Briggs and Stratton

buzz saw · Aug 21, 2017

Anybody have any luck staking a loose exhaust valve seat in a Briggs opposed twin engine? The old mower has a loose seat in the block, not really worth a replacement engine but too good to get rid of. I can't find any spec on the outside diameter of the seat to see how much the old seat is worn, but I know the pocket in the block being sloppy is causing most of the problem. Ordered a new seat in hopes it may be a little tighter in the block and will stake in place and do a quick grind and lap to make sure it's sealing OK. How much success can one expect on a job like this?

Janicholson · Aug 21, 2017

aluminum foil or Coors bear can might make a shi, to hold it in place long enough and with enough conduction of heat, to let it get stuck. I would stake it in as well. Jim

teddy52food · Aug 21, 2017

I would look for another seat that has a bigger OD & turn it down in the lathe to fit tight.

JD Seller · Aug 21, 2017

I have staked many of them. It works well about 75% of the time. You will not be out much to give it a try.

Russ from MN · Aug 21, 2017

I really like your reply, sounds like a shade tree engineering solution!

Duner Wi · Aug 21, 2017

I have staked flat head B&S single cyl. Worked for me but I had to grind the seat to get Ex valve to seal .

Bob M · Aug 21, 2017

I've successfully staked a loose seat back into the block on a couple B&S singles. It works as long the valve head and seat mating surfaces are in good shape.

Trick is to clamp the valve tight into the block with a suitable large clamp and spacer before staking. (I used a 1/2" deepwell socket as a spacer.) Then stake around seat evenly 2 or 3 times in a diagonally opposite pattern. This way the valve and seat will remain concentric as you stake, and you may be able to skip the grind/lap step afterward.

1130Leo · Aug 22, 2017

I just fixed one on a 8hp briggs. If the block is aluminum, and the valve seat is not damaged, simply drive it back in place, then use a punch and "ping" it all the way around it with the punch to move
the material back around the valve seat to make it stay there. It looks a little ugly, but it did work on mine. I did have to clean the valve, re gap the end play, and lap the valve. And I power
washed the entire engine, the cause of the seat popping out was due to the engine getting hot, did not realize how dirty it was under and behind the carb. Good luck.

BarnyardEngineering · Aug 22, 2017

Use Loctite 640 sleeve retainer to back up the staking.

dr sportster · Aug 22, 2017

Here is the right product for what you are doing. Way higher temp limit than Loctite.
Fluid weld

roy prins · Aug 22, 2017

1130 Leo has it right I have peened in a whole lot of valve seats and never had one come loose -- a little locktight wont hurt either --
the punch will expand the metal around the seat and tighten it in place -- goodluck ! Roy

Briggs and Stratton

buzz saw

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Janicholson

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teddy52food

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JD Seller

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Russ from MN

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Duner Wi

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Bob M

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1130Leo

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BarnyardEngineering

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dr sportster

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roy prins

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