Heymow - Lawnmower Racing Forum
Engine Help => Briggs OHV & Vanguard => Topic started by: crazycraftsman on December 06, 2012, 08:10:13 pm
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31 Cube briggs ohv.is it as simple as throwing away dogbone and weights.then just sliding the arc brass weights on.they just float on the crank???don't they spin ???? thanks
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they spin with the crank. yes its that simple if they have romovable essentrics. pull ur pan off, flywheel off, cam out, rod outa the way and pull the crank out to slide em on. then reassemble. if its a non avs.
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its non avs.so when and if they spin it goes inbetween cam lobs and got lots of block clearace.only post i could find on here was cut out grove goes towards crank.thanks
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i dont think you have to clearance anything. they are pretty small. look in performanceracingpartsbyhitch.com he has a pic of what they look like on the crank and i dont think they need clearanced for anything.
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saw them on hitches web site and ec just didnt think they were that small.going to be making a big order for my 31 ohv and didnt know how they were assembled.thanks for your help!!!
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He's saying do they just along around on the crank. No they do not don't know what holds them in place because I've never seen a set in person but something locks them in place. If not you would wipe out the can and side of the block
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They are not a direct fit to a 31ci crank, as a 31ci crank does not have removable eccentrics. You will need to have it machined for them, or get an old style 28ci L-head crank that came with the removable eccentrics.
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they spin with the crank. yes its that simple IF THEY HAVE ROMOVABLE ESSINTRICS. pull ur pan off, flywheel off, cam out, rod outa the way and pull the crank out to slide em on. then reassemble. if its a non avs.
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Thats a real nice quote you have there, but falls short on correct information. It's not as easy as "If it's a non AVS engine, remove the crank and install them. That's due to the fact that the vast majority of the cranks do not have removable eccentrics (was never factory offered in the OHV engines) and that none of the large journal 31ci cranks had them either (being an OHV specific crank, they would'nt).
Based off the posts, I am assuming I am the only one to post, so far, who has actually installed a set or 10 before.
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I have installed them on a 31 crank after I had the eccentrics machined off at my local shop. They slide on each end of the crank, lie along the large castings of the crank and are held in place with a tension pin. I had to have the weights with me so the shop could get the right size and I had to drill the castings for the tension pins. An Alternative to this would be to buy yht billett crank which is close to being balanced anyway, so you would not need the counterweights. I have ran both, and never broke a crank.
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I have some experience with this setup. A standard ARC brass weight will fit the flywheel end of the crank.The PTO end is larger in diameter. I managed to get a brass weight from Rocket Ron that fits straight on. It is necessary to machine the eccentrics off, as previously stated, drill and tap the crank counterweight to bolt the brass weights on. I also got a billet cam drive gear from Rocket Ron. Apparently the stock ones are not very strong.
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get an old 12hp flatty and steel the crank out of it. It has removable eccentrics that you can just pop off and throw the ARC weights on. Keep in mind if you are running a 31 that it wont be balanced 100% correct either as the weights are designed with the 28 piston. I ran this set up my first year racing and the motor shook pretty bad but its still running and its a good set up.
(http://i1218.photobucket.com/albums/dd405/tolesota/build%20pics%202011-2012%20mod%20x/th_7_6_11012.jpg) (http://s1218.photobucket.com/albums/dd405/tolesota/build%20pics%202011-2012%20mod%20x/?action=view¤t=7_6_11012.jpg)
This is what they looked like in my 31ci non avs motor. With the 12hp crank there is a pin on the crank on either end that locates with the pin in the brass weight.
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ALL THE 28 CRANKS ARE 1.250 CRANK PIN AND 31 HAVE 1.5 CRANK PIN SO BE CAREFUL ON WHAT YOU TRY TO SWAP!
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ALL THE 28 CRANKS ARE 1.250 CRANK PIN AND 31 HAVE 1.5 CRANK PIN SO BE CAREFUL ON WHAT YOU TRY TO SWAP!
Not all 31 cranks are 1.5 journal. All AVS cranks are. Besides if you are running ARC stuff im assuming your gonna get a rod from them too.... rod #6279 for AVS w/ 1.500 journal rod#6280 for 1.250 journal such as the 12hp cranks.
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Not all 31 cranks are 1.5 journal. All AVS cranks are. Besides if you are running ARC stuff im assuming your gonna get a rod from them too.... rod #6279 for AVS w/ 1.500 journal rod#6280 for 1.250 journal such as the 12hp cranks.
I have never seen a 31 with a 1.25 crank. Maybe someday!
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That motor in that picture came with a 1.25 crank.
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I understand it doesn't matter what the manuals say, but according to the manual it doesn't exsist. Also if you look in the oppy book a big bore oppy doesn't either! GO FIGURE! Like I said learn something new all the time! My point was for anyone to be careful not all cranks are the same!
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I understand it doesn't matter what the manuals say, but according to the manual it doesn't exsist. Also if you look in the oppy book a big bore oppy doesn't either! GO FIGURE! Like I said learn something new all the time! My point was for anyone to be careful not all cranks are the same!
Im not trying to argue with you dont think that :lol:... you do have to be careful... try to make sure you dont get a 25ci crank either OOPS I did that before i got the 12hp flatty crank, they looked similar but the piston came up .25 short of the deck... haha
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Im not trying to argue with you dont think that :lol:... you do have to be careful... try to make sure you dont get a 25ci crank either OOPS I did that before i got the 12hp flatty crank, they looked similar but the piston came up .25 short of the deck... haha
Why didn't you just use a piston spacer :confused: :D
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LOL! No i decided to go with the offset wrist pin instead :roll:
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Im not trying to argue with you dont think that :lol:... you do have to be careful... try to make sure you dont get a 25ci crank either OOPS I did that before i got the 12hp flatty crank, they looked similar but the piston came up .25 short of the deck... haha
O-NO I know you and I arn't arguing, just talking! I forgot about the 25. I guess the lession here is "It's like a box of chocolates you never know what your going to get" LOL
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hoping for peanut butter and get mint..... i hate that. lol
Could be worse, being like 8 yrs old poor your self a big ol glass of milk.... and it ends up being grandpa's white russian on christmas day haahaha
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hoping for peanut butter and get mint..... i hate that. lol
Could be worse, being like 8 yrs old poor your self a big ol glass of milk.... and it ends up being grandpa's white russian on christmas day haahaha
If ya get grandpas white russian, at least you will sleep good that night! LOL
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I as Tim has, have seen quite a few of the non avs 31's, they were built in less numbers than the avs and i think they were just made in the begining when Briggs went to 31 Ci
Some thoughts on the brass weights, I use the hollow dowll instead of the solid one, my engineers here at work say they are stronger. Two cranks came in my shop last year with broken solid pins, they simply spun around on the shaft and the motor shook like crazy.
One more thought, the plates work pretty good in a 28, but due to the heavier piston, they really need to be checked for balance with the 31's. I have posted a "How to check balance" on here at leat twice.
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sounds like a little to much fun for me.nice to find out the really info.thanks for the input.does anyone sell the 31 non avs 1.5 crank with the brass weights installed that i can buy???or balanced non billet?i dont want to take chances but $$$295 for billet crank sounds steep.wondering my different ways to go with this.
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Can you post a picture of where your engine? Like on the right side of your engine behind the starter?
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whats on the right side of my engine behind starter??
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a motor. :woo: Well where the oil dipsitck goes tells you weather or not you have an AVS... if it goes through the engine block it is an AVS if it doesn't and goes into the pan, it is a non-avs. If it isnt an AVS im pretty sure it will have a 1.25 crank journal and you can run a 12hp crank with removable eccentrics
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already measured crank for rod jornal size its 1.496.came with oilfilter in pan ,now ,flathead pan.its a 1997 non avs engine.i have took apart avs engines before..engine is all apart cleaned, line bored .20 over for new pistion rings at engine shop.finished porting ,polishing,new avs valves because they come with the grove to exept the retainer and keepers.getting ready to order billet cam,ec spings and retainers,billet flywheel,air filter and adapter,adjustable needle kit.wondering if im better of just useing billet dog bone or better of with what better options???this is my first build with after market parts but have built lots stock.flates,oppoised,28 ohv briggs.thanks for any addvise
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doesnt rons rocket sell avs counter weights for the 31?
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its not a avs motor. :bash: :bash: anyone running the billet dogbone ,cam and flywheel with sucsess???
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A 31 non avs block will accept the 28 flathead oil pan, then you use the 28 flathead crank, buy the brass syncro elininators from arc (again, check the bsalance) and you end up with a dependable engine, providing you check the timing WITH A DEGREE WHEEL, set it for no more than 30 deg advanced. This is about as low cost as you can get.
You can also weld the top and bottom of the block on a avs engine, machine it back down and bolt the 28 flathead pan on the block and again use the 28 flattie crank. This gives the thickest cam gear provinding a more reliable engine (the avs cam gear is this because of the larger sizr of the crank)
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A 31 non avs block will accept the 28 flathead oil pan, then you use the 28 flathead crank, buy the brass syncro elininators from arc (again, check the bsalance) and you end up with a dependable engine, providing you check the timing WITH A DEGREE WHEEL, set it for no more than 30 deg advanced. This is about as low cost as you can get.
You can also weld the top and bottom of the block on a avs engine, machine it back down and bolt the 28 flathead pan on the block and again use the 28 flattie crank. This gives the thickest cam gear provinding a more reliable engine (the avs cam gear is this because of the larger sizr of the crank)
just send a 28 flatty crank to Tommy and let him balance it, then use it in your 31 non-AVS. :woo:
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i got a couple 28's flatheads and ohvs but i wanted the 3 extra cubes.the crank on the 31 is beefer and the stock rod is way beefer than a 28 .the 31 also has a short skirt pistion.i got 1ooo.oo to spend on motor upgrades and looking for about 30-35 hp dependable.so the billet dogbone won;t hold up???or best send it away to get 31 balanced with arc weights or buy billet crank.when you remove the ecentrics of how do yo know were to drill the hole for dowel pin??
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THE 28 CRANK IS THE SAME STROKE AS THE 31, THE 3 CUBES ARE IN THE BORE. FIRST GET A BILLET FLYWHEEL THEN YOU WILL NEED TO FIGURE OUT WHAT IS BEST FOR YOU. ALSO REMEMBER BIG AND BEEFYDOESN'T REV AS FAST AS LIGHTER. THE BEST WAY TO MAKE A OHV LIVE IS IN THE TIMING AND VALVE TRAIN! A BALANCED AND WELL THOUGHT OUT BOTTOM END WILL KEEP IT RELIABLE. HUFFY044 HAS A FORMULA TO MAKE THEM LIVE!
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Thanks again big al... :D
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I bought a 31 non avs. From someone who had the billet dog bone with the 28 cu crank. This was not the crank with removable eccentrics. This engine has turned 7600 rpms and nothing came apart. I have seen the 31 with the arc brass weights run. In my opnion they don't run as smooth.
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I have seen the 31 with the arc brass weights run. In my opnion they don't run as smooth.
thats because they were designed for the smaller piston in the 28.
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I understand it is designed for the 28 cu piston. I would say there is a lot of people running the dog bone with success. With his 1000 dollar budget he might consider the dog bone.
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I understand it is designed for the 28 cu piston. I would say there is a lot of people running the dog bone with success. With his 1000 dollar budget he might consider the dog bone.
I agree, consider it, just keep with the basic ideas of running an OHV.
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I'm thinking of it.Wondering what i'm going to feel like when the counter weight flys throw my 200 dollar cam on the ground.If the cam survives i could care less about the 25 dollar dogbone and the block.I'll just move my cam,flywheel and valve train into one of my 28 ohvs. :D
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This engine has turned 7600 rpms and nothing came apart.
I must need to take notes!!!!!!!!!!!!!!! Who did this? I only ask because I have never turned a Briggs single very much over 7000, and the most I have ever seen was around 7400 (full tilt FX motor with EVERYTHING).
I ran the dog bone in a 28 with the flywheel when I first started. I got a lot of races out of that motor, in fact I ran it as in 2011 in FX (with a billet crank). When I took the counterweights out to replace the stock crank with the flathead crank (with removable counter balance, and ARC brass weights) I noticed that the bearing surface of the counter weight had some scarring and roughness to it. This motor was turned 6-6500 at every local race for about a year.
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It is a 31 cu briggs single. I bought it from kevin repa it has the dogbone. I have never turned it more than 6700... Although I let a fellow racer run it this year in carlise ia. He ended upside down. When I turned the mower over on all fours, pushed it back to the trailer, I recalled the tach. It said 7630. I tore it down and everything still looks pretty good.
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It's nice to here a lot of people using the billet dogbone with sucsess!! :woo:
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Are you going to use the stock 31 rod?
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i ran a billet dogbone with a stock (good) rod for three seasons on an un-governed engine with no failures whatsoever, wouldnt have bothered me at all to throw a cam in it along with a billet flywheel, but rules didnt permit it, even the 28's will shake at certain rpm's with the brass weights, on most i have seen it is low in the rpm band around 2500 rpm, but ya seldom ever see that rpm in a race engine so its never an issue, be fore warned tho if the counter weights do decide to vacate the block rest assure they will take everything with them including that high dollar cam, and dont be scared of the good briggs stock rod, George ran them a long time before arc came out with the billet rod!
i also had a 31'' with the 1.25'' crank in it, so they do exist, just not sure how common they are!
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ya the 31 rod in this engine looks likes brand new and going to reuse.Getting the engine line bored for new .20 over pistion .I can't wait till next year new engine and sand blasted complete frame, powder coated and candy apple paint on my mini craftsman.Complete mower weighted 174 pounds and it will probly drop to 160.Going to be a rocket.We have no points races up here and we have a couple racers with modifed engines so i'm hoping for so tight racing.. :D
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With a stock rod, my personal preference would be to use stock crank and weights with the arc dogbone. Keep in mind the harder you turn the motor the more is at risk.
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I'm going to use the billet dogbone this coming year and next year get the crank balanced out of a 28 cube because there way easier to get my hands on for cheap.I only seen one of these 31 non avs cubes in the last 3 years so i had to have it and the price was right at 75 bucks..It;s going to cost me 300 plus probably to ship and get balanced.
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sorry.thanks everyone for there advice and knowledge. :D :D :D
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I was reading this pst saw you said that ur 31 ci brigs. Is this the one with oil fliter that says 777 on model number Me and my freind fond one in junk yard and bought it. Iwas wondering if those are pressure lubed or not. Dose anyone know?
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Dose anyone know?
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i don't think any briggs singles are presure lube.the oil filter only cleans sump oil,and they still have a oil slinger.cheak your messages.