Author Topic: Briggs 31 Non Avs VS Avs Pistons  (Read 3469 times)

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Offline cable1981

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Briggs 31 Non Avs VS Avs Pistons
« on: July 02, 2017, 11:28:10 am »
I'm trying to find a piston for a Briggs 31 non avs, pn 692273. It has been right next to impossible to find it, and was told by Briggs that its obsolete and no longer available.
Question is, can i put in a piston from an avs engine, pn 796173??
They have the same bore, only difference i can find is the avs/non avs

Offline nic_hayes

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Nic Hayes - #427 - CP/Mod-X - Small Engine Performace
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Offline nic_hayes

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #2 on: July 02, 2017, 07:02:47 pm »
Just remember you will need to have your block bored .020 over.
Nic Hayes - #427 - CP/Mod-X - Small Engine Performace
15 Time Indoor Winter Nationals Champion
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Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #3 on: July 02, 2017, 07:12:42 pm »
Will that piston work without using the billet rod? Our rules state "OEM connecting rods must be used"

Offline nic_hayes

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #4 on: July 02, 2017, 08:15:36 pm »
Is your original piston short with the thin rings like the one in the link? If it is they yes it will work. If it's the old style big piston with wide rings then no.
Nic Hayes - #427 - CP/Mod-X - Small Engine Performace
15 Time Indoor Winter Nationals Champion
2006 Kansas Outlaws Modified Class Champion
http://hayesmowersports.synthasite.com/

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #5 on: July 02, 2017, 08:39:24 pm »
I want to say it's got thick rings on it, they measure roughly 1/16 of an inch each


Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #6 on: July 02, 2017, 08:48:05 pm »
It also only has 3 rings where it's showing 4

Offline chavez

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #7 on: July 02, 2017, 11:09:35 pm »
Just use the avs rod and piston together.  The avs rod is a little better I think.  It's what the rest of the crew at Puk run in mod.
Travis Callaway

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #8 on: July 03, 2017, 11:12:48 am »
Thanks the the help guys. Now doing the 020 bore, and cleaning up the head, is that gonna change things enough to where I'm gonna have to make a timing change?

Offline nic_hayes

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #9 on: July 03, 2017, 12:08:53 pm »
Thanks the the help guys. Now doing the 020 bore, and cleaning up the head, is that gonna change things enough to where I'm gonna have to make a timing change?

No.
Nic Hayes - #427 - CP/Mod-X - Small Engine Performace
15 Time Indoor Winter Nationals Champion
2006 Kansas Outlaws Modified Class Champion
http://hayesmowersports.synthasite.com/

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #10 on: July 03, 2017, 02:40:41 pm »
Thanks guys for all the help it's much appreciated

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #11 on: July 15, 2017, 08:22:13 am »
Got the block back, put everything together, and it will not fire. I've checked recheck and checked again, but still seems like it's not getting what it needs at the right time. Any thoughts?

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #12 on: July 15, 2017, 08:30:40 am »
I used the avs piston with the avs rod, do I need to find an avs camshaft as well?

Offline outlaw#6

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #13 on: July 15, 2017, 12:22:54 pm »
No the 31 non avs cam is fine, check your timing though. Flywheel in the right position? Camshaft lined up properly?

Do you have good compression with the new rod/piston/bore combination?

Brian Reis

Offline cable1981

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Re: Briggs 31 Non Avs VS Avs Pistons
« Reply #14 on: July 15, 2017, 11:52:41 pm »
its got good compression. however a whole day working on it, the newest "wth" was fuel coming out the exhaust pipe as i tried turning the engine over.