project update and questions...


http://209.208.111.198/Topic43191.aspx 		Print Topic | Close Window

By Dan - 15 Years Ago
Well not too much to update lately as we are waiting for some parts to arrive but I do have a question...

What should the rod caps be torqued too?? the engine spins over real smooth but the kids torqued the caps to 40 ft pounds and it locked up tight as a drum?? they loosen the rod cap bolts and it rolls just fine again??? 99% sure all the caps are on correctly, everything got put back in right spot, etc.

I need some ideas here, thanks-

By chiggerfarmer - 15 Years Ago
Motors book says 45 - 50 ft pounds for rods, so you are not too tight there. I think it would tend to compromise the integrity of the bolts rather than distort the rods if you over tighten a little. I would double check that 1% on the caps first, looking for one on wrong, then see if you can narrow it down to one rod by loosening them one at a time. Make sure that the bearing inserts are the right size for the crank journals, of course. When I first began engine work

years ago, it was popular to use Plastigage to check bearing clearance. I haven't looked for any lately, but it worked well. The best of luck with your project.
By aussiebill - 15 Years Ago
Dan (4/27/2010)
Well not too much to update lately as we are waiting for some parts to arrive but I do have a question...

What should the rod caps be torqued too?? the engine spins over real smooth but the kids torqued the caps to 40 ft pounds and it locked up tight as a drum?? they loosen the rod cap bolts and it rolls just fine again??? 99% sure all the caps are on correctly, everything got put back in right spot, etc.

I need some ideas here, thanks-

Dan, proggressive torqueing 20,35,45 does it for me, but check rods are in right way round; that the bearing edge is not biting on crankshaft journal radius, you will see bearing insert is set with more clearance on rod edge and this faces the journal radius. Just a thought. best regards bill.

By Dan - 15 Years Ago
Well, we got everything loosened up and checked and started retourqing everything...went good until the very last bolt and it broke...I've kept a pretty good eye on the kids and they are doing everything right, maybe we just arent used to working on 50 year parts??? So we will replace it and keep moving, the next one we do will definately have all new rod bolts...

Thanks for the help!

By PWH42 - 15 Years Ago
Is your torque wrench a known good one?
By Ted - 15 Years Ago

With students, I’ll be more inclined to trust a ‘clicker’ toque wrench rather than the ‘beam’ style.  But as has been brought up, having a 'known' torque wrench is also important.  Over three years old and used regularly makes any style of torque wrench in need of an accuracy check.  I’ll also recommend not pulling the rod bolts up in steps to get to the final torque.  Snug the nuts initially so that the caps are drawn up and in place and then bring the torque up to spec in a nice slow uniform sweep until final torque is achieved.  Be sure to put a feeler gauge between the rod pairs so that the bearing halves stay true or square to the rod while they are being torqued.

 

Pulling rod bolts apart simply sounds like too much torque and if it’s happened on a single bolt, then I have to question exactly what the torque is on the other bolts.  I’ll not rule out a bad bolt but the odds are against it especially on used bolts.

By Dan - 15 Years Ago
The torque wrench is a brand new one this year (though that is not guarentee it is accurate). We have been shimming between the rod caps as we tighten them, in fact clearances there checked out real good. Think I just have to chalk this up to some bad bolts, got me a little worried but will run with it and see what happens....

thanks for the help and advise

By Speedbump - 15 Years Ago
May be just lucky but in 40+ years of building I've never broken a rod bolt.  While the engine is at that stage, I'd be very inclined to get new bolts.  It's cheap insurance.  One of the problems I discovered students have is not recognizing the click or "give" in a breakover wrench when it happens.  This is hightened when it is a lower torque like 40# with a 3/8 wrench.  Some brands worse than others, KD being the worst I ever bought for students to use.  An exercise I did before letting students torque critical fasteners was to put a bolt in a vise and have them torque a nut to get the feel of the wrench.  Another thing I learned from the USAF was the practice of "warming up" the torque wrench by breaking it a few times at the required torque before starting the process.  The tool room we had built a fixture to make it easy to do.  Don't know if it "really" helps, but it makes sense, especially when a wrench might sit for months between uses.  Good luck.
By Dan - 15 Years Ago
good info...thanks-
By Dan - 15 Years Ago
switched torque wrenches and everything seems okay - maybe that was our problem??