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 10-17-2019, 04:21 PM   #1
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default RTH - Crankshaft bearing sizes

Spoke with my machinist today, and he mentioned there was a problem with the crankshaft bearings. Here are the particulars:

1. C69 block (supposedly 100 Hp version)
2. Standard crank (90 Hp version) with reground journals, but not sure of size.
3. Company that reground the crank supplied the bearings to match crank

The problem:

1. The crank bearings do not fit the block and main caps. The inside width between the flanges is 0.030" too narrow.
2. Appatently Ford changed the bearing/ block size for 100 Hp rated engines vs. 90 Hp rated engines.
3. They found a set of "correct" bearings in California, but by the time they get here, cost is approx CAN$600!

Has anyone had this issue, and if so, what did you do? Machinist is checking with shops to see if it is "customary" to shave the bearings to fit, but this requires building a fixture on a lathe to turn down the thickness of the flanges.
Ziggster is offline   Reply With Quote
Old 10-17-2019, 04:41 PM   #2
GOSFAST
Senior Member
 
GOSFAST's Avatar
 
Join Date: May 2010
Location: Long Island, NY
Posts: 928
Default Re: RTH - Crankshaft bearing sizes

Quote:
Originally Posted by Ziggster View Post
Spoke with my machinist today, and he mentioned there was a problem with the crankshaft bearings. Here are the particulars:

1. C69 block (supposedly 100 Hp version)
2. Standard crank (90 Hp version) with reground journals, but not sure of size.
3. Company that reground the crank supplied the bearings to match crank

The problem:

1. The crank bearings do not fit the block and main caps. The inside width between the flanges is 0.030" too narrow.
2. Appatently Ford changed the bearing/ block size for 100 Hp rated engines vs. 90 Hp rated engines.
3. They found a set of "correct" bearings in California, but by the time they get here, cost is approx CAN$600!

Has anyone had this issue, and if so, what did you do? Machinist is checking with shops to see if it is "customary" to shave the bearings to fit, but this requires building a fixture on a lathe to turn down the thickness of the flanges.
Hi "Zigg", the later Flathead's uses a narrower thrust flange but only on the inner rails. The measurement is 2.065" between the flanges on this setup.

On the earlier blocks they were wider, 2.095" between the flanges.

You have the main brg set for an 8BA, it can be machined to fit the early block but it isn't all that easy.

Thanks, Gary in N.Y.

P.S. You are correct, it would take a bit of "fancy" lathe work with a decent fixture. We've done a few here but only when we couldn't get the right part numbers quick enough!
GOSFAST is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 10-17-2019, 05:43 PM   #3
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Thanks very much Gary. So is what you are saying is that they (crank grinder) got a set of bearings for a 8BA type block instead of bearings for a C69 block, and that should be "common"?
Ziggster is offline   Reply With Quote
Old 10-17-2019, 06:24 PM   #4
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 10,306
Default Re: RTH - Crankshaft bearing sizes

The C69 engine has a rather uncommon bearing type. I guess that was the result of the change over to full insert bearings for the con rods and all. Canada did it first before Ford USA did but then not all Canadian stuff is the same as USA stuff. The bearings are hard to find now days.
rotorwrench is offline   Reply With Quote
Old 10-17-2019, 09:25 PM   #5
Brian
Senior Member
 
Brian's Avatar
 
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 2,417
Default Re: RTH - Crankshaft bearing sizes

Zigg, It'll only be the rear main you need to change. The rear main bearing you require will be #81A- 6331, followed by a letter, which designates the undersize. You'll need to measure your main journal with a micrometer to ascertain what size it's been ground to, and find the appropriate bearing. If you post the measured size, I, or several others on here, can give you the exact part number you'll require.
You'll not need a complete set, so forget about paying $600.00 odd, you'll only need the rear main, and any number of suppliers can provide that.
__________________
Unfortunately, two half wits don't make a whole wit!
Brian is offline   Reply With Quote
Old 10-17-2019, 11:30 PM   #6
leon bee
Senior Member
 
Join Date: May 2017
Location: Arkansas
Posts: 409
Default Re: RTH - Crankshaft bearing sizes

What does "RTH" mean?
leon bee is online now   Reply With Quote
Old 10-18-2019, 01:16 AM   #7
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Thanks again for all the great info, as not much is available on the interweeb. Sorry, on another forum, we used RTH all the time. It means RealTtine Help. I just assumed it was used here as well. The machinist was supposed to have it wrapped up, but then hit this speed bump, and of course everything stopped until he can figure out what needs to be done.
I should have mentioned he has another engine/ block, and it has the same characteristics as mine, so it is not a one-off type scenario. I wish it was this type of detailed info that should be in every flathead engine build book.

Last edited by Ziggster; 10-18-2019 at 01:23 AM.
Ziggster is offline   Reply With Quote
Old 10-18-2019, 04:37 AM   #8
Mart
Senior Member
 
Mart's Avatar
 
Join Date: May 2010
Location: Solihull, England.
Posts: 5,858
Default Re: RTH - Crankshaft bearing sizes

FWIW the French motors, though they do have some 8BA characteristics do not use the 8BA rear main. 59A type fit.

Mart.
Mart is online now   Reply With Quote
Old 10-21-2019, 02:58 PM   #9
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Update: the machinist found the correct bearing at Egge. Some attached pics shaping the difference in rear main bearings. If you look closely you can see the "keyed" section is narrower on the new bearing vs the original. There is a corresponding "notch" in the block.
Original Bearing,
Attached Images
File Type: jpg image.jpg (47.6 KB, 30 views)
Ziggster is offline   Reply With Quote
Old 10-21-2019, 02:58 PM   #10
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

New bearing.
Attached Images
File Type: jpg image.jpg (47.9 KB, 25 views)
Ziggster is offline   Reply With Quote
Old 10-21-2019, 03:00 PM   #11
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Block bearing thickness.
Attached Images
File Type: jpg image.jpg (48.8 KB, 16 views)
Ziggster is offline   Reply With Quote
Old 10-21-2019, 03:01 PM   #12
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Bearing comparison. The original bearing has a wider "notch" compared to the new bearing.
Attached Images
File Type: jpg image.jpg (53.8 KB, 27 views)
Ziggster is offline   Reply With Quote
Old 10-21-2019, 03:02 PM   #13
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

I forget to mention that the "new" bearing is the incorrect one.
Ziggster is offline   Reply With Quote
Old 10-21-2019, 03:16 PM   #14
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,250
Default Re: RTH - Crankshaft bearing sizes

He just bought the wrong year bearings . . . nothing special about your situation, you just need the 39-48 style rear main. All he had to do is look at the bearing tang width in the block and cap - to know he had the wrong one.

IMHO: Since he (or the crank grinder) bought the wrong bearings in the first place, he should be the one who is buying the replacement rear main.

To the best of my knowledge, there is no 90HP crankshaft that would have EVER used the bearings the crank grinder supplied . . . so hopefully they're not making some claim along that line. The 49-53 engines all used the 'new' bearing you took pictures of - regardless of displacement or HP ratings.
Bored&Stroked is offline   Reply With Quote
Old 10-21-2019, 03:17 PM   #15
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,250
Default Re: RTH - Crankshaft bearing sizes

Quote:
Originally Posted by rotorwrench View Post
The C69 engine has a rather uncommon bearing type. I guess that was the result of the change over to full insert bearings for the con rods and all. Canada did it first before Ford USA did but then not all Canadian stuff is the same as USA stuff. The bearings are hard to find now days.
I believe this is true on only the RODS . . . not the mains.
Bored&Stroked is offline   Reply With Quote
Old 10-21-2019, 03:45 PM   #16
Brian
Senior Member
 
Brian's Avatar
 
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 2,417
Default Re: RTH - Crankshaft bearing sizes

B&S has it correct....
__________________
Unfortunately, two half wits don't make a whole wit!
Brian is offline   Reply With Quote
Old 10-21-2019, 03:51 PM   #17
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizesr

Quote:
Originally Posted by Bored&Stroked View Post
He just bought the wrong year bearings . . . nothing special about your situation, you just need the 39-48 style rear main. All he had to do is look at the bearing tang width in the block and cap - to know he had the wrong one.

IMHO: Since he (or the crank grinder) bought the wrong bearings in the first place, he should be the one who is buying the replacement rear main.

To the best of my knowledge, there is no 90HP crankshaft that would have EVER used the bearings the crank grinder supplied . . . so hopefully they're not making some claim along that line. The 49-53 engines all used the 'new' bearing you took pictures of - regardless of displacement or HP ratings.
This makes more sense, since I mentioned that he already stated the other C59/69? engine was the same, but he stated it had a "100 Hp" crank meaning it had an additional oil passage gallery. He also mentioned that the 100 Hp cranks used the older style "spinning" con rod bearings if I understood him correctly. I find all this a bit confusing as he also mentioned the "relieved" blocks were referred to as "flatheads" and the "non-relieved" blocks were referred to as "L" heads. My block has the "factory" relief cut into the block, whereas another C59/69/59A block he had did not, as well as another 8BA block he had. I can't remember if the other "100 Hp" block had the factory relief. Is there a definitive flathead engine rebuilding book that goes into this detail ?
Ziggster is offline   Reply With Quote
Old 10-21-2019, 04:41 PM   #18
Brian
Senior Member
 
Brian's Avatar
 
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 2,417
Default Re: RTH - Crankshaft bearing sizes

ANY valve in block engine, relieved or not, can be called a flathead, an L head or a sidevalve, all terms relate to the valve in block design.

Some FORD flathead 100 HP blocks were relieved, some weren't. Nothing definitive....
Canadian C69A blocks, as well as SOME other Canadian 85 and 100 HP blocks, used a double drilled throw crankshaft and lock in shell bearings in the rods. The American engines ran exclusively full floaters until the 8BA came out, when they went to lock in 'shell bearings'. The 8BA style of rod bearings/rods, differs from the original lock in bearings/rods used in Canadian pre 8BA assemblies.
As the original Canadian lock in bearings are now next to impossible to find, simply use the regular full floaters. They will directly fit.
__________________
Unfortunately, two half wits don't make a whole wit!
Brian is offline   Reply With Quote
Old 10-21-2019, 05:21 PM   #19
Ziggster
Senior Member
 
Join Date: Aug 2018
Location: Ottawa, ON
Posts: 231
Default Re: RTH - Crankshaft bearing sizes

Much appreciated. I think he was saying something to that effect. Figures it would take a Kiwi to educate a Canadian about a C69 engine. So what differentiates the different engines - 85 vs 90 vs 100?
Ziggster is offline   Reply With Quote
Old 10-21-2019, 06:30 PM   #20
Brian
Senior Member
 
Brian's Avatar
 
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 2,417
Default Re: RTH - Crankshaft bearing sizes

Us Kiwi's got our Ford products from Canada- British Commonwealth...hence my familiarity with Canadian engines

The 85-90 HP engines are the 221's 3 1/16 bore x 3 3/4 stroke
100 HP engines are the 239's 3 3/16 bore x 3 3/4 stroke.
__________________
Unfortunately, two half wits don't make a whole wit!
Brian 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 04:02 PM.