Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

  • Announcements

    • Kent

      Sign In or Password Problems?   10/09/2016

      If you can't Sign In, you need to reset your password.  Use the Forgot Your Password link at the bottom of the Sign In screen, and the site will send you an email to reset it. If you have an AOL email account, use the Contact Us link at the bottom of the screen -- AOL is intermittently blocking email from the site.
    • Kent

      Feedback Please!   10/28/2017

      See News and Announcements forum.
BruceDP

Crankshaft

Recommended Posts

BruceDP

Does anyone know the minimum limits a crankshaft can be and still be able to take a connecting rod that is .020 undersized?

I haven't been able to find anyone local that knows.

Share this post


Link to post
Share on other sites
BruceDP

Yea, it does give the normal I guess. It also seems to state that the norm is the minimum, so it has me confused. Don't want to waist money and not fix the problem.

Just like the rod, it states the normal or new rod but seems it also says that that is the minimum, BUT, it says in the parts manual you can get a .020 undersized rod. Says nothing about the crank. I would think the same thing but don't want to chance it and end up sol.

Share this post


Link to post
Share on other sites
spyder400k

HI ok the crank can still be in tolarance under .001 but the rod needs to be perfect. it cant be oversized also. the .020 rod is aval on ebay new aftermarket. if i were you id stop by your auto parts store and get a stick of plasta gage and mic the crank and use plastia gage to see how much ckearance you do have too know for sure. just my view. but im sure they will disagree?

Share this post


Link to post
Share on other sites
BruceDP

I was told all the Briggs used the same crankshaft except some were longer than others to accommodate a front PTO. I'm assuming the larger hp engines like 10 to 20 hp. Does anyone know if that is true?

Share this post


Link to post
Share on other sites
DanD
quote:Originally posted by BruceDP

I was told all the Briggs used the same crankshaft except some were longer than others to accommodate a front PTO. I'm assuming the larger hp engines like 10 to 20 hp. Does anyone know if that is true?


id="quote">
id="quote">There were many different crankshafts available even for the same engine size. For example, I just looked in the 16 hp Briggs parts book and there are 13 crankshafts available depending on the engine type number. Having said that, the Briggs engines used in the Simplicity tractors used just the normal crankshaft...not one of the special ones listed for certain Type numbers. And, as you stated the differences certainly are something on the outside of the engine...not the size of the rod journal for example.

Share this post


Link to post
Share on other sites
BruceDP

Think you're talking a whole engine. I'd rather stay with my 16 hp front pto engine. Hard time finding a crank though. Have found one but it's not long enough to accommodate a front pto.

Thanks for the offer though.

Share this post


Link to post
Share on other sites
DanD
quote:Originally posted by BruceDP

Think you're talking a whole engine. I'd rather stay with my 16 hp front pto engine. Hard time finding a crank though. Have found one but it's not long enough to accommodate a front pto. Thanks for the offer though.


id="quote">
id="quote">The crankshaft that a 16 hp single cylinder (326400 Series) Briggs uses in the Simplicity tractor application (and is ready to accept a front PTO) is not special. It is the standard crankshaft, part number 691797.

Share this post


Link to post
Share on other sites
BLT

Here is Briggs is a std crankshaft dimensional 30 and 32 CID cut. What Briggs used is the same plus a 3/8-24 UNF X 1" deep tap.First picture std crank dimensions, second pic standard crank plus tap dimension.

32cidCrankAofB.jpg

32cidCrankBofB.jpg

Share this post


Link to post
Share on other sites
BruceDP

Thank you! My book gave me part #690534 for my model and type # from the engine but I didn't know for sure if that was the longer crank or not. Sure do appreciate it, now I have a better chance at finding the correct one.

Share this post


Link to post
Share on other sites
BruceDP

Well, finally found a crankshaft, a friend had the exact same engine and didn't know it till he let me look through all of his parts. I think I have to have it turned though and get an undersized rod. Crank measures 1.301 and if my book is correct the limit is 1.309. Can anyone confirm that? I feel like I can't trust my book.

thanks!

Share this post


Link to post
Share on other sites
powerking_one

Bruce,

My Briggs book says 1.3094" is the crankpin reject/size limit. So yes I would definitely say it would be have to be ground undersize 0.020" (assuming your micrometer is calibrated/accurate).

Tom (PK)

Share this post


Link to post
Share on other sites
BruceDP

Hey guys, went to get the crankshaft turned .020 under and he said he could turn it but wondered what to turn it down to. The only numbers I had with me was the reject size. From reading the past post here I see the correct original size was 1.311. Assuming that info is correct does that mean I need it turned to 1.291? He said he also doesn't know what they allowed for clearance. I'm just trying not to guess at this and do it right, and of course he wants the right info so he does it right and if it fails it's not his fault. He'll do what I tell him to do but I appreciate his experience and knowledge.

Thanks again for any help.

Share this post


Link to post
Share on other sites
720nut

In my opinion, If he's a crankgrinder and machinest he should know or at least know where to find the info he needs. I beleive I'ld be looking for another machinest. Just my $.02

Share this post


Link to post
Share on other sites
BruceDP

Even Briggs couldn't tell me what the spec should be. They didn't know the spec of the original standard journal size and I spoke with technical suport. They are trying to figure it out and I'm waiting for a call back. The gentlemen that can machine the crank does a lot of different things, he was recommended by a local simplicity tractor dealership. He'll do what I tell him but he's not going to do the leg work to figure out what it should be. It's just one thing he does on the side because he has the equipment and can. He also has a garage, a small airport and car lot. Very nice 56 Chevy on his lot I might add :).

Share this post


Link to post
Share on other sites
powerking_one

Bruce,

IMHO, your machinist "guy is a borderline idiot" if he can't figure out the 0.020" undersize dimension of the crank journal. New O.D. of the journal is 1.3114" to 1.3118". Minus 0.020" and there's your answer. I had some Kohler cranks ground undersize some years ago and the machinist wanted the rod too to make his measurements. Typical oil clearance is about 0.001-to-0.0015".

Tom (PK)

Share this post


Link to post
Share on other sites
BruceDP

Thanks for the help, I guess I can assume that those sizes are correct since I've gotten them more than once. Even though Briggs can't seem to come up with them. Ive never even been anywhere where they didnt have a problem with the engine numbers. Thay can never find my exact engine. As far as clearances, I would imagine different manufactures recommend different clearances depending on engine and all that but I don't know, that's not what I do. Guess I would be surprised if Chevy and Ford had the same just like I would if Kohler and Briggs had the same.

Anyway,thanks for the help, trying to find the info you need for this stuff is a real pain.

Share this post


Link to post
Share on other sites
BruceDP

Thanks for the help, I guess I can assume that those sizes are correct since I've gotten them more than once. Even though Briggs can't seem to come up with them. Ive never even been anywhere where they didnt have a problem with the engine numbers. Thay can never find my exact engine. As far as clearances, I would imagine different manufactures recommend different clearances depending on engine and all that but I don't know, that's not what I do. Guess I would be surprised if Chevy and Ford had the same just like I would if Kohler and Briggs had the same.

Anyway,thanks for the help, trying to find the info you need for this stuff is a real pain.

Share this post


Link to post
Share on other sites
Kenh

If your machinist has the new undersize rod in hand he can then grind the crank to the correct size. I was once told the fit should be a "tight" .002 fit. I would think following good engine rebuilding practice should give a satisfactory experience.

Ken

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×