Connecting Rod Lock Washers

[Matt Wilson]

What can you guys tell me about the history of the Dodge/Chrysler flatheads use of lock washers under the connecting rod nuts?  I have some anecdotal evidence indicating that earlier engines used these washers, and later engines did not.  I have seen two sets of 230 rods that used lock washers, one set of 265 rods that also used them, and a set of 251 rods that did NOT use them.  I suspect the 230 and 265 rods are relatively early parts, but the 251 rods are definitely from a later engine that was built in the early 60’s.

 

The reason I ask is because I am considering whether to use washers in my 265 rods, which is the original setup, vs. having the caps machined to remove the recesses where the washers reside and just use the nuts directly on the caps.  That is the way the 251 rods are set up.  The nuts on the 251 and 265 look identical to each other, and identical to some of the 230 nuts.  The reason I’m considering getting rid of the washers is on the recommendation of someone who is pretty familiar with these engines, due to a concern over the washers cracking in service, which could loosen that joint and make for a bad day if a bolt lets go.  This may make some sense, if my assumption is correct about Chrysler/Dodge dropping the washers in later years, but there is a part of me that says I should just stick with what came out of the factory.  I think virtually all engines since the 60’s or 70’s have come without lock washers on the rods, so that may be further support for this argument.

 

The same question could be asked about the main bearing caps.  I was looking at those on my old 230 last night, and I see that I put on some grade 8 washers when I rebuilt it.  I don’t have a specific memory of the mains having lock washers, but I think they must have, or else I probably would not have put any on them.  On the other hand, the 251 I recently disassembled did not have any washers of any kind under the main cap bolt heads.

 

Thanks.

[Dodgeb4ya]

I would stick with the factory designed connecting rods and not modify them.

 My 265 I rebuilt in 1974 has been running faithfully for me for nearly 40 years.

[Matt Wilson]

2 hours ago, Dodgeb4ya said:

I would stick with the factory designed connecting rods and not modify them.

 My 265 I rebuilt in 1974 has been running faithfully for me for nearly 40 years.

Good to know!  Do  you recall if you used oil or anything else on the threads of the rod bolts and main cap bolts?

[Dodgeb4ya]

I have always used engine oil on the main and rod bolts and rod nuts and nut bearing surface.

[Elwood]

Unless the torque specification explicitly calls for a thread lubricant, putting engine oil on the bolt threads before torquing the nuts will result in over-tightening, and possibly bolt breakage.

[Dodgeb4ya]

Not true^^^^^

Even ARP specifies a lube.

[Dodgeb4ya]

 I do agree lube definitely does change the torque readings. lubingof  Lug Nuts or Lug bolts can cause brake rotor warpage... I agree there!

But most all rod bolts are lubed according to what the manufacturer specifies.....( except Fiat 131S models - a mix of mazola oil and baking powder is used). 

 

[Elwood]

6 hours ago, Dodgeb4ya said:

 I do agree lube definitely does change the torque readings. lubingof  Lug Nuts or Lug bolts can cause brake rotor warpage... I agree there!

But most all rod bolts are lubed according to what the manufacturer specifies.....( except Fiat 131S models - a mix of mazola oil and baking powder is used). 

 

Which is my point: if the manufacturer specifies a thread lubricant (or a thread locker), use it.  But if no lubricant or locker is specified, using one, just because it's been done by others before, can get you into trouble.

[Dave72dt]

Not wanting to start a debate over lubing or not lubing threads, I find older repair manuals leave a lot of details out on repair processes, assuming the mechanic has somewhat of an inking of what they're doing.  New manuals on the newer engines may be more specific.  The instructors back in the day had their own preferred methods, based on their experience and passed those onto those they taught. My thought is lubing the threads will give you a more consistent torque reading  than dry threads that may have some corrosion, be a bit damaged or pitted  or stretched and you end up with parts that are not held together well.  Unless a manufacturer specifically said to NOT lube threads and undersides of fasteners, I would lube them.  Engine oil has worked well for years for this purpose.  If you're fussy, get the ARP lube.  If the bolt won't hold together lubed, you don't want it in there anyway.  Better to snap it off on assembly than when you have it running.

As far as lock washers, I've seen them with, without, both on the same engine,  rod caps that had castle nuts with cotter pins, main and rod caps that were safety wired.  I've picked broken rod bolts out of pans where the nut was still attached.  I haven't seen a lot of main bolts with lock washers but will admit I haven't seen everything yet.

[Dodgeb4ya]

IMO Lube your flathead bolts!

Done it many many times over the last 40 Years...it's the right thing to do.

[DJ194950]

without trying to get deep into this- ARP gives different specs as to torques as with and without their thread lube- they feel that is that slippery as it does affect the required torques.

I for one have always lubed head,rod and main bolts with motor oil and torqued to factory specs. Gas and diesel motors.

My opinion only- 30 years construction equipment mechanic- small and fairly large. Few engines are really touchy about this.

Oh ya, never have seen lock washers or flat for that matter on main bolts. Some may have-just my experience.

DJ

[Matt Wilson]

Thanks for the responses, guys.  I decided to call George Asche to ask about this.  I hate bugging him, but really wanted to get his perspective.  He says that if the rods originally came with lock washers, then he uses them.  He says he's done hundreds of engines over the years and never had a problem with any of the lock washers, and doesn't remember even finding a broken one.  So that's a pretty strong endorsement to use them.  Still, there must be some reason Chrysler went away from them some time in the 50's or 60's.  Maybe it's just a matter of them discovering that they aren't needed, so they decided to reduce part count and cost.  Having said all of this, I have read a number of examples of other people finding cracked lock washers, both in these flatheads and in other engines, so it's still not a 100% argument to keep them.

Also, I asked George about coatings on the threads of the rod bolts, and he said he uses engine oil and torques them to 45 ft-lbs, and has never had a problem.  I didn't think to ask him about main cap bolts or head bolts.

[Dodgeb4ya]

George is right and knows his stuff!