Who Checks for Rod Alignment?

[edmondclinton]

Herm Kohnke in a post in another thread stated that almost nobody, meaning Model A engine rebuilders, checks for connecting rod alignment., i.e., bent, twisted or off-set. I find this almost unbelievable with the prices they charge for a rebuild nowadays.

He also said, "I know J & M machine always check alignment, and Vern the builder in Fort Dodge, Iowa, at Aronald Motors, has a sunnen Aligner, and the rods that won't fit his machine that are too small, he sends to me."

I think it is very important that we Model Aers should know which ones perform this vital step and which ones do not. Below is a list of the most common builders often mentioned on this site. Who checks for rod alignment of the following; yes or no:


1. Rich @ AER in Skokie

2. H&H

3. James Rogers

4. Schwalms

5. Snyder

6. B. Terry

7. Joe Silva

8. Bert's

9. John Cosper in NM.

10. Ron Kelley

 

[tbirdtbird]

interesting thread. You ARE supposed to check for this

John Cosper does not do internet stuff FYI; his wife used to do this for him; so you won't get that answer here; ask when you call

 

[edmondclinton]

interesting thread. You ARE supposed to check for this

John Cosper does not do internet stuff FYI; his wife used to do this for him; so you won't get that answer here; ask when you call

Thanks for your response tbird. Members of this site appear to discuss nearly everything when it comes to vendors and service providers and many of them use this site to promote their sales and services. I see no point in calling all these engine builders. If they see this thread they can reply themselves. If not, then this thread will serve as a reminder for Model Aers to inquire when trying to decide which one to use. Thanks.

 

[Joe K]

But if your machining/boring setup is correct, a rebabbit/rod bore is as good as it will ever get?

I've not done this (don't rebuild engines for a livelihood) but have done enough machining to appreciate the fact that setup is probably done from the bush (small) end as reference.

Check (and rod bending) is for possible accidents to an engine - and evaluating/correcting parts for re-use without rework.

Or maybe bending a rod before the pouring mandrels are ever put to it?

Mr. Kohnke cue?

Thanks,
Joe K

 

[BRENT in 10-uh-C]

herm kohnke in a post in another thread stated that almost nobody, meaning model a engine rebuilders, checks for connecting rod alignment., i.e., bent, twisted or off-set. I find this almost unbelievable with the prices they charge for a rebuild nowadays.

He also said, "i know j & m machine always check alignment, and vern the builder in fort dodge, iowa, at aronald motors, has a sunnen aligner, and the rods that won't fit his machine that are too small, he sends to me."

i think it is very important that we model aers should know which ones perform this vital step and which ones do not. Below is a list of the most common builders often mentioned on this site. Who checks for rod alignment of the following; yes or no:


1. Rich @ aer in skokie

2. H&h

3. James rogers

4. Schwalms

5. Snyder

6. B. Terry

7. Joe silva

8. Bert's

9. John cosper in nm.

10. Ron kelley

yes

 

[jetmek]

I don't believe that Mr Kohnke can rightfully comment as to what almost all other rebuilders do or don't do. Any machinist worth doing business with knows that aligning and weight matching rods are not optional.

 

[edmondclinton]

I don't believe that Mr Kohnke can rightfully comment as to what almost all other rebuilders do or don't do. Any machinist worth doing business with knows that aligning and weight matching rods are not optional.

I can't speak for Mr. Kohnke directly, but I think he bases his statements on the rods from the engines that have come into his shop for the last 48 years plus ones purchased.

"Any machinist worth doing business with knows that aligning and weight matching rods are not optional."

Very true. But you'd be surprised as to what actually goes on sometime and how some engine builders look at it. For example, I like rods balanced end for end. Some of these Model A engine builders don't know what that means.

 

[Kohnke Rebabbitting]

Mr. Jetmek, I have been rebuilding Rod and mains for 48 years now, and it has not been an after school business.

I had 5 employes, and for many years we worked 7 days a week.

We have built countless engines, and hundreds of thousands of all kinds of rods and mains bearings.

Mr. 1930 Coupe stated it very well, they are always off, and while only a few thousands, they are not good enough to put in and engine.

I will say again, there is no rod lathe, or boring machine that will machine them straight, that is why "THEY MAKE ROD ALIGNERS"!!!!

Mr, Jetmek, I can safely say that most rod builders do not check there rods for Alignment, and if they do, it's a P poor stab at it as I have checked all kinds of rods from other companys. Many Guys put there own engines together, and like many rod builders don't even have a rod Aligner, so many are sent in here.

When asked if they check Alignment, the answer normally is, our Rod lathe cuts them straight, and that is a statement lacking of knowlage.

Mr. Ed., the question you ask, may have and expected responce.

About bent rods that you can see a bow, or say a bend. There are rods that look bent after straighting.
To fix rods like that, you have to straighten the web part of the rod, the offset, the twist, and a bend, but you can't use the same proceeder as if it had babbitt in it as most babbitt areas are not machined and you could make the Alignment worse.

So if you have to bend the top part over a long way for the off set, you have to bend it right under the wrist pin. Other wise the the further you get away from the wrist pin, the more of a bend you will have when the rod is straight.

Herm.

 

[Kohnke Rebabbitting]

Here are some pictures of a 1929 Chevy that came in yesterday from Ne., that had less then a 1000 miles on it. I have the engines shipped to Vern, at the Arnold Motor Co. in Fort Dodge, Iowa. They tear down the engines, clean them, and do the machine work, and I might add, there work is perfect. I do the bearings, and they assemble again, IF the owner wants, or they just ship out the fresh machined parts.

While I have a better insight because I was there, I have tried to take pictures of some of what was wrong.

Look the pictures over, and comment on what you can see that is not good.

Herm

 

[d.j. moordigian]

Well,...if you have a Sunnen Rod checker, you can do Model A rods.
You need the "TN-120 Midget Attachment"...

BTW,...you always check the rods.

 

[edmondclinton]

Here are some pictures of a 1929 Chevy that came in yesterday from Ne., that had less then a 1000 miles on it. I have the engines shipped to Vern, at the Arnold Motor Co. in Fort Dodge, Iowa. They tear down the engines, clean them, and do the machine work, and I might add, there work is perfect. I do the bearings, and they assemble again, IF the owner wants, or they just ship out the fresh machined parts.

While I have a better insight because I was there, I have tried to take pictures of some of what was wrong.

Look the pictures over, and comment on what you can see that is not good.

Herm

Unless it's just the picture, it looks the rods are visibly bent. The sides are chewed up with a bunch of cuts and nicks too. Also, the rods are not in the middle of the piston, sort of cocked over to one side.

The cotter keys appear to be missing.

The main bearing bolts did not have the lockwasher retainer tabs bent down over the bolt heads.

The cylinder head was either out of flat when installed or got too hot and warped or in other words is low in the middle allowing combustion gases to flow across between the cylinders thus the blackened and burnt head gasket areas between the chambers and the blackened areas on the head's gasket surface area.

 

[Kohnke Rebabbitting]

Unless it's just the picture, it looks the rods are visibly bent. The sides are chewed up with a bunch of cuts and nicks too. Also, the rods are not in the middle of the piston, sort of cocked over to one side.

The cotter keys appear to be missing.

The main bearing bolts did not have the lockwasher retainer tabs bent down over the bolt heads.

The cylinder head was either out of flat when installed or got too hot and warped or in other words is low in the middle allowing combustion gases to flow across between the cylinders thus the blackened and burnt head gasket areas between the chambers and the blackened areas on the head's gasket surface area.

very good Ed., the keys were taken out by Vern, and also the locks, but you seen them.!

Yes, the head was leaking in 3 places between cylinders, and the head gasket had not the slightest of gasket cement on it.

The rods were new, and are of lead babbitt, and are out of alignment, as when you turn the motor over, the wrist pins and pistons move around in the cylinders, the way they should not.

The rods are smooth in the I.D., as they should have had X Grooves, and the center of the cap should have an oil well cut in the center of the cap, clear to the steel of the cap.

The mains have the original bearings in and, the thrust was wore off to allow the crank to move forward so the ends of the rods hit the wrist pin bosses, and the front main bearing was thrusting off the inside of the front bearing shell.

This engine was supposed to have new babbitt mains, and rods, the owner is not happy, to say the least.

The rods were also put in backwards, as the wrist pin bolt should go towards the cam shaft, reason being the dipper hole in the caps are drilled off center, so when the dipper is put on the oil hole in the rod cap sets at the far end of the dipper.

Thanks Ed.,

You know your stuff.

Herm.

 

[Archie Cheda]

I agree whole-heartedly about the importance of rod alignment and am grateful for the posters in this thread who reminded me not to put off this check.

Let me try to add to the discussion: I agree that anyone who does work on the big or small ends of any rod is not completing the job without checking alignment -- I have depended on my professional automotive machinists for this many times over the years and have never been let down. In my retirement I have the time (and the equipment) to do this myself -- just for the fun of it. The two Model A engines I have taken apart in the past few months both showed signs of being cured of being "stuck" by means of a tow rope . . . their cylinder walls suffered from this treatment, but I found the rods to be out of alignment, probably from the same treatment. Remember the rod applies the force to free a stuck piston.

Pardon me for becoming a crusader on this subject, but it seems to be somewhat neglected in discussions on this forum. Of course, it is silly to think that if the "stuck" engine can be freed up that no harm has been done to it. I have been there and share the emotion -- one hopes that everything will be fine . . . My two engines both suffered damage -- one too severe to cure by anything less than a re-bore, but the other is within the range of a hone job. The rods on both engines are not in good alignment and I would like to suggest that the process of using force to unstick an engine is inherently a bad practice. Not only does the force result in ripping pieces off the rings and cylinder walls, but when the forces are not symmetrical (this likely being the typical case), great forces are placed on the pistons and rods, resulting in rods that are not in alignment and perhaps collapsed piston skirts.

It seems to me that there are two things that everyone should think about:

Before storage, place a table-spoon of oil in each cylinder and turn the engine over two turns to spread the oil around. Every year turn the engine over at least two turns. Do NOT start the engine unless you are willing to run it until is is thoroughly warmed up. If an engine is only run a short time, there is major condensation in the cylinders, resulting in rusting the rings to the cylinder walls.

Once an engine is stuck (by a previous owner?), do not be in a hurry -- use your favorite concoction to soak the rings and break down the hold that corrosion has on them. During this time (days, perhaps weeks) only apply low levels of force and in both directions to help the fluid work its way into the corrosion. My choice is Kroil, but many folks use 50-50 acetone and ATF. (I would too, but I already have a gallon of Kroil.) I used Kroil after spending weeks using other fluids on a hit & miss engine -- I was applying force with a 12# sledge on a 4x4 against the piston head and nothing worked until the Kroil. After a two-hour soak with Kroil, the piston came right out with minimum force. (Your mileage may vary . . .)

Archie

P.S.: Let me ask those who have strong opinions:

Say I check a rod to make certain that it only has minor alignment issues and am certain that it is straight within my ability to visually inspect it and then hold it securely by its beam on the table of my vertical mill. If I then bore both the babbitt and a newly-installed and burnished wrist pin bushing without disturbing the set-up between the two operations, should I not expect to get good parallelism and no twist? (I add that I would still check alignment, but I would not expect to make any corrections.)

 

[ursus]

Years ago and under a different shade tree I helped a friend replace a bad rod with a slightly used rod of the correct size. The result was that we eliminated a rod knock and installed a piston slap. An old guy told us we had a bent rod and explained how it could be checked on an alignment device. The problem was that we had no such tooling around so he showed us how to check for a bent rod by dropping the piston (minus rings) and rod assembly back in the engine and checking for clearance throughout the stroke cycle with long feeler guages in place. Sure enough, we found the kink and, after several iterations of removal, bending, and replacement, we managed to eliminate the slap.

I wonder if anybody else has heard of or done this?

 

[Kohnke Rebabbitting]

Archie, it would be the same problem, no matter what kind of of machine you used to machine a rod, as there are to many variables.

Even when a mill, or our rod lathes, and even a modern rod boring machine is used, they are not zero.

I am not including a wore out machine in this, but the problem is, that a rod has to be clamped some how in any machine, and I don't care how you do it, the metal moves, and that is what you have to correct.

I am not saying you can't get lucky, but the odds are against you.

I agree with everything you said on stuck pistons Archie. Sliding the rear wheels on a Model A, and C-4 should never happen.

Thanks,

Herm.

 

[ursus]

I should add that I greatly enjoyed the look back in time provided by Mr. Kohnke's pics of the '29 Chev "Stovebolt Six" engine. Like the Model A, those things sure had their own unique kinds of problems that could crop up. The sturdy center main still allowed for a some crankshaft whip, what with 6 cylinders on a 3-main crank. You could wind them up to 70-75 MPH, but definitely at your peril. Ahh, the stink of wet horsehair in the cushions ...

 

[Archie Cheda]

ursus,

I have not used the method you describe, but it should be something every student-mechanic does as some point so that they understand what a crooked rod puts the piston through. If I were teaching auto shop, I would set up a dummy engine so that this lesson could be learned in minutes.

Herm,

I have been thinking about my own question since I made my post and embrace your answer completely. The following is based on my experience teaching tool design for many years:

Part I: If one could grind the sides of the beam parallel in a grinder, one could then hold the rod without introducing any change in shape that would come out when the rod was unclamped.

Part II: If one supported the rod on two points on the beam edges near the big end and one in the center of the web near the small end, it would be supported on three points and would be stable. If it were clamped opposite these three points, there would be no change in shape caused by the clamping process. This sort of clamping would easily keep the rod in a fixed position during the machining and, upon release, I would expect no change in shape.

It seems that Ford tool designers beat me to this description by close to a century. The old-style rods with three center holes in bosses on the forging are an elegant version of three-point support of a part being machined. I would expect that later rods that did not have these bosses used tooling similar to what I am describing.

And, I still would check (& straighten if necessary) every rod . . .

Thanks,

Archie

 

[edmondclinton]

Once an engine is stuck (by a previous owner?), do not be in a hurry -- use your favorite concoction to soak the rings and break down the hold that corrosion has on them. During this time (days, perhaps weeks) only apply low levels of force and in both directions to help the fluid work its way into the corrosion. My choice is Kroil, but many folks use 50-50 acetone and ATF. (I would too, but I already have a gallon of Kroil.) I used Kroil after spending weeks using other fluids on a hit & miss engine -- I was applying force with a 12# sledge on a 4x4 against the piston head and nothing worked until the Kroil. After a two-hour soak with Kroil, the piston came right out with minimum force. (Your mileage may vary . . .)

Archie

You and others may think it's baloney but I have found that the best thing to free up stuck pistons is used motor oil. You heard right, dirty oil.

Pour it down the spark plug hole and let her soak. The used motor oil contains a mild acid. Won't hurt a thing.

Of course you might want to remove the pan before pouring it in so you can clean things up if any gets past the rings.

 

[Archie Cheda]

I certainly would agree that any mild acid would help break down rust. Some folks use soda pop which is acidic (ask your Dentist). The patience to let it soak and work is another factor. When soaking parts that are accessible, some mild tapping sets up vibrations that allow the penetrant to move deeper.

Archie

 

[tbirdtbird]

lots of fav soaking solutions out there for sure.

I use MMO and every day I tap on a wood block on top of the piston with a 3 lb sledge. Every day. One day the piston will move slightly. It is all but over then.

For readers new to this stuff, what do you do if the stuck piston is at the top of its stroke? No space for any soaker fluid of choice!!

Use modeling clay (NOT Play Doh) to build a dam around the top of the bore, then dump in your juice.