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#1519924 - 10/19/13 10:06 AM case only difference between BB vs SB 727?
weedlayer Offline
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Registered: 01/19/03
Posts: 2866
Loc: CheddarHead till October
My new 727 has some bolt holes off. Thinking my builder built a BB instead of a SB. Have not had a chance to check things real close but suspect that is the problem. Easiest fix might be to just change the internals to my other case if I can?
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#1519925 - 10/19/13 10:09 AM Re: case only difference between BB vs SB 727? [Re: weedlayer]
Fig Offline
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Registered: 04/13/05
Posts: 167
Loc: Torrance, Ca
I'm not a 727 expert, but I cant think of one part that is not interchangeable. I lifted this off of another web site if you want to verify big or small block:

It's EASY to tell them apart if they're not attached to an engine. Course, I take for granted you can tell a 727 apart from a 904 from the pan. However, big and small block 727s are simple to distunguish. The small block version only has two torque converter dust cover retaining bolt holes across the bottom of the bell housing. The big block version has four. Of course, the bolt patterns are different, but the dust cover bolt holes are an easy fast way to tell.
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Edited by Fig (10/19/13 10:32 AM)
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#1519926 - 10/19/13 11:10 AM Re: case only difference between BB vs SB 727? [Re: weedlayer]
dizuster Offline
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Registered: 01/12/05
Posts: 2849
Loc: Oakland, MI
Only difference is the case. All parts will swap.
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#1519927 - 10/19/13 11:36 AM Re: case only difference between BB vs SB 727? [Re: dizuster]
HPMike Offline
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Registered: 05/11/05
Posts: 6443
Loc: NJ-USA
Quickest way to tell is the starter position...

If you are looking at the converter opening with the input shaft facing you, the BB has a starter position around 3 o clock...SB is lower...like 4:30 or 5 o clock...


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#1519928 - 10/19/13 01:09 PM Re: case only difference between BB vs SB 727? [Re: HPMike]
Polarapete Online   content
super stock

Registered: 05/08/03
Posts: 1134
Loc: Graham, WA
Also, the mounting bolts for the struts on the SB case require a large diameter hole at 8 and 4 o'clock
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#1519929 - 10/19/13 01:15 PM Re: case only difference between BB vs SB 727? [Re: Polarapete]
barracuda7199 Online   content
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Registered: 04/07/11
Posts: 142
Loc: GEORGIA
i always look at the dowel pin holes. small block is straight across from each other. big block the starter side dowel pin hole is higher than the other side.

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#1519930 - 10/19/13 05:43 PM Re: case only difference between BB vs SB 727? [Re: barracuda7199]
Leon441 Offline
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Registered: 11/24/04
Posts: 4102
Loc: Lynchburg, VA
Quote:

i always look at the dowel pin holes. small block is straight across from each other. big block the starter side dowel pin hole is higher than the other side.




Ya beat me to it. Also you can measure the distance between dowels openings on the case and measure the dowels in the block.
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#1519931 - 10/20/13 06:14 AM Re: case only difference between BB vs SB 727? [Re: weedlayer]
darted1 Offline
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Registered: 06/06/04
Posts: 121
Loc: LEWISTOWN PA.
If I remember correctly small block uses a bolt at the top center of bell housing to attach to the motor. the big block doesn't their top bolt holes are at like 11 0clock and 1 oclock so there shouldn't no bolt hole at the top of the big block bell housing.
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#1519932 - 10/20/13 07:17 AM Re: case only difference between BB vs SB 727? [Re: darted1]
hemibee69 Offline
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Registered: 06/17/04
Posts: 113
Loc: SE VA
That is how I differentiate small to big block bellhousing. If it has a bolt at the top in the center it is a small block. Easy and quick to see.
JiK
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#1519933 - 10/20/13 01:35 PM Re: case only difference between BB vs SB 727? [Re: hemibee69]
weedlayer Offline
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Registered: 01/19/03
Posts: 2866
Loc: CheddarHead till October
it's a BB case. I'll just move everything to my SB case. Thanks for the info.

Guess I should have looked before I drug it under the car and tried to bolt it up.


Edited by weedlayer (10/20/13 01:37 PM)
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#1519934 - 10/20/13 01:54 PM Re: case only difference between BB vs SB 727? [Re: hemibee69]
John_Kunkel Offline
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Registered: 01/20/03
Posts: 16010
Loc: Rio Linda, CA
Quote:

That is how I differentiate small to big block bellhousing. If it has a bolt at the top in the center it is a small block. Easy and quick to see.
JiK




No hole at top center.


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