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B & S head gasket

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B & S head gasket

Postby Ron » Tue Aug 28, 2018 8:36 am

Briggs 331877 2371-g5 calls for 794114 head gasket. I have a 796584 in stock that looks to be exactly the same except for the one little solid piece that is on the left side facing the engine. it is between bolt 3 & 7 (torque tightening sequence) on the 79114 gasket and between 7 & 3 on the 796584 gasket. That solid piece doesn't look to serve any purpose from what I can tell. Google images and you can see what I mean. Just trying to finish up job as I have no other parts to order at this time.
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Re: B & S head gasket

Postby 38racing » Tue Aug 28, 2018 8:47 am

Is the bore exactly the same? There is another thread about those 2 gaskets. Briggs has mistakes(assumed) in ipl for a 31 that had 794114 listed and I bought it in error for a 31. I don't currently have a 796584 to compare it to.
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Re: B & S head gasket

Postby Ron » Tue Aug 28, 2018 9:14 am

yes, the bore is the same. If i lay them on top of each other they are exactly the same except the location of the solid piece.
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Re: B & S head gasket

Postby KE4AVB » Tue Aug 28, 2018 10:25 am

Looks can be deceiving that why they make micrometers. Sorry they are NOT the same bore. I have both new gaskets in stock here.

310000 [31 cu in] series is 3.6325 and the 330000 [33 cu in] series is 3.7725 at the cylinder opening on the gasket; of course, my mic has sharp edges so the graphite gives a little. Putting a 31 gasket on 33 can have the piston hitting the gasket plus have very gasket failure between the cylinder and the push rod galley and a 33 on 31 can lead to very early gasket failure between the cylinder and the push galley.

Edit: Added info just to make the point clearer.

310000 Standard cylinder bore is 3.563 in. (90.50 mm)
330000 Standard cylinder bore is 3.701 in. (94.01 mm)
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Re: B & S head gasket

Postby KE4AVB » Tue Aug 28, 2018 10:41 am

Also Ron you need to download the Single OHV service manual for these specs are in the section 12 of this manual.
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Re: B & S head gasket

Postby Ron » Tue Aug 28, 2018 7:21 pm

Thanks, I'll get the proper head gasket. No use in taking a chance. I do have the the manual downloaded.
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Re: B & S head gasket

Postby 38racing » Mon Sep 17, 2018 8:04 pm

I'm just checking the condition of a 31g777. I see that the head gasket bore was greater than cylinder. It matches the 794114 that I bought by mistake. Miked at 3.762 The IPL I have correctly lists 796584 as the head gasket so someone put the wrong one in. Valve cover says the engine is 2011 2014 IIRC although it was on what I think is a 2004 mower. This engine was seized. It took some work to remove sump. I ended up making a puller from angle iron and long 3/8 bolts into chassis mounting holes. Magneto end wasn't seized. At PTO there was slight aluminum transfer to the crank which I was able to clean up. to just see if it will run I may actually use the 794114 gasket for now since I may never use it. The one on it is damaged at galley point . On outside for sure. Usually outside looks ok there and inside is blown.
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Re: B & S head gasket

Postby 38racing » Tue Sep 18, 2018 2:41 pm

Any idea why there still are no aftermarket head gaskets, sump gaskets or piston rings for the briggs 31 series? Lots of those engines out there.
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Re: B & S head gasket

Postby StarTech » Tue Sep 18, 2018 2:47 pm

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