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larry8200

How much wear before you bore oversize?

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larry8200
How much wear before you bore oversize? And do you consider uniform wear and cylindricity (is that a word?) as important or even more important? Thanks.

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dentwizz
I would consider it to be .010 beyond standard, but in my engine I have taken a set of .020 rings and filed the gap for satisfactory results with a plain honing of the bore. To be more technical, the "roundness" of the bore is the more apt reason for doing such an operation as boring oversize. The nature of an L-head engine's thermal distribution makes it prone to warpage as compared to an OHV. Usually that only happens from rough use or overheat though.

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CarlH
The service manual for your engine will have limits for both cylinder taper and cylinder out of round. Kohler service manuals can be downloaded from the Kohler site. Briggs sells service manuals. Cylinders do not wear uniformly from top to bottom of the ring travel.

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Burntime
He is not asking over and over, he asked once on a couple of forums to get an answer. Heck, the answers are helping me learn. I can tear into any part of the tractor but have not really played with a motor yet... This is the reason for the forums! With help I swapped some parts, but the tricks are what make it last the first time. He is looking for those...

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dentwizz
Indeed. The idea of a forum is to ask questions. Without questions there cannot be answers for the members to hear or participate in.

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powermax_paul
I agree with Dentwizz. If the bore is tapered or out of round, it will never get better. Looks like a nice tractor. It's probably worth taking the block to a machine shop to clean up the bore and put in oversize rings. Just be careful you don't ridge ream too far so that they have to over machine it. Did that on my 5.0L block and they had to bore .040 oversize. Check the crank, rod bearings and seals. All depends on how much you value the tractor. Do it now and do it right and it'll be done for you to give to your kids someday. Paul

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timflury
Larry, There is a Briggs spec as far as allowable taper and cylindricity. If you choose to bore the cylinder, the oversized pistons start at .020 over. I belong to the Briggs and Stratton Yahoo group. There are a few knowledeable gurus over there that can steer you the in the right direction. I even think Ed Stoller is a member over there as well. It never hurts to gather up as many opinions as possible before you actually start wrenching.

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larry8200
Thanks for your Advice opinions Etc. Well, The shop has the bore straightened out at about 0.006" over, now to get parts. so.. new piston, rings, rod, valves, springs and keepers, tappets and gaskets.

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powerking_one
Larry, Why are you wasting additional money (IMHO)on valve springs, keepers,tappets and possibly the intake valve? If this was a 4000-8000RPM tractor pulling engine, then yes I would agree to replacing these items too. In my younger years rebuilding lots of Kohler, Briggs, Tecumseh L-head singles, these additional valve train parts were never replaced and with zero repercussions. If the intake valve face is worn a little, the shop should be able to reface it. If the stem shows wear, then yes replace it since it allows increased oil consumption. It sounds like the bore will clean up for a 0.010" oversize, but the 0.010" piston assy (OEM PN 390365) is NLA from Briggs. So you might have to bite the bullet and bore it to 0.020" over using the newest B&S PN 792367. You can check eBay for a couple of sellers that offer aftermarket rebuilt kits (off shore China/Brazil) which may be an option too for a 0.010" piston & rings like: http://cgi.ebay.com/ENGINE-REBUILD-KIT-14-16-HP-BRIGGS-320000-CAST-IRON-/350403025860?pt=LH_DefaultDomain_0&hash=item5195a5dbc4 The exhaust valve will have to come from Briggs though (PN 394436): http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150503656719&ssPageName=STRK:MEWAX:IT Tom (PK)

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larry8200
quote:
Originally posted by powerking_one
Larry, Why are you wasting additional money (IMHO)on valve springs, keepers,tappets and possibly the intake valve? If this was a 4000-8000RPM tractor pulling engine, then yes I would agree to replacing these items too. In my younger years rebuilding lots of Kohler, Briggs, Tecumseh L-head singles, these additional valve train parts were never replaced and with zero repercussions. If the intake valve face is worn a little, the shop should be able to reface it. If the stem shows wear, then yes replace it since it allows increased oil consumption. It sounds like the bore will clean up for a 0.010" oversize, but the 0.010" piston assy (OEM PN 390365) is NLA from Briggs. So you might have to bite the bullet and bore it to 0.020" over using the newest B&S PN 792367. You can check eBay for a couple of sellers that offer aftermarket rebuilt kits (off shore China/Brazil) which may be an option too for a 0.010" piston & rings like: http://cgi.ebay.com/ENGINE-REBUILD-KIT-14-16-HP-BRIGGS-320000-CAST-IRON-/350403025860?pt=LH_DefaultDomain_0&hash=item5195a5dbc4 The exhaust valve will have to come from Briggs though (PN 394436): http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150503656719&ssPageName=STRK:MEWAX:IT Tom (PK)
well , you know, I just have a lot of money to waste. I must have the way everyone wants to spend it.

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Willy
Brake the Glaze and throw a set of cast iron rings in it and button it up. You can drive yourself nutty worrying about cylinder wear. The worst thing that can happen is it might smoke a little. If it dose and you have allot of money you can always make the machine shop a little richer. I would risk about sixty bucks against 2 or 3 hundred any day. I've re-ringed about 9 or 10 various size engines and had no problems. Keep it simple and keep cheap. MHO I know a bunch will disagree with me but I get by.

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larry8200
quote:
Originally posted by Burntime
Larry, you should start a new thread of the step by step when you put it all together. When are the parts and machine shop work done?
I'm hoping to have all machine work done and parts next Friday.

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MrSteele
Let the machine shop check for wear before jumping into the cost of boring and a new oversize piston. Show them this table:http://www.smalleng.com/linked/briggsspec.pdf If you have a good set of inside mics, you can check yourself. Check the top, middle and bottom of the bore in several positions around the circumference. You will find the bottom of the bore to be smaller usually) than the top, If it has ever been overheated, it may be a bit egg-shaped. You may get by using a good cylinder hone and a new set of standard rings, and have a few more bucks to spend on something else. If you buy a spec set of rings for a Briggs cast iron, the top ring will be chrome. Chrome rings take a while longer to break in than cast or moly, but wear the cylinder walls a lot less than the others. Some folks hate a chrome ring, but I use them in everything I build, if they are available, from Flathead Fords to late model engines

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AbillC
So posts on this forum disappear without any notice, great. Every post I've made has been deleted since I joined, this one will also disappear. Screw it and you guys. And I would join this forum why? All i said was why I didn't pay for the 10 dollars, and give my opinion about rebuild.

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UCD
AbillC Your posts did not just disappear they were moved for a reason and you are aware of that reason because you were sent an email by the club President. Not every post was removed. We tolerate some disagreement but harassment is not allowed. As for you joining that is up to you and if you can abide by the rules. Your opinion is valued but when it turns into harassment it is not. This is being posted in the open because that is where you chose to bring it out.

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AbillC
quote:
Originally posted by UCD
AbillC Your posts did not just disappear they were moved for a reason and you are aware of that reason because you were sent an email by the club President. Not every post was removed. We tolerate some disagreement but harassment is not allowed. As for you joining that is up to you and if you can abide by the rules. Your opinion is valued but when it turns into harassment it is not. This is being posted in the open because that is where you chose to bring it out.
Nope, Not ONE email, didn't happen. I sure as heck wouldn't have kept posting had I known someone was telling me my posts were offensive or were considered harassment, (I sincerely apologize if they were) Nor would I have kept posting had I known someone was removing them, now would I. If it doesn't sound true, it probably isn't. Lets see the emails Mr President, This Veteran that fought for this country deserves at least the truth, I've got copies of my email records, zippo. Again, if I thought you were removing my posts, why would I, or anyone else continue to post, doesn't make sense.

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timflury
Oh man, looks like this thread started in "Talking Tractors", but somewhere it should have ended up in the "Back Room Lounge". IMHO, Mike is right, Larry could have posted his progress and if successful, his results might have made it into the "Tech Tips" area.

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larry8200
The results will have to wait untill the machine shop is done and I have all the parts, another week or more. :(!.. But I'm looking forward to it.

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