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Paul_B

Rod knock found: New Briggs Crank quality?

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Paul_B

I finally tore my 16hp single Briggs down that had repowered my 917 mostly due to a rod knock. I've found the crank measures .002 below the Briggs spec. The rod has .020" endplay on the rod journal and is beat up on the edges. The crank also has excessive endplay.

Has anyone ordered a new crank for a Briggs single? If so, do these require any machine work out of the box or is it a bolt together and go thing?

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HubbardRA

Rods can be tightened and a crankshaft can be shimmed. Been there, done that. It works and if you are like me and too cheap to do a complete rebuild for a problem like this, you can do it yourself and keep running it.

I know that most people will say that this is crazy, but I have done it a couple times on engines that didn't mean much to me to start with. I was very surprised that my jackleg process worked well for years, and actually did not fail while I still had the engine. Don't really know how long the modification really lasted, but it was years not months.

It only takes plastigage and a file to tighten the rod. You need to make a shim washer to remove the endplay in the crankshaft.

If there is endplay between the rod and crank, you can use a punch to upset some metal around the side of the rod to tighten up the fit on the crank.

I know this is not considered to be the correct way to fix this problem, but if you want to fix the problem without spending a lot of money, this will work, providing you do it properly.

If you decide to do this back-yard fix, then get in touch with me and I will try to walk you through it. If not, then buy the new parts and install them, or take it to a shop.

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powerking_one

Paul,

B&S never put out a spec for the conn-rod journal end play (and I do not recall any other mfg'r of small engines either). Briggs spec on the crankshaft endplay for 10-16HP cast iron singles is .002-.008". If this range was way out of spec then I could see how maybe the extra slop in the crankpin/rod might have happened. Then again, the small end of the rod/wrist pin has lots of lateral movement range on the order of 1/4" side-to-side, so I don't see how this crank/rod could have worn like you say. From my experience, .005 to .030" of cranshaft journal side play is reasonable.

Tom (PK)

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