243431 parts avalibility?

[mwells]

Hi guys, I'm rebuilding a 10hp Briggs in my big ten and need a 10 over piston and 10 under rod, but there are NLA from Briggs. I was just wondering if there is another source for these parts or if you just have to find good used? Any input would be appreciated! Thanks!

[hurleyii]

I'd search ebay for the engine lots of stuff should come up

[mwells]

Tried eBay already. No luck:(

[Chris727]

I would bore it to .020 before using used rings...

[GrincheyOne]

Hi Mike,

I have a whole engine, minus S/G, and carb. It is bored 0.10 over, and the crank is turned down. Interested?

Vintage 1968.

[damon91]

If I remember right, when I did my engine the .020 piston is still available, I had one ordered through a local dealer. Rods were harder to find though, I had to wait until a NOS undersized one came up on ebay, I think I was lucky to find one. If you have some old dealers near you it might not hurt to call around to see if they have any old stock laying around.

[dentwizz]

I used to have a dealer parts guy who had generic rings sourced out by size not part number. I couldn't get him to reveal his source and he moved to Alaska, but you may have luck just searching for a size-appropriate ring.

[Delerion02]

I know this forum is old... I just got poppy's big ten running last year. In the middle of winter i was pulling the kids on a sled and my piston blew a hole in itself. So I have it torn down, there is a grove down the cylinder. From my understanding the 243431 should be bored to 3 1/16. I bought a micrometer and I was getting measurements less then 3.065 so I returned it and went to use a friends. The top of the bore was measuring as 3.056 with his. I think I should get it re-bored but I feel like I'm missing something and don't want to mess up. BTW: Im very wet behind the ears!

[Bill725]

The only oversize piston assembly (w/rings) available from B&S is 0.020" oversize, P/N 792363. The only connecting rod available from B&S is standard, P/N 592158. The NLA 0.020" undersize connecting rod P/N is 390305. Bought mine off eBay. If the crankshaft journal is bad and cannot find the undersize rod, you will have to use a new crankshaft, P/N 690530.

[MrSteele]

Sort of off topic, but. The best solution I have found for keeping these old machines running with the old engines, is to get one running, put it on and use the tractor, while you find parts and/or money to build a spare. When you have major problems with the running engine, swap. Now you have a running engine, and time to properly take time to build the other. I have been gradually finding parts for a ZZ to put on a tractor for a couple of years, because the one on it has a knock, which I assume(hope) is the wristpin in a cracked piston since it gets quieter with heat of running.

This gives you time to search Ebay, look for parts locally, go to auctions, etc, to find what you need.

[Delerion02]

MrSteele that is a very good idea, I was fortunate to find a 23D for $25 to pop in while I figure out my 10hp. Also kinda off topic but in your signature about your '65 Landlord the original was 23D? and not the 10hp in the '65 big ten?

But back to my original question 3 1/16 is 3.065?

So am i just finding bad micrometer if im measuring 3.056?

And what should I have the cylinder bored to?

[Chris727]

1 / 16 = .0625 so 3 and 1/16 = 3.0625

[Bill725]

B&S 10HP standard bore size diameter is 3.0625 max - 3.0615 min. 0.020 oversize = 3.0825 max - 3.0815 min.

[Delerion02]

So if there is a min and a max, would I ask for 3.0620 so I would have a tighter fit?

[Bill725]

The B&S Service Manual specifically states under Resizing Cylinder Bore, "ALWAYS RESIZE TO EXACTLY .010” (.25 mm), .020” (.51 mm), OR .030” (.76 mm) OVER STANDARD BORE SIZE AS SHOWN IN TABLE NO. 1, SPECIFICATIONS. If this is done accurately, the stock oversize piston and rings will fit correctly and proper clearances will be maintained."

The purpose of the rings is to create a seal between the cylinder wall and piston. The purpose of the piston is to support the rings in the cylinder. In this case, the cylinder is made of cast iron and the piston of aluminum. The two dislike materials have different thermal expansion properties and the clearances is based on years of research & development by engineers. My strong suggestion is to follow the B&S Service Manual.