Tight Crank on New 10HP Briggs Rod

[bertsmobile1]

Down here it is cheaper to buy a new crank than to have an old one resized.
Crank grinding is a very specailzed job and yes finding a grinder with a small enough wheel to fit the journal can be a problem.

 

[jp1961]

Hello,

Heres just a thought without going the machine shop rout or buying a new crank.

Apply a small amount of valve lapping compound to the rod journal, and rod cap, assemble the rod and cap with the rod bolts slightly loose and rotate by hand a bit to remove several tenths i.e. .0001". Maybe an electric hand drill could be used to slowly rotate the crank?

Obviously you'd have to throughly clean everything prior to final assembly.

OK after thinking about this (and drinking a second cup of coffee,,,lol), valve lapping compound may be too coarse, but there are "cleaner" auto waxes that contain a mild abrasive that might be a better choice. There also is a product called Liquid Ebony", that is a super fine rubbing compound that removes swirl marks left by coarser rubbing compounds.

Regards

Jeff

 

[tom3]

If the crank is round I'd work on the rod. Machine shops have reamed out wrist pin bores for auto engines since forever, simple operation. Take the crank and rod down to the local NAPA shop (or whatever is handy) and let them work it out.

 

[Go-Rebels]

Fellas, remember I bought a new replacement rod that doesn't fit. I've already measured my crank journal and found it to be within specification so I'm not grinding the crank. Now I need to find a rod that fits without modification... no shimming, no lapping, no reaming. It's got to be out there.

 

[bertsmobile1]

When you tighten the rod bolts are you using a small tension wrench ?
I have a 6" wrench that reads 30 ftlbs at full scale.
I bought it particularly for doing swing back blades which are done up from 10 ftlbs to 20 ftlbs.
Also remember the torques for con rods are generally given in INCH pounds not Foot pounds.

 

[Scrubcadet10]

When you tighten the rod bolts are you using a small tension wrench ?
I have a 6" wrench that reads 30 ftlbs at full scale.
I bought it particularly for doing swing back blades which are done up from 10 ftlbs to 20 ftlbs.
Also remember the torques for con rods are generally given in INCH pounds not Foot pounds.

http://www4.briggsandstratton.com/miscpdfs/RNT/Engine Specifications Chart_ms3992.pdf

 

[Go-Rebels]

When you tighten the rod bolts are you using a small tension wrench ?
I have a 6" wrench that reads 30 ftlbs at full scale.
I bought it particularly for doing swing back blades which are done up from 10 ftlbs to 20 ftlbs.
Also remember the torques for con rods are generally given in INCH pounds not Foot pounds.

Yes, I’m using a small Snap-On torque wrench that reads in in-lb.

 

[Scrubcadet10]

I know it's a long shot, but you might call or email Briggs with your model number give them the crankpin journal spec and give them the rod part number you ordered and see if they can figure anything out.
I'd also give them your Code number.

 

[ILENGINE]

Slightly off subject, but have been seeing lot of torque specs in in/lb that are outside the setting limits of the wrench. Like 325 for sump bolts, or 370 for head bolts, or in some cases 750 in/lb for some hydro inner parts. Yes you can convert to ft/lb but if your ft/lb wrench is off accuracy by much that can mean a big error in in/lb.

 

[Go-Rebels]

I just ordered and received another rod from Amazon. It fit perfectly and no binding after torqued to 100 in-lb.

Good rod casting: "MAG 5A", cap "8C"
Bad rod casting: "MAG 3A", cap "11C"