 years of repairs and wear and changed parts, when you time it that way it will then test at 4 degrees running with your new marks and a timing light...
If it does not correspond precisely, the two methods compared will tell you where 4 really is by your presumably correct new timing marks.
Correct spot is normally very close to center, leaving the slot for use in fine tuning.
The ruler method is a Ford developed expedient method to get timing to specification for those without access to a distributor machine or timing fixture.
Also the Ford method allows you to do all distributor work in comfort in your shop except for the quick removal and replacement, and also to keep a spare distributor that can be bolted on and run without further work.

On the ruler method...note that you could easily build a simple fixture onto a ruler that would insert into the bolt hole and hold the ruler the correct distance out, making the job physically simpler.

[Old Henry]

Originally Posted by Harylufa

From my ignorance, if this little line are degree as it is u¡in the middle this would be 0. And I must advance 4º clockwise, I hope be clear.

Those little lines are about 2 degrees each. The point that yours is set in your picture is right at 4 degrees BTDC. Moving it down (clockwise) will advance even more than the 4 BTDC. Moving it up (counterclockwise) will retard it.

[Straightpipes]

Smokey Yunick must have sold his soul to the devil to know what he knew......Good thing he passed some of it on.......

[Old Henry]

For those of us that never heard of Smokey Yunick, we can read about him here: http://en.wikipedia.org/wiki/Smokey_Yunick