My 12v alternator case blew up on me today on my way home from a show. Looks like the screws holding the case to the adaptor plate loosened up. Let's just say, thank goodness for AAA.
Anyway. I am taking some thinks apart to make sure that nothing else broke. For what happened, it sure seemed worse by the way it felt. So far I know I do not have a broken crank or any broken valves. It just didn't feel right when trying to turn it back over after it quit.
In the process of tearing down, my distributor fell off, since one of the alternator/generator bolts is what holds it in place. So, I have to reinstall it and get the timing right.
I have enough experience with installing distributors in newer car builds. So I know that at #1TDC the rotor should be pointing at the #1 plug wire for 0 degree timing.
My question is, when the T's and the manual advance, what position is fully retarded? Is it 0 degrees when the lever is all the way up? Or should it be after or before?
Can anyone who has more experience with T distributors lend a hand with installation tips?
It should be a few degrees after TDC. What is important is where the points break (open) and not the exact pointing of the rotor, though the rotor obviously needs to point near the #1 plug wire terminal when #1 is just past TDC and barely in its expansion (power) stroke.
Since a T can break your arm if you try to hand crank it with the timing advanced at all - the factory setup with coils has the timing set at about 15 degrees retarded with the timing lever all the way up (full retard position) and starting on battery. I don't know how much range then of advance you have with your linkage since that varies somewhat with each distributor linkage setup but if you have enough advance such that it runs OK - that would probably be a place to set the initial timing.
Oops - I guess I was typing the same time Seth was.
No problem John! Brian gets the same message twice now, so he should be good and safe.
Seth, you said that what is important is where the points start to break open. What if your distributor has a Pertronics pointless conversion in it?
Good point Terry.
Many folks throw out the Petronics and other fine electronic conversions and go back to points and get better better running engine.
That is ususally because they did not get the thing so it sparks when the rotor is right at the distibutor cap contact.
If it is off too much the spark will jump to the next closer contact even though it is farther away because under compression it is harder for the spark to jump the gap than jump to a cylinder's contact that is not under pressure.
With points where the screws holes are located dictates where the points will break.
I have hole-sawed the distributor cap and run the engine so I could look in there and see where the rotor was when the spark occured. Of course that cap with the hole can't stay on the engine once you get everything set.
Here is a procedure that will work fine to set the timing with a Pertronic distributor.
Move the spark rod all the way up. Remove #1 spark plug and slowly crank the engine over until #1 piston comes up with both valves closed, then continues until the piston drops down 1/8th inch. Reinstall the distributor with the rotor pointing toward #1 spark wire. Remove the #1 spark plug, leave the wire connected and ground the case so it will spark when its turn comes. Loosen the distributor collar that is connected to the spark rod.
With Petronics, you still remove the #1 spark plug, leave the wire connected and ground the case so it will spark when its turn comes and set the piston just past top dead center (down about 1/8th inch). Turn on the ingnition and rotate the distributor case in the opposite direction that the rotor turns, until the spark occurs. Then tighten the distributor collar.
To test the setting, slowly crank the engine over a complete turn for #4 to fire and another complete turn for #1 to fire again. Note the piston position at that instance. If it is down about 1/8th inch you are right on and done.
This sytem always worked fine for my MGs and Morris Minors years ago.
So from what I can gather the rotor should not be right at #1 when I am at #1 TDC? It should be at #1 wire when the #1 piston comes down a bit from TDC?
John Montioned factory (fully retarded) timing set at 15 degrees. I can measure out 15 degrees on my crank pulley and figure it out that way.
So I will make that point (15 degrees past TDC) be my fully retarded position and will re-adjust the rods accordingly. Then the range of movement in the spark lever should take care of the rest.
Does anyone know what the point gap should be on these T distributors? That way I can check that too once everything is back together.
Brian, that would be a great help to know how much 15 degres drops the piston from Top Dead Center. A good math major could work that out, but I never tried. I grew up on a dairy farm and go with the old farmer repairs most of the time.
My T starts best and with no choke action, when pulling the spark rod down 4 notches. That might be because 1/8th inch is too much, but less is difficult to measure or estimate and more is better than less for safety considerations and any slack in worn spark rods.
If the car is a brass car or black low radiator car then you can look under the bottom of the radiator and into the crankshaft pulley on the front of the motor. Everytime the pin in the crank pulley is exactly horizontal a piston is exactly at top dead center. That hole in the front of the crank for the crankshaft/pulley pin was the index hole for grinding the crankshaft in the first place at the factory. Just get everything hooked up and pull the plugs. Lay the spark plug wires out so that they can easily jump from spark plug end to ground with any spark. Turn on ignition and slowly pull up the hand crank. Stop when you hear one of the spark plug wires "snap". It doesn't matter which one so long as you know your timing is "close" and not on the exhaust stroke (180 degrees off). Assuming you stopped at the "snap" next pull the hand crank out and look at the pin. If the pin is exactly horizontal (9 o'clock - 3 o'clock) position then the cylinder is firing at TDC. If the pin is at 8-2 o'clock position then your timing is advanced. If at 10-4 then your timing is retarded but too far retarded. The correct setting is the pin sitting just a wee bit down on the right side in what would work out to be the 9:15 - 3:15 o'clock position. That would be about as perfect as it needs to be. So long as the pin is noticeably down on the right side and thus just past 3 o'clock then your timing is safe for hand cranking. This is about the most accurate way you can do it on a T.
If I remember correctly, half the diameter of that 3/8" pin through the crankshaft is very close to 15 degrees.
Well the timing is the least of my problems.
I found this morning that I have a broken crankshaft. It turned over just fine by hand, but that is just because it was a clean break and it still lined up when turning in a clockwise motion.
It snapped rightbefore the #2 piston.
I am looking at what cranks cost from Macs and Langs and they are at $1,200! Is that really waht they go for. Are there any cheaper sorces?
Find a T engine rebuilder near you and talk to them. They might have a source for used but grindable cranks. They are not super easy to find but way less money than the $1200 for one of the brand new high tech cranks. Most of us are using reground original cranks in our motors. Lang's is not that far from you. They are in Ashburnham MA and they might be able to help you find a decent crank and perhaps a good motor rebuilder in your area.
Tough break, Brian. Let's hope there's not too much collateral damage.
A brand new forged counter-balanced crank from SCAT is $1299 list and one drilled for oil pressure is $1499. Be sure to tell them the stroke you want and the journal sizes. www.scatcrankshafts.com will get you there in a hurry. Just drop it in and go.
All SCAT four cylinder flat head Ford forgings start as the same blank even if they are Model T, B or A cranks, they are all made from the same forging. Then they remove the unwanted material in order to make the desired crank. This results in a lower cost to the consumer and uniform material strength because of a good long run with the same alloy materials. SCAT makes over 9000 forged cranks every year. No I am not an employee nor do I own stock in the company, but I have been there and seen the operation in their 42,000 square foot plant and they do good work and sell a good product.
The picture below, from left to right. The types of cranks used in Model T Fords:
Model A, Chevrolet, Model T, Wills St Claire, and the next four are SCAT cranks; 1 is a rough forging, 2 is starting to make a Model T crank, 3 is a splash T crank selling for $1299 and 4 is a drilled for pressure crank selling for $1499.
Well in my opinion, apart from a cracked block, I don't know what could be worse collateral damage than a broken crank. Good thing is that everything else looks very good. I am most likely not going to dive into doing anything with it any time soon. Just let it sit and maybe look for parts when I can.
There is a good A and T restoration shop in my area that does engine rebuilds. I will check with them next time I can to see if he has anything.
Brian, the odds are not good that you will find a crankshaft the exact size that you need and that the bearings are not worn or the oil pan is not bent out of alignment to cause the break.
You basically will need a reebuilt short block, which is about $2500 on an average.
The reason the crank broke at a rod journal may be due to the main bearings not being perfectly aligned. This can happen when the center main is taken up to eliminate excessive clearance, or if the engine has been run a long time with a loose center main. Also if a journal is to break, one would think that number 4 journal should be most prone to failure because it sees the loads from all the other throws, however quite a number of the failures occur at the number 1 or 2 rod journal. The failures are nearly always from fatigue which shows up as a bunch of curved lines going across much of the break. With the center main out of alignment, all the throws are being flexed one way then the other for every crankshaft rotation which can produce fatigue failure. There doesn't need to be any load on the shaft to produce this flexing. That would make any journal be susceptible to failure which could explain why the number 1 or 2 rod journals fail.
There is some data to support this theory but it has not been absolutely proven yet. There is still much to be learned. I would be interested in knowing how well your mains are aligned if you can have them checked before installing a new shaft or replacing the bearings. Also you would not want to fit in a replacement shaft if the mains are not aligned.
Brian, the SCAT crank has to be an improvement over the original crank. If your bearings are in good shape the block could be align bored to fit the new crank. Your broken crank has either original size or under size main bearings so rebabbiting should not be required unless the babbit is damaged. One member of the forum manufactured a transmission main shaft assembly that likely solved any problems of misalignment of the fourth main. Perhaps you could use it. You don't need to be a professional mechanic to reassemble a T engine so you might consider doing the job yourself. The MTFCA distributes a lot of information on the Model T engine that would be very helpful.
In reply to Art's post... I am sure the crank broke due to my Alternator failing. When the car quit I got out and opened the hood and my alternator case was blown off and hanging by the wiring.
The screws that held the case to the adaptor plate must have loosened up and rattled the case off the bearing. The core tot eh alternator was still attached firmly to the engine and the bearing was still on the back shaft of the alternator. The case was cracked too.
My guess is that the case worked loose and then when it it fell off (since there is not a lot of room there to fall free) the spinning core caught on the case. Since the alternator is direct gear drive and tied in with the crank, this would have jarred the crank and caused it to break.
My crank did not break right at a journal. It broke before the #2 journal about an inch up as it goes to the #1 journal.
This is the only explanation that I have. I mean, the alternator case wouldn't have blown apart as a result of the crank failing. It must be the other way around.
Then too, if the crank alignment could change at all after breaking, the cam gears could have jambed and caused an instaneous stop of the camshaft and that sudden torque action applied to the alternator gear could have destroyed the alternator. All of which could have been caused by worn main bearings or a misaligned 4th main bearing.
Which came first, the egg or the chicken? That is a tough question to answer.
The alternator failure may have been "the straw that broke the camel's back" but I really think that the crank would have eventually failed.
When the crank was made many moons ago, it may have had discontinuities in the forging. Many crankshafts from model Ts show this. Stress concentrations occur around these folds and with many millions of fatigue cycles, become cracks.
I'm sorry that your crankshaft broke. But please remember that it was very old and you don't have any clue what all it has gone through in the past.
If you replace it with a vintage one, it would be a good idea to have it magnaflux tested at least, or better still X-rayed, because like yours that failed, it might be just about to do the same.
Brian, I have a pre-26 crank which I haven't had checked for cracks and it will definitely need derusting and then turning. I haven't miked it so I can't even give you jounrnal sizes. If you want it for FREE, all I ask is the shipping. I will mike it for you and you can decide. At the worst, you'll just be out the shipping and I won't have to make a trip to the junk yard.
Terry, thanks for the offer. If you are able to Mike it and let me know if it is grindable. When you get the chance.
I have a few other local people I could contact too. Let me know what you come up with through private E-mail message, that way I have it in my inbox for quick reference.
Welcome to the Two-Piece Crankshaft Club.
I believe one way to prevent re-paying your dues is to make sure your engine pan is straightened perfectly with a pan straightening jig before reassembly.
Good luck with the rebuild.
: ^ )
ps- If I was in your shoes, and could afford it, I would invest in the SCAT.
Well my local T mechanic said that a total rebuilt short block, using a reground original crank would cost $1,750. But if there are things in my motor that don't need replacing (ie: valves, lifters, pistons) then the cost could come down. And they get $2,650 for a full rebuld including trans. I figured I would ask, since you might as well do the trans while you are in there.
Getting the work done is not something that I am going to do right away, but at least I know what I am looking at from a reliable local builder. I find that to be very reasonable.
But it is a tough break on a car that I have been trying to sell.
If you have original Ford valves, replace them!
If you have cast iron pistons, I'd replace them.
If you have original solid tappets, I'd replace them with two-wrench adjustable.
While you are in there, I'd put in a Stipe cam or at least a Chaffin touring grind cam and bolt on a Z head.
Then you'll love to drive that 24 tudor so much you won't want to sell it!
: ^ )