5 hp briggs crankshaft question

[tundrabeagle3]

5 hp briggs crankshaft swap

Im replacing the tapered crankshaft on my funpower type 5 hp briggs and was wondering if the older style crankshaft will fit in it?

here's a pics of the older style crankshaft, i was going to cut the end off of the flywheel side because my funpower briggs use a regular nut to hold the flywheel on.

http://thumbs3.ebaystatic.com/pict/3209159725424040_1.jpg

 

[OzFab]

Before you go buying a new crankshaft that you're not sure will work, what is the diameter of your shaft at the thin end of the taper? You may be able to machine it down. I can't see it costing too much when you consider the alternative

 

[tundrabeagle3]

unfortunately i ruined my crank trying to cut key ways into it, i tried to get it machined but the machine shops around my house don't do small jobs and they dont even want to hear about my crankshaft.

 

[tundrabeagle3]

I got the older style crankshaft to fit. It fit perfectly, the only difference was that the crank gear was welded on to the older crank. i cant get the engine to stay on, it sounds like it wants to start when i pullstart it and open the throttle wide open. I cleaned the carb and installed a new gasket.

 

[OzFab]

Did you check to see if the flywheel keyway was in exactly the same position? A few degrees either way can have a major effect

Is your cam timing correct? If the valves are operating at the wrong time the engine won't run

How are the valve clearances? If the valves don't open & close correctly, again, it won't run.

These are just a few things off the top of my head, there are plenty more...

 

[tundrabeagle3]

i remember checking that the cam timing marks were lined up and the valves were opening (not sure what correctly is) i did get it to start once with the new crank , i was revving it until i heard a pop and it died. i removed the side cover and found out that the bolts holding the rod to the crankshaft had come off (not tightened enough) and saw alot of metal grindings in the oil not sure from where... then i tightened the bolts on the rod cleaned out the oil with the metal grindings put new oil in.

 

[OzFab]

Oh crap. Those metal grindings are probably either from the crank or the conrod. Open it up again & do a visual inspection. Both the crank journal & the big end should be completely smooth. If they're not, you have some more work to do

 

[tundrabeagle3]

thanks for the help ... im going to open it up one more time if it doesnt work after this then ill have to get a clone

 

[B man]

could it be the older engine was timed differently than the new fun power? in which case the timing marks wouldnt help much.

 

[OzFab]

thanks for the help ... im going to open it up one more time if it doesnt work after this then ill have to get a clone

No you won't, just spend a bit of time examining the two cranks to make sure they're identical & the new one's not damaged. As for the conrod; even if it's toast (which I doubt), a new conrod has to be cheaper than a new engine. IMO, you're better off with a rebuilt genuine engine than a new clone.

 

[B man]

No you won't, just spend a bit of time examining the two cranks to make sure they're identical & the new one's not damaged. As for the conrod; even if it's toast (which I doubt), a new conrod has to be cheaper than a new engine. IMO, you're better off with a rebuilt genuine engine than a new clone.

Now that im not so sure about. a new 212cc predator engine would be great. but if you can fix the original. id go for that to.

 

[landuse]

could it be the older engine was timed differently than the new fun power? in which case the timing marks wouldnt help much.

I am assuming timing marks do what they are supposed to do, no matter the engine age??

 

[B man]

I am assuming timing marks do what they are supposed to do, no matter the engine age??

yes,but what if the old and possibly slightly different model had different timing? then the dot wouldn't be right on the newer engine with Possibly different timing. especially if the crank is from an older engine.

 

[landuse]

yes,but what if the old and possibly slightly different model had different timing? then the dot wouldn't be right on the newer engine with Possibly different timing. especially if the crank is from an older engine.

I see what you are getting at, but unfortunately I cannot comment on if that might be the case

 

[OzFab]

yes,but what if the old and possibly slightly different model had different timing? then the dot wouldn't be right on the newer engine with Possibly different timing. especially if the crank is from an older engine.

If that is the case then someone better study up on valve timing

 

[tundrabeagle3]

just checked the timing marks on both crankshafts and they are on the same part of the gear on both of them i found out that the metal grindings came from the bottom of my block probably cut into by the rod. im going to put some oil in it and start pulling hopefully it starts .

 

[tundrabeagle3]

just tried it again and it wont start, im going to look into getting a new clone

 

[r_chez_08]

just tried it again and it wont start, im going to look into getting a new clone

Not so fast...

Fuel, spark, compression, timing, Torque wrench!!!
Check the basics.
Get or borrow a torque wrench, else you will have a rod through the block next time. You are lucky the rod was still OK!

Fuel- Check by spraying some easy start into the intake. Should fire. Unlikely.
Spark- Change the spark plug, make sure you are getting a nice blue spark.
Compression- test with a compression tester by spinning the engine over backwards
Timing- check your cam dots and flywheel key.

If it is none of that, and nothing else seems to be the problem, then I am stumped!

 

[tundrabeagle3]

i put the flywheel key on the crankshaft with the tall side flat in the key way because it seemed to fit better, is that the proper way to install a flywheel key?

 

[r_chez_08]

I expect it varies from motor to motor, many use 'woodruff' keys. I expect it was correct, but I would have though it would be pretty obvious which way.
Is that flywheel torqued with a torque wrench?