Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 12-11-2020, 01:52 AM   #21
Chuck Sea/Tac
Senior Member
 
Chuck Sea/Tac's Avatar
 
Join Date: May 2010
Location: Between Seattle & Tacoma
Posts: 2,351
Default Re: Diamond B question.

Quote:
Originally Posted by Jack Shaft View Post
Big journal C crank helps too..
Down side is the rear flange the flywheel mounts to doesn’t have as much meat as the A crank. I suppose , because the flywheels were getting lighter as the roads got smoother. I was behind a friend when his flywheel flange sheared off. I don’t know if he was running a stock A flywheel, or a cut down.
Chuck Sea/Tac is offline   Reply With Quote
Old 12-11-2020, 08:47 AM   #22
Jack Shaft
BANNED
 
Join Date: Dec 2019
Posts: 1,196
Default Re: Diamond B question.

Flange's do fail. I will measure tonight against an A, will post the difference. I modify for better performance but don't race. In fact I'm quite happy with the power my modified flathead A puts out ( basically double of stock using my seat of the pants dyno), just want the long distance touring capability the B offers, I don't chase the dragon...yet .Plan on using a stock B flywheel behind the C crank and use modern fasteners with loctite to retain the flywheel. No lightened flywheel for this engine, want the mass for smooth drivability.
For racing(someday I might bump my head) I do have a late B that was bored to 4.060 and has balanced rods. I also have a 31 A block bored to .125 fitted with a beavertail A crank. The A block would get the lightest flywheel I could find, make a hillclimber..using the lightest rotating group I can muster insures fast application of torque, It might not last but will be fun while it does.
Jack Shaft is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 12-13-2020, 02:31 AM   #23
hardtimes
Senior Member
 
hardtimes's Avatar
 
Join Date: May 2010
Location: South California
Posts: 6,188
Default Re: Diamond B question.

A lot of the twisted off crank tails has to do with the crank radius being made too small.
hardtimes is offline   Reply With Quote
Old 12-13-2020, 11:26 AM   #24
Jack Shaft
BANNED
 
Join Date: Dec 2019
Posts: 1,196
Default Re: Diamond B question.

Quote:
Originally Posted by Chuck Sea/Tac View Post
Down side is the rear flange the flywheel mounts to doesn’t have as much meat as the A crank. I suppose , because the flywheels were getting lighter as the roads got smoother. I was behind a friend when his flywheel flange sheared off. I don’t know if he was running a stock A flywheel, or a cut down.
Beavertail '28 A crankshaft flange : .3875

counterbalanced ford 'C' crankshaft flange : .3875
Jack Shaft is offline   Reply With Quote
Old 12-13-2020, 11:53 AM   #25
Ranchero50
Senior Member
 
Join Date: Aug 2019
Location: Hagerstown MD
Posts: 224
Lightbulb Re: Diamond B question.

Quote:
Originally Posted by hardtimes View Post
A lot of the twisted off crank tails has to do with the crank radius being made too small.
This as any good machinist knows. Sharp edge makes a fatigue point that WILL cause a failure.
__________________
Building a '29 Speedster, the hard way...
Ranchero50 is offline   Reply With Quote
Old 12-13-2020, 12:21 PM   #26
johnneilson
Senior Member
 
Join Date: Jun 2010
Location: 34.22 N 118.36 W
Posts: 1,044
Default Re: Diamond B question.

Sponsored Links (Register now to hide all advertisements)
There are lots of issues with the crank flanges, mainly due to the slinger and resultant reduction of material where it needs to be.
Once you have seen a flange broken off the crank, and the lack of material you will really start to wonder.
Now, there is quite the debate on putting the Chev 2 pc seal into the Mod"B"/"C" cranks.
Just as many different ways of doing it also but, to reduce the likelyhood of breaking off the flange the only way is to fill weld up the slinger area and remachine for the seal.

Reducing the flywheel weight does take a lot of stress off the flange, especially if you are revving the motor up.

John
__________________
As Carroll Smith wrote; All Failures are Human in Origin.
johnneilson 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 08:29 PM.