08-16-2021, 08:37 PM | #21 | |
Senior Member
Join Date: May 2010
Location: Wa.
Posts: 5,405
|
Re: 4-1/8” crank
Quote:
The crush in the rod and main saddle holds the shell from spinning. |
|
08-16-2021, 08:45 PM | #22 | |
Senior Member
Join Date: May 2010
Location: NJ
Posts: 6,177
|
Re: 4-1/8” crank
Quote:
|
|
Sponsored Links (Register now to hide all advertisements) |
|
08-16-2021, 08:59 PM | #23 |
Senior Member
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,062
|
Re: 4-1/8” crank
And on aluminum rods, you usually PIN the bearing . . . to prevent it from rotating when the rod gets hot and the aluminum expands. Extra safety measure that most/many aluminum rod manufacturer's use.
|
08-16-2021, 09:07 PM | #24 |
Senior Member
Join Date: May 2010
Location: Masterton, New Zealand
Posts: 3,826
|
Re: 4-1/8” crank
'The crush in the rod and main saddle holds the shell from spinning'.
So, if the tang is merely for locating the shell, why is it that the rear main bearing, which can quite conceivably be located by the thrust faces, has tangs? I believe the tangs are an aid to prevent bearings from spinning.
__________________
Unfortunately, two half wits don't make a whole wit! Last edited by Brian; 08-16-2021 at 09:12 PM. |
08-16-2021, 09:15 PM | #25 | |
Senior Member
Join Date: May 2010
Location: East Shore of LAKE HOUSTON
Posts: 11,106
|
Re: 4-1/8” crank
Quote:
"Brian" raises an interesting point! DD . |
|
08-16-2021, 09:57 PM | #26 | |
Senior Member
Join Date: May 2010
Location: NJ
Posts: 6,177
|
Re: 4-1/8” crank
Sponsored Links (Register now to hide all advertisements)
Quote:
Interesting question. |
|
08-16-2021, 11:55 PM | #27 | |
Senior Member
Join Date: May 2010
Location: Yakima Washington
Posts: 913
|
Re: 4-1/8” crank
Quote:
Bill |
|
08-17-2021, 05:15 AM | #28 |
Senior Member
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,062
|
Re: 4-1/8” crank
There is another thing the tang does on some engines, it forces the assembler to put the shells in the right orientation (given oil holes) - typically on the rear main.
Now we all know the answer is "it depends" . . . on the engine, on how the bearing halves were made, top vs. bottom, etc. Like Pete mentioned, the location of the shells is very important - especially on race cranks with heavy fillets on the journals. The last thing you need is for the bearing shell to slip to the side, lose oil clearance and burn . . . and you'd not even know it happened until you ran the engine. |
08-17-2021, 11:50 AM | #29 |
Senior Member
Join Date: Jul 2019
Location: Southern Oregon
Posts: 782
|
Re: 4-1/8” crank
If anyone has ever seen a "spun" bearing, that is all the evidence that is needed to prove that tangs do not keep a bearing from spinning.
It's the crush that holds them, once the crush has hammered out, nothing will hold them from spinning in the housing. It's also important, that the big end of the rod, is in spec. If the rod bearing is narrow enough to clear the crank fillet, it's not hard to install them, you just make sure the bearing is on the inside edge of the rod but, not out side of it, touching the other rod, on that journal. Always check the rod side clearance, to make sure.
__________________
Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
08-17-2021, 12:04 PM | #30 | |
Senior Member
Join Date: May 2010
Location: NJ
Posts: 6,177
|
Re: 4-1/8” crank
Quote:
|
|
08-17-2021, 05:10 PM | #31 | |
Senior Member
Join Date: Apr 2019
Location: Kansas
Posts: 917
|
Re: 4-1/8” crank
Quote:
Exactly. That little tang is no match for a bearing that is going to fail due to lack of lube,overload,lack of crush,etc. I rebuild diesel engines every day for a living and we see it all the time. We've built oddball stuff and removed bearing tangs when it wasn't practical to cut notches for them...no issues at all. 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 |
|
08-17-2021, 07:03 PM | #32 |
Senior Member
Join Date: Jan 2011
Location: Central Ohio
Posts: 5,062
|
Re: 4-1/8” crank
When the bearing "welds" to the crank journal, it is going to spin . . . tang or no tang!
|
08-17-2021, 09:07 PM | #33 |
Senior Member
Join Date: May 2010
Location: Yakima Washington
Posts: 913
|
Re: 4-1/8” crank
|
08-17-2021, 10:19 PM | #34 | |
Senior Member
Join Date: Apr 2019
Location: Kansas
Posts: 917
|
Re: 4-1/8” crank
Quote:
...and that's a fact. 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 |
|
08-18-2021, 08:40 AM | #35 | |
Senior Member
Join Date: May 2010
Location: NJ
Posts: 6,177
|
Re: 4-1/8” crank
Quote:
Makes total sense now that crush and not that fractional tang holds the bearing in place. Learn something new every day. Thanks, all! |
|
08-18-2021, 05:19 PM | #36 |
Senior Member
Join Date: May 2010
Posts: 2,480
|
Re: 4-1/8” crank
Noticed the 'new' crankshafts are around $1000, and good used Merc's sell around $400. Newc
|
08-18-2021, 05:32 PM | #37 | |
Senior Member
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 10,302
|
Re: 4-1/8” crank
Quote:
BTW, "Newc", I haven't seen a good used Merc crank priced at $400 for the last 20 years. Are things better out where you are? |
|
Thread Tools | |
Display Modes | |
|
|
Sponsored Links (Register now to hide all advertisements) |
|