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07-25-2018, 07:08 PM | #1 |
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Centering a Model A Crank, in a Block !
Many a Model A cranks are set off center to the front, and Rear Main, ( Which is most important ) to keep a rear main from leaking, and also time gear mesh in front.
If the crank is off center, as much .010 thousandths, it will cause a leak, you can not fix, with out pouring the Babbitt again, and Align Bore again, this time centering between the Main bolt holes. On the Model A , Ford used the Left hand rear Main Bolt , on the Drivers side of the car, and gaged ALL their machining Operations off that bolt hole. The big problem with that, all Align Bore Machines have a Jig, with a set center distance, ( So you get the Gear Mesh Right ) that is used at each end of the block, but while the center distance can be right on, the crank centering, is often not. An off center crank will leave a gap between the crank, and the Aluminum Seal, and you can't stop oil unless you close the gap. Even if everything else is right, you have a leaker. The Factory cranks were always centered, but very few new Babbitt jobs I have seen are. I have all the jigs sets with my TA-15, A,B,V-8, and Fordson, and none I can use except the V-8, and that I have to use 1 to .005 thousandths of shims, depending on the motor to get the right center distance, but they will center the crank on the V-8"s. Herm. |
07-25-2018, 08:19 PM | #2 |
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Re: Centering a Model A Crank, in a Block !
Nice job!
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07-25-2018, 08:56 PM | #3 |
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Re: Centering a Model A Crank, in a Block !
The left hand rear main bolt hole that Herm mentioned was reamed to .505 inch diameter to a depth of 1/2 inch.
From the center of the above hole to the surface of the rear main thrust bearing is specified to be 1.4335/1.4345 inches. These dimensions are from the Ford drawing of the cylinder block. |
07-27-2018, 02:12 PM | #4 |
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Re: Centering a Model A Crank, in a Block !
Herm, My Kwik Way and Ammco align boring machines pick up off the block main bearing holes, but leave no compensation to acquire the cam centerline to crankshaft centerline distance. I see you like the Tobin Arp set up. Rather than setting up off of false camshaft centerline what would you recommend. The KR Wilson uses a false camshaft bar for the combination machine how do they guarantee proper center to center distance of boring bar frame?
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07-27-2018, 05:56 PM | #5 |
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Re: Centering a Model A Crank, in a Block !
Along with my normal Kwik Way alignment jigs I came up with this set of jigs to make sure the cam to crank is correct. Only have found one block out of many that the Kwik Way jigs were off but no more than a few thou.
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07-27-2018, 08:52 PM | #6 |
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Re: Centering a Model A Crank, in a Block !
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07-27-2018, 09:56 PM | #7 |
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Re: Centering a Model A Crank, in a Block !
Mr. KR, I used a N.O.S. Kwik-Way for about 5 years when I was a Kid. There are many things I can do on a Tobin-Arp, I couldn't do on a Kwik-Way, but the Kwik-Way is the best Align Bore out there if you are doing only Motors. You also have to make sure that the bar is not wore, and the two center springs, and Collar are set to, I think, been a long time, to 1/2 inch compression, for Bar sag.
OK, John, that is what I was talking about, when a set distance jig is used, you are Limited on getting the crank on the center line, and centered in the block. So if you are off by .010 thousandths, which is very easy, your front seal, rear seal, rear shims, and the transmission Pilot shaft, and Pilot bearing will be off. So, Guys, what I did, on the Kwik-Way, was to center the Boring Bar first, and lock the bar bearings, so it stayed. I have a used Kwik-Way bar, and two Kwik-Way tapered cones, and run it through the cam holes. Then what ever Center distance you use, take that and add half the diameter of each bar to your center distance, and then Mic around each bar and get a feel so the Mic just passes with very light drag. So, now, with the bar centered, the only direction for adjustment, is up, and down. Now for that adjustment, you use brass shims to go under your Alignment caps, always equal, on both sides of the two Jigs. I have always had to go up, never down. Another way to center the bar, is make 4 plugs, two for front, and two for the rear. I will try to find some pictures to show what I am talking about. These plugs just fit the holes in the mains with no binding, or looseness. I made mine for T, A, and B's, all in the same plug. Herm. |
07-28-2018, 02:22 AM | #8 |
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Re: Centering a Model A Crank, in a Block !
Hi Herm,
Thanks for passing on your experience. I have a Kwik-Way and it has been real good to me. I don't pour my own babbitt I have a few poured at a time and cut them as I need them. I always like to see how others are doing things. You pick up something each time. Keep posting....... Dodge |
07-28-2018, 09:07 AM | #9 |
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Re: Centering a Model A Crank, in a Block !
Beautiful!
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07-28-2018, 09:22 AM | #10 |
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Re: Centering a Model A Crank, in a Block !
This helps us understand, WHY some engines don't FARE well & WHY some are constant OIL LEAKERS!
Bill W.
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07-28-2018, 12:11 PM | #11 |
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Re: Centering a Model A Crank, in a Block !
I just realized on the drawing of the plugs, that I don't have the length of the bolt stub shaft, and the " B " dimensions. But these are for a 1/8th inch bar, and Kwik-Way is 1.250, anyway, but you get the idea.
Herm. |
07-28-2018, 12:25 PM | #12 |
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Re: Centering a Model A Crank, in a Block !
Everyone is BRILLIANT, in one way or another!
Bill W.
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07-28-2018, 01:58 PM | #13 |
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Re: Centering a Model A Crank, in a Block !
I’m pretty much doing the same as Herm is on my TA-14 except I have converted my machine to use a 1.000” boring bar so I can do Model-Ts too. I locate very similar to Herm’s method with the pins except I have different ones for T's, A's, & B's. Also, I set up a little differently in that I have a modified crank gear for both an A & T that has been bushed down to just slide over my boring bar. I install the camshaft & timing gear I plan to use during the rebuild, and then move the vertical height of the block to be able to set the desired backlash. Next I have a bridge that I made with an indicator mounted into the center that I place over the boring bar at the front main after my lash has been set. I use that bridge with an indicator to measure the set height of the bar, and then use that measurement to set my bar height over the rear main. This ensures the bar is parallel with the block, and as Herm mentioned, the pins locate it side to side.
One other thing I like with the Tobin Arp units (-over the K/W LBM) is their hydraulic drive unit which pushes the bar very smoothly with infinite speed control. Nothing wrong with either set-up, and I know of a gentleman down in Alabama that uses a KR Wilson Boring Plate that he mounts on T blocks and drives the boring bar unit with a T/A drive unit, and it produces some very pretty bearings. I kinda think he may have bored his boring plate from the 15/16" to 1.000" too. . . |
07-29-2018, 02:18 AM | #14 |
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Re: Centering a Model A Crank, in a Block !
Brent, your crank gear idea is brilliant I’m going to make one up also.
Thanks for sharing. |
07-29-2018, 11:31 PM | #15 |
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Re: Centering a Model A Crank, in a Block !
Herm the brass shims makes perfect sense to attain the correct camshaft to crank center to center dimension. I notice you use the Kwik Way kwik clamp bolts. I see you use a Storm Vulcan rod groover also. What depth is usually desired for the tool bit to enter the babbitt? Do you also chamfer the rod oil holes?
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08-01-2018, 06:51 AM | #16 |
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Re: Centering a Model A Crank, in a Block !
So..my question here is in order for this to work properly the crank would need to have been ground properly....
Herm was saying that if a Model A crankshaft is ground off center it would throw off timing gear mesh and crank centering or would this method compensate for that? Steve |
08-01-2018, 07:10 AM | #17 | |
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Re: Centering a Model A Crank, in a Block !
Quote:
As far as grinding off-center, I have a Storm Vulcan 15 grinder that uses centers. I indicate one end off of the surface under the crank gear, and the other off of the rear flange. If the crank is straight, it is difficult to be off if both ends are running true. A crank press is used to straighten one if it is out. |
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08-01-2018, 07:42 AM | #18 |
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Re: Centering a Model A Crank, in a Block !
Brent, What/why would cause a crank be set off center? Herm had mentioned in another post that some shops do not know how to properly grind a Model A crankshaft. This could potentially put the crank off center leading to oil leaks and cam gear mesh issues?
Steve |
08-01-2018, 11:03 AM | #19 |
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Re: Centering a Model A Crank, in a Block !
Two separate Machine operations.
1. Grind the crank to the center line, of the crank. 2. Align Bore the block to the center line, side ways, and up and down. 1. Dead center between the bolt holes, side ways. 2. Up and down with the correct center distance, on both front, and rear main. Herm. |
08-01-2018, 11:43 AM | #20 |
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Re: Centering a Model A Crank, in a Block !
Pictures, I also have the Hydro-Borer for sale, it was Factory rebuilt in about 1950, and never used, long story!
\Herm |
08-01-2018, 12:54 PM | #21 |
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Re: Centering a Model A Crank, in a Block !
Herm,
I have Kwikway fiktures like these; http://www.fordgarage.com/pages/kwboringbarfixtures.htm Will they center a bar in the correct location? Steve |
08-01-2018, 04:03 PM | #22 | |
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Re: Centering a Model A Crank, in a Block !
Good question. I would think the most logical response would be 'machine operator error' however with that said, Ford's approved method back in the day was with the KR Wilson machine that used a boring plate that aligned against a bar that was inserted into the cam bores. Depending on the pressure placed against the false cam, in my mind it is feasible to see a few thou. variance each way off of centerline. The KRW set-up is not the most rigid set-up nor is the portable Kwik-Way unit however those units produced very nice engine bearings that went many miles, so maybe accuracy (-while desired) is not all that crucial. Some food for thought in that while it is desirable to have the crankshaft in perfect alignment with the center-line of the cylinder case (block) however if a crankshaft is off by a few thou., does it not seem plausible that this was/is corrected when the flywheel housing was/is aligned and shimmed? By doing this, it allows the transmission and its' input shaft to be parallel in alignment with the crankshaft. Quote:
Steve allow me to add to what Herm said above. In my opinion, ummmmm, Yes, - and No about putting the crank off-center. I will preface this by saying that I have only ground crankshafts on one type of machine, and I am sure Herm has way more experience with grinding cranks on multiple machines than what I do, ….however theoretically, the grind of the crankshaft would have nothing to do with the Cam gear to Crank gear backlash UNLESS the operator did not index or indicate the crankshaft into the chucks correctly. In this scenario, the front main journal would be ground non-concentric and the lash measurement would vary during rotation of the crankshaft. So he is correct in that regard and I will yield to his expertise over mine. So that everyone else understands the process of crankshaft restoration/rebuilding/refurbishing, the crankshaft is usually soaked in a tank to rid the oils & grease followed by a hot jet wash. Some shops use an oven to bake the crankshaft to turn the oil into an ash in lieu of soaking. From the wash cabinet, I leave the crank gear on the snout and run it thru a rotoblast cabinet with shot about the size of pepper to clean it. Then the crank is crack-check with an electromagnetic machine. If it passes the crack check, I set the crank on a pair of Vee blocks and use an indicator on the center main to check for run-out. If there is run-out, it generally means the crankshaft is bent, and at that time it is straightened in a press. Once that is complete, the crankshaft is installed in the grinder. Mine uses centers to hold it. I use an indicator that measures in tenths that I indicate from the surface under the crank gear and on the rear flange. Once I have both ends running true, I have a Last Word indicator that I check the face of the flywheel mating flange with for run-out. Where I believe the difficulty probably lies for many grinders is in the wheel. Ford specified an 1/8th radius on the cheeks of each journal pin. Since the majority of the cranks I do are Model-A, grinding my stone wheels to match this radius is not that big of a deal however for grinders that do multiple styles of cranks, they do not like the waste of material that comes with dressing their stone in this manner for Model-A cranks. The other issue that is difficult is that my grinder (-as is most others) are plunge grinders meaning we do not grind the journal in a lateral motion (like a typical metal lathe with a traversing carriage) but we come into the journal in a perpendicular motion and grind away material. Since my wheel is just over 1.250" wide, I must make 2 plunge cuts completing the first operation and then move out and over to the other side of the journal and repeat the process. Where this gets tricky is the tolerance across the entire 1.625 rod journal or 2.175 main journal width is 2½ ten thousandths of an inch! Not saying this is the right way, but the facts are that crankshaft grinding is about the least profitable operation in the shop, and there are likely shops that look for ways to trim the time necessary to do the job correctly as a way to cut costs. Herm, that is a cool babbitt boring machine. It should be a great asset to someone wanting to pour their own rods inhouse. I have a Storm Vulcan #24 Rod Machine that uses a boring bar spun between centers that has 3 cutters on it plus the chamfering cutters on both ends. After set-up and after the poured rod is placed onto the mandrel, it actually cuts a poured rod to finished size in about 55 seconds from end to end. From there I cut the X grooves with the same cutter as you have. |
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08-01-2018, 07:32 PM | #23 | |
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Re: Centering a Model A Crank, in a Block !
Quote:
Mine didn't on some, you will just have to check yours ? Herm. |
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08-01-2018, 08:47 PM | #24 |
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Re: Centering a Model A Crank, in a Block !
so maybe accuracy (-while desired) is not all that crucial. ' END QUOTE "
Then the job should also be 1/2 price ! Some food for thought in that while it is desirable to have the crankshaft in perfect alignment with the center-line of the cylinder case (block) however if a crankshaft is off by a few thou., does it not seem plausible that this was/is corrected when the flywheel housing was/is aligned and shimmed? By doing this, it allows the transmission and its' input shaft to be parallel in alignment with the crankshaft. " END QUOTE " The only way you can grind a crank straight, is indicate off the time gear area, and O.D. of the flange. The gear should be pulled any way, as they will never match a new cam gear. Also when the mains are ground, then the rear flange should be trued, before the center is lost, or you can have some extra flywheel sticking off one side of the crank. That doesn't do much for Balance. There is absolutely no way in this world that you can shim a flywheel housing to redirect the pilot shaft to a pilot bearing, where the crank is not centered. All that will happen is the Pilot will be on a bind all the time. The only reason you shim the flywheel housing is to get the transmission bell at a right angle to the crank. You can't do that if the crank is not on center for any reason, and it sure doesn't do the rear main Babbitt any good, as it would be doomed from the start. After set-up and after the poured rod is placed onto the mandrel, it actually cuts a poured rod to finished size in about 55 seconds from end to end. From there I cut the X grooves with the same cutter as you have. " END QUOTE " All Grooves of any kind should be cut Before the finish cut. I have a Vulcan machine, same as a Storm, as Storm bought them out, and made the same machine, only they put free standing belt shields on the ends. I sold a National, and an AMCO. Herm. |
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