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slb04786

7116 with broken rod

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slb04786
Got the 7116 with 16 hp Briggs home. The rod broke near the journal and there is a lot of aluminum transfer on the crank journal. I called a local B&S dealer to inquire about getting the crank check and turned and he said "We don't reccomend turning a crank". He claimed that it is too hard to get the journal turned down to the proper soecs. He said they were getting them returned one after another with either too tight or too loose complaints. I would like to get this one turned down as a new one is over $200. Any of you guys heard of this before? What kind of results have you had in getting cranks resized? I'd like to hear your opinions. Thanks Stan The engine #'s are model 326437, type 0649, code 87050814

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powerking_one
Stan, That dealer is full of proverbial "fecal matter" telling you that, and/or his machine shop is incompetant in grinding crank journals. This proceedure is done successfully day in and day out all around the world. I'd look around for another machine shop. If a journal is out of spec (out of round, tapered, or not within maximum wear limits) it should be ground to the standard B&S undersize of -0.020" referencing the "new" diameter. Tom(PK)

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slb04786
UCD, That was what I was wondering. I called around just now and found that Carquest in Presque Isle will send it down to Bangor and have it done for $50-60. I'll have to take it in and have them send it out. Tom, Either that or the markup in new cranks is better or they use it as a toool to sell new engines. Stan

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ambler
You better find a good experienced machine shop. -.02 is standard on turning the crank. The shop I am using is turning the crank, milling the head and block top, new ball bearings, and the boring cylinder with valves and valve guides. Check with the farm boys and truck people. You don't know what all that aluminum did.

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TimJr
Ambler - what are you building. Sounds like you know your stuff, but why are you decking the block? Make sure you do some good measuring before assembly - you could easily crash a piston or valve into the head with what you have possibly removed. I learned the hard way on a 16hp Briggs. I had clearance to the head on the intake valve cold, but I underestimated the rate of expansion when hot,and bam. Live and learn, all in the name of more power! Tim

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fuzy
I don't mean to cut down another shop but we have cranks ground and cylinders bored all the time. We use a local auto machine shop that builds performance engines and really have never had any problems. Usually they are perfect. We did just have one about .001-.002 tight and they gladly ground a bit more off. Better to ground not enough than too much. I would think that any shop involved with a carquest would do a good job.

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TomMaryland
I would ditto all the posts about the shop. I was a tool and die maker for 15 yrs before getting my degree, and grinding a crank to these specs is no big deal at all. Sounds like he has a hamfisted grinder, or someone who can't read a mic.

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slb04786
Well, I took the crank into Carquest. The shop is their own shop in another city. Come to find out it is also a B&S dealer so they said they might also have the crank also in stock. I told them if they did to match them up. I felt better hearing they were associated with B&S. They also came highly recommended from an elderly gentleman that I called. He has done block and crank work on my bigger car and tractor engines so I trust him. I mentioned the name of the shop that the so called local dealer told me they used to use and he said he wouldn't take anything to those guys. So, it sounds like that dealer just needs to find another shop to do his machine work. It's too bad because he lost my parts business. I'll get my parts at Carquest now. Stan

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ambler
Tim, This is on the job training. I'm in a small engine class for mental health decided to rebuild a couplew of old cast irons. This is still farm and construction territory here so I let myself be guided by people who know. In the industrial section everyone pointed to this one shop even the small engine parts distributor. I do what he suggests. Put your hand in the hand etc. He dressed the block and milled the head. When I assemble the engine once I get the cam shaft and tappets in I bring the engine in and we machine valves to fit. One bit of advise on the major rebuild. Don't go cheap!! You need to bring the engine up to new specs or the parts you don't replace will continue to wear. What was the failure cause of the engine? No lubrication, overspeeding, overheating. That needs to be determined before the rebuild. Was their transfer at the little end? Where the fins clogged? Sludge in the slump? Good book is "how to repair briggs and stratton engines" by Paul Dempsey. Get the briggs L heads after 1981. The Clymer books have nice pictures on carb rebuild. Have fun.

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roma3112
Stan I almost hessitate to post this but>> I ran into a similar cituation with a briggs Mod 300421. Well she threw a rod due to lack ob lubrication, i took it appart and there was a fair bit of metal transfer. Now fortunately the engine had an easy life untill i forgot to put oil in it [V] nevertheless i took out the crank and was abel to polish and sand (carefully) all of the alumnium off the crank. Well I measured the crank and it was within spec :D now for the time it will take you to carefully do this and have it checked locally is it worth it ??? In my case i saved the cost of the machine work obviously i was buying a new rod anyway, I just had a moment of thrift and it worked out.

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TimJr
Most crank shops seem to be able to grind, or even just polish a journal for around $30 each - pretty cheap compared to another rod and possibly a crank and block. Hand sanding a crank is definetely not for the person who has no engine experience. Good rule of thumb is that if you have to ask if you can do it yourself, you probably can't/shouldn't. At least Roma3112 has the tools to measure and keep track of his progress. If ya know, ya know. If ya don't, educate yourself first or just open the wallet. Mechanics/engine builders love home mechanics - they often mess stuff up, so they get more money from parts or labor. Mechanics/engine builders also hate home mechanics - they mess up perfectly good stuff and then it takes up more time for a particular job, leading to a whining customer. Just my experience. Ambler - how much off the deck? Seems like a Briggs runs zero deck height stock. Are you going to let the piston pop out of the hole, or are you shaving the piston? Seems odd that a cast iron block would not be square. The head I can see warping though. Tim

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Al
Hi, We have had a lot of cranks ground. If the person does good work and checks his mic's regularly they are as good as factory. I find that most we have done are closer to the middle of the factory spec than new ones are. Just find a shop that cares. K series Kohlers and 24 and 32 cu in Briggs blocks are usually warped in the area of the exhaust valve. Normaly the only place that will need cut in the deck operation will be in this area. The rest of the deck will probably just have light tool marks on it. Decking it before boring it gets the cylinder square with the deck. The boring bar is clamped against the deck and if the deck is warped, the bore will not be straight. The whole will be straight, but not at right angles to the deck. This decking can be done in a Bridgeport or similar vertical mill, using an end mill. If done properly it will not change the piston head clearance because the only metal that will be removed will be around the outside of the exhaust valve. Just find a good shop and the result will probably be more in tolerance than the factory. My 2 cents worth, its free value accordingly. Al Eden

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ambler
The machine shop I am using is very experienced. They do most of the farm and heavy equipment around here as well as small engine work. I feel if you are undertaking a major overhaul, then the engine should be restored to as new condition. The condition of my 30 year old engines upon inspection were that one engine had insufficient lubrication and the other over heating as well as grit. Pistons scoured and cylinders out of round. Dressing the block gives you a flat surface for boring. We went 02 over. Cranks needed grinding and new bearings. Just finished rebuilding both carbs. This week begin reassembly. Insert tappets and camshafts, then into machine shop to assemble new valves in new valve seats and guides. Valve stems need to be ground for the tappet clearance as in specs. Then crank piston etc. Dressing the block and head will raise compression, probably be producing 17-18 HP out of the old girls.

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