Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 10-07-2019, 09:57 AM   #21
3739ford
Senior Member
 
3739ford's Avatar
 
Join Date: Feb 2017
Location: Dothan, AL
Posts: 325
Default Re: 8ba rod bearing problem

I still have the old bearings separated and marked where they went. If using plastigage what is the desired clearance on rod bearings. Just wanted to check and see how it would turn out. Perfect world would be getting them all the same and that is still option I'm considering. I want to change out front seal to one piece anyway since I'm back inside the engine.
3739ford is offline   Reply With Quote
Old 10-07-2019, 09:59 AM   #22
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,009
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by 3739ford View Post
JWL, the front and rear measure the same 2.106 and the two middle ones measure 2.115. I got to ask since I don't know what is the downside of running .030 on front and back and .020 on the middle ones.
Did you have the crank reground at the same machine shop? Even if they just polished it, should have measured/checked ALL the journals . . . so I'm still not letting them off the hook.
Bored&Stroked is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 10-07-2019, 10:43 AM   #23
40 Deluxe
Senior Member
 
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,774
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by Gene1949 View Post
find another machine shop. No REPUTABLE shop would grind a set of rod [journals] like that. God know what else they missed.
Wait a minute Gene. Apparently this crank was ground in the distant past when it was common to do this. Either by customer request or the crank guy wanted to save a little wear on his grinding wheels. The engine apparently ran a long time set up this way, so it was not a problem; nothing overlooked.
40 Deluxe is offline   Reply With Quote
Old 10-07-2019, 11:17 AM   #24
philipswanson
Senior Member
 
Join Date: Oct 2015
Location: Bonita, CA
Posts: 1,374
Default Re: 8ba rod bearing problem

Check it with Plastigage.
philipswanson is offline   Reply With Quote
Old 10-07-2019, 01:05 PM   #25
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,367
Default Re: 8ba rod bearing problem

Ford allowed more clearance on the connecting rod big end bearings than they did the mains. My old Mercury manual lists .0005" to .003" for rod big end bearing clearance and .001" to .0026" for main bearing clearances. Side play on the rods is .006" to .020" for two rods on one crank pin.
rotorwrench is offline   Reply With Quote
Old 10-07-2019, 05:10 PM   #26
cadillac512
Senior Member
 
cadillac512's Avatar
 
Join Date: Apr 2019
Location: Kansas
Posts: 897
Default Re: 8ba rod bearing problem

Sponsored Links (Register now to hide all advertisements)
I'd have no problem running dissimilar sized bearings if their crank journals are round,smooth,and correctly sized to their respective undersizes. And yes...it's time to get a micrometer and check-OR-if not possible, careful use of plastigauge on every journal of this crank after determining undersizes with the caliper. The machine shop personnel really should have checked and noted every journal-shame on them.


Terry
__________________
"It don't take but country smarts to solve the problem" (Smokey Yunick)


'41 Merc Town Sedan / 260" 8CM engine
'66 Fairlane four door / "warmed up" 302
cadillac512 is offline   Reply With Quote
Old 10-07-2019, 06:15 PM   #27
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,367
Default Re: 8ba rod bearing problem

When journal sizes are odd, I'd be wanting to make sure there was no runnout anywhere. That would make sure things are still concentric with the center line of the crank. There can be a problem if journals are polished too far. Some folks used to lap the bearings too so you never know what your going to find on these old cranks.
rotorwrench is offline   Reply With Quote
Old 10-07-2019, 08:05 PM   #28
3739ford
Senior Member
 
3739ford's Avatar
 
Join Date: Feb 2017
Location: Dothan, AL
Posts: 325
Default Re: 8ba rod bearing problem

I removed the pistons/rods with bearings and have everything ready to go back to the machine shop tomorrow. I'm going to see what he figures out and tells me what the problem is. With my cheap measuring tool it seems to me the rod journal is not round, but more egg shaped. Will let you know what the outcome is.
3739ford is offline   Reply With Quote
Old 10-07-2019, 08:56 PM   #29
Gene1949
Senior Member
 
Gene1949's Avatar
 
Join Date: Jun 2016
Location: Pahrump, NV
Posts: 372
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by 40 Deluxe View Post
Wait a minute Gene. Apparently this crank was ground in the distant past when it was common to do this. Either by customer request or the crank guy wanted to save a little wear on his grinding wheels. The engine apparently ran a long time set up this way, so it was not a problem; nothing overlooked.
Precisely my point (distant past), customer request or "saving some wear on his grinding wheels" is a patch job.

Eyeballing a "polish" on a crank without measuring it is not something a reputable shop would do.
I doubt if the crank even had a bath after the polish.
The owner himself picked up on the original patch job (grind) AND egg shaping the journal, who knows.
Gene1949 is offline   Reply With Quote
Old 10-08-2019, 08:10 PM   #30
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,009
Default Re: 8ba rod bearing problem

I think you answered your own question when you measured the journals - two are at .020 and two are at .030 . . . a miss-matched affair. Now, if the journals are in good shape, concentric, no taper, etc -- then I can see no real issue with running .020 bearings on two journals and .030 on the others. Would I do it this way . . . well 'No' - but I'm a perfectionist and I wouldn't want the "next guy" to see an engine I built done in this fashion.

BUT - with all that said, if it is about spending less money - then you can probably put it together with the two different rod-bearing sizes - as long as the resulting clearances are correct.

On my Soapbox: What is still of concern is that the machine shop obviously didn't measure the crank . . . so what else didn't they measure? Quality machine work and correct clearances are everything in an engine build . . . .
Bored&Stroked is offline   Reply With Quote
Old 10-08-2019, 10:39 PM   #31
Pete
Senior Member
 
Pete's Avatar
 
Join Date: May 2010
Location: Wa.
Posts: 5,373
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by GOSFAST View Post
Very accurate statement here, not only on an individual rod journal but sometimes an occasional cylinder bore also! (See photo below, it's just one brand of a "portable" boring bar used at the time for very this purpose)

Many of these type repairs were done with the engine still in the ride, it's how it was done back then!

Thanks, Gary in N.Y.

P.S. At one time I had the "portable" crank grinder along with the boring bar pictured here, I still own this bar, the crank grinder went a long time ago. In retrospect it wouldn't have hurt to hang on to both?? Nice conversation pieces today anyway! I have customers today have absolutely no idea what the bar was used for when I show it to them?
As a side note Gary, Rottler is having their annual open house to the industry this weekend. Everybody will be there. I first met the old man in 1955.
Pete is offline   Reply With Quote
Old 10-09-2019, 06:25 AM   #32
JWL
Member Emeritus
 
Join Date: May 2010
Location: Fitzgerald, Georgia
Posts: 2,204
Default Re: 8ba rod bearing problem

As another side note, I own both a "in-car" crankshaft grinding machine and boring equipment.

I saw the crank grind done once and the operator was very skilled and efficient. The job was a new Rambler 6 cyl. that was under warranty. As far as I know it survived the warranty period and is still going. Grin.
JWL is offline   Reply With Quote
Old 10-09-2019, 07:22 AM   #33
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,009
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by JWL View Post
As another side note, I own both a "in-car" crankshaft grinding machine and boring equipment.

I saw the crank grind done once and the operator was very skilled and efficient. The job was a new Rambler 6 cyl. that was under warranty. As far as I know it survived the warranty period and is still going. Grin.
Hey John: Was sitting here scratching my head - trying to imagine how the rod journals could possibly be ground in the car (given the stroke/throws of the crank). Did this magic gismo somehow handle the rods as well? I'd love to see that machine in action! And I imagine it would take a hell of a skilled operator to use it!
Bored&Stroked is offline   Reply With Quote
Old 10-09-2019, 09:47 AM   #34
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,367
Default Re: 8ba rod bearing problem

In car work was usually done on warranty situations where the car was still in near new condition and there was less chance of heavy wear or bending on any of the rotating components. Older components with a lot of wear and tear should get more scrutiny to insure serviceability. A dedicated crank grinding machine is the best way in that situation. Checks are simpler that way and repairs would follow as necessary.
rotorwrench is offline   Reply With Quote
Old 10-09-2019, 06:10 PM   #35
Kohnke Rebabbitting
Senior Member
 
Join Date: May 2010
Location: 60615,330th Ave.,Clare, Iowa, 50524
Posts: 1,457
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by Bored&Stroked View Post
Hey John: Was sitting here scratching my head - trying to imagine how the rod journals could possibly be ground in the car (given the stroke/throws of the crank). Did this magic gismo somehow handle the rods as well? I'd love to see that machine in action! And I imagine it would take a hell of a skilled operator to use it!
It was for Rods, NOT mains.

Herm
Kohnke Rebabbitting is offline   Reply With Quote
Old 10-09-2019, 07:49 PM   #36
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,009
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by Kohnke Rebabbitting View Post
It was for Rods, NOT mains.

Herm
Hey Herm - just checking . . . RODS, not mains??? I can see a fixture for the mains working, but the rods - that has to be complex! It would have to somehow rotate/articulate with the crankshaft rotation - that seems to be a hard situation to ponder - unless it indexed off the mains in some fashion.

Just curious!
Bored&Stroked is offline   Reply With Quote
Old 10-09-2019, 09:44 PM   #37
Kurt in NJ
Senior Member
 
Kurt in NJ's Avatar
 
Join Date: May 2010
Location: on the Littlefield
Posts: 6,140
Default Re: 8ba rod bearing problem

The grinder has a hook opposite the grinding wheel, there was a motor to turn the rear wheel, or fit in the place of the starter to rotate the crankshaft , the grinder moves with the rod journal. It can only make the journal round, but the center of the journal will move if the wear was only on one side
Kurt in NJ is offline   Reply With Quote
Old 10-09-2019, 10:16 PM   #38
Ol' Ron
Senior Member
 
Ol' Ron's Avatar
 
Join Date: May 2010
Location: Chester Vt
Posts: 8,840
Default Re: 8ba rod bearing problem

I had a crank ground in the car on a Chrysler 383. The wheel on the grinder was quite skall and the starter turned the crank with the lugd removed
Ol' Ron is online now   Reply With Quote
Old 10-09-2019, 10:21 PM   #39
Kohnke Rebabbitting
Senior Member
 
Join Date: May 2010
Location: 60615,330th Ave.,Clare, Iowa, 50524
Posts: 1,457
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by Bored&Stroked View Post
Hey Herm - just checking . . . RODS, not mains??? I can see a fixture for the mains working, but the rods - that has to be complex! It would have to somehow rotate/articulate with the crankshaft rotation - that seems to be a hard situation to ponder - unless it indexed off the mains in some fashion.

Just curious!
The best one was built by Sunnen, Model KN, look on E-Bay. It was made to be used just for Rods mostly when just one pin went bad. You jacked the car up, pulled the pan, put an electric motor and V-belt to turn the crank, the machine was clamped to the pinand the metal was ground the main part of the pin, and centered of, I Think ????????? off the Radius to keep the same stroke.

Herm.
Kohnke Rebabbitting is offline   Reply With Quote
Old 10-09-2019, 10:58 PM   #40
Kohnke Rebabbitting
Senior Member
 
Join Date: May 2010
Location: 60615,330th Ave.,Clare, Iowa, 50524
Posts: 1,457
Default Re: 8ba rod bearing problem

Quote:
Originally Posted by rotorwrench View Post
Ford allowed more clearance on the connecting rod big end bearings than they did the mains. My old Mercury manual lists .0005" to .003" for rod big end bearing clearance and .001" to .0026" for main bearing clearances. Side play on the rods is .006" to .020" for two rods on one crank pin.

Most bearing books have a maximum, and minimum for any given crank. On say a 2" crank, the actual minimum size should be .002 thousandths, and plus, one more .000-50 for a maximum.

If you set a 2" crank clearance to .000-50, or even a .001, the crank when hot will expand about .002 thousandths. So what happens is the crank pushes bearing material out of the way until it has the clearance it wants to get enough oil to the bearing to cool the bearing, and stop its expansion, so why waste bearing material, and taking a chance on smearing a bearing.

Depending on how fast the car is driven, most of the time will determine what the bearing clearance will be when, Cold, or Hot.

Herm.
Kohnke Rebabbitting is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 09:44 AM.