Rod Bolts

[Jocko_51_B3B]

I just finished installing new pistons onto the original connecting rods when a question occurred to me; is it OK to re-use the original rod bolts installed on the rods? I am going to replace the nuts and split washers, but it looks like the rod bolts are press-fitted onto the rods. If it isn't a problem to re-use the bolts, I'd just as soon leave them alone. I don't see anything wrong with them. What's usually done?

 

 

[Merle Coggins]

As long as they haven't been bent, stretched, or otherwise damaged, they should be fine to reuse.

[Plymouthy Adams]

I would have to ask if you installed new upper end bushing and had them reamed to the proper diameter of the new piston wrist pin....if so, let the big dog eat..

[Jocko_51_B3B]

Merle, I see no problems with the bolts so I guess they're good to go, but Plymouthy just opened up a new minor can of worms. As far as new upper end bushings are concerned, the answer is no, I did not replace them or even check them. This is my mistake, so I'll be disassembling the rods from the pistons to see what I need to do next. My first thought is to just measure the inside diameter of the rod bushings with a caliper to see if they are in spec (.8592 -.8595 according to the manual). If they are in spec, is it still necessary to replace them? Or is it just a good general practice to replace them? What happens to an engine if the rod bushings are out of spec? Damage to wrist pins, damage to pistons, damage to rods, or noise? Can any machine shop do the bushing replacement if it's necessary?

Edited April 23, 2018 by Jocko_51_B3B
Added comment.

[Plymouthy Adams]

most shops can ream the new bushes to specs...wrist pin knocking will drive you crazy....now is the time to try and prevent this from occurring.

[Jocko_51_B3B]

OK. To the shop we go. Thanks for the warning.

[Merle Coggins]

I find it interesting that the rod caps are all off. Maybe it's just me, but I always keep the caps and rods together to avoid any mix ups.

[Jeff Balazs]

7 hours ago, Merle Coggins said:

I find it interesting that the rod caps are all off. Maybe it's just me, but I always keep the caps and rods together to avoid any mix ups.

Not just you Merle. Standard practice when I was taught 50 years ago. And back then you caught "H" if you did it any other way.

[Merle Coggins]

1 hour ago, Jeff Balazs said:

Not just you Merle. Standard practice when I was taught 50 years ago. And back then you caught "H" if you did it any other way.

 

Yup, that's pretty much why I do that too. It's how I was taught.

[kencombs]

I check the rods and caps.  If they are properly marked, there is no need to keep them together.  If they are not marked, I mark them with a center punch.  No dot for 1, 5 for 6.  Still no need to keep them together.    But, It certainly makes it foolproof to do so.  Come to think of it, maybe I should!

[Jeff Balazs]

26 minutes ago, Merle Coggins said:

 

Yup, that's pretty much why I do that too. It's how I was taught.

And you are probably old enough to remember the "abuse" you would catch if you didn't follow instructions. The old timers I worked with back then literally lived for the opportunity to give us shop rats grief over this sort of miss step. And I think 50 years later.....rightfully so. Because these are fairly old engines now there can be lots of little surprises lurking within them. Could even be that one set of these bolts is different from the rest? I once tore into a early Corvette engine that was loaded with late 50's vintage aftermarket speed equipment. I had quite a bit of trouble locating rings and things like that for it because standards had changed over the years. It ended up being apart for a lot longer than I expected because of the time it took to source these parts. The only saving grace was the orderly tear down process that had been drummed into me.

Jeff

[T120]

3 hours ago, Jeff Balazs said:

Not just you Merle. Standard practice when I was taught 50 years ago. And back then you caught "H" if you did it any other way.

I believe in today's workplace environment, a person must use a little diplomacy when correcting someone when they make a mistake...

[Elwood]

On 4/23/2018 at 4:44 PM, Jocko_51_B3B said:

OK. To the shop we go. Thanks for the warning.

 

Is your machine shop going to burnish the new bushings after they're pressed in and before they're reamed or honed to size?  Are you going to use solid or split bushings?

 

Did you have the big ends of the rods re-sized?  If so, and you change or even just press out and then press back in the old bolts, then you should check the roundness of the big ends with a Sunnen AG300 gage or similar.  If your machine shop does rod work, they'll have this gage.

 

As for conn rod bolts and nuts (and washers if designed for them), my practice is to never re-use them.  Used bolts have been stretched, and the consequences of a conn rod bolt failure can be a lot more catastrophic and expensive then a set of new bolts.

Edited April 25, 2018 by Elwood

[Jeff Balazs]

20 hours ago, T120 said:

I believe in today's workplace environment, a person must use a little diplomacy when correcting someone when they make a mistake...

Ah come on. A few beatings never hurt anyone.

[Plymouthy Adams]

14 minutes ago, Jeff Balazs said:

Ah come on. A few beatings never hurt anyone.

actually...the problem today is too few beating have taken place.....lol

[Jeff Balazs]

52 minutes ago, Plymouthy Adams said:

actually...the problem today is too few beating have taken place.....lol

Amen!

[T120]

1 hour ago, Plymouthy Adams said:

actually...the problem today is too few beating have taken place.....lol

No subtlety  involved,the message being delivered loud and clear .... lol

[ggdad1951]

ok back to topic...

[Matt Wilson]

As for rod bolts, I would usually recommend replacing them, but unfortunately, some of them are so unique, you can't find new or NOS replacements, so you have no choice (as far as I can tell) but to find the best used ones you can and re-use them.  Primarily, I'm thinking of the rod bolts from the 265 flathead engine.  Those bolts are unlike the bolts used in any of the other flatheads, and are not interchangeable with bolts from any other engine I've ever seen.  I exhausted all of the old car parts suppliers I could find, but couldn't find any NOS bolts.  I even contacted ARP bolts about making new ones, but the price would be prohibitive.  I have the 12 bolts from my 265, and I managed to find another 10 bolts, so I plan to look through them to pick the best-looking ones when I assemble the engine.

 

I spoke to my machinist, and he said it's nice to get new bolts, but most people just re-use their old rod bolts, and as long as they are not racing or doing a lot of other high-rev operations, they usually don't have a problem.

Edited April 28, 2018 by Matt Wilson

[Jocko_51_B3B]

I hadn't checked this thread for a few days and was surprised by all the comments it generated. Of course the rods and caps should be treated as a matched pair. There's no way I would mix them up. In my case, all six rods and caps are stamped 1 through 6 on both the rods and the caps so there was no danger of a mixup. On top of that I placed the parts from each of the six piston assemblies in their own separate sections of a six compartment tray so nothing would get mixed around between assemblies. I'm not saying I haven't made my share of dumb mistakes but let's not pull out the rubber hoses yet! If you'll wait a while, I'm certain an opportunity will pop up! As far as the rod bolts are concerned, they all looked OK to me but just for extra insurance I asked a real mechanic buddy to take a look. He said they looked fine so I'm just going to go with the ones I have. I do have NOS split washers and nuts however from VPW and will be using them.

One more thing: the shop manual calls for torquing the rod bolt nuts to 45 to 50 foot lbs but doesn't specify whether they should be torqued dry or with some lubrication on the threads. I've heard opinions about this both ways. (I'm leaning toward the idea of putting some assembly lube on the treads and backing off on the torque about 20%.)  Does anyone have the absolutely right answer? I don't want to fool around with this and have the rubber hose police after me again!

 

Edited April 28, 2018 by Jocko_51_B3B
to add a comment

[Matt Wilson]

Regarding the rod washers, I had also gotten some washers from VPW, and they were too large.  They looked kind of close but they didn't sit properly in the recesses of the caps.  So make sure yours fit correctly into those recesses.  That was just last year, and the washers for the 265 are the same as for the other flatheads.

 

A for the nut torque, I spoke to George Asche, who has rebuilt literally hundreds of these flatheads in his long life, and he said he applies engine oil to the threads and torques up the nuts to 45 ft-lbs.

[Jocko_51_B3B]

My washers seem to fit Ok. Thanks for the nut torque spec. Good information.

 

(Correction!: the split washers do NOT fit. Please see my post below.)

Edited May 3, 2018 by Jocko_51_B3B
Correction

[49D-24BusCpe]

8 hours ago, Matt Wilson said:

Regarding the rod washers, I had also gotten some washers from VPW, and they were too large.  They looked kind of close but they didn't sit properly in the recesses of the caps.  So make sure yours fit correctly into those recesses.  That was just last year, and the washers for the 265 are the same as for the other flatheads.

 

A for the nut torque, I spoke to George Asche, who has rebuilt literally hundreds of these flatheads in his long life, and he said he applies engine oil to the threads and torques up the nuts to 45 ft-lbs.

 

Hi Matt,

 

    Look up "High Collar Lockwashers" in the Search field (upper right hand corner) of this site!

 

Walt

[Matt Wilson]

Hi Walt, I did the search just now, and I  remember seeing that post before.  The thing that strikes me is that someone else chimed in and mentioned exhaust lock washers, thinking they were the same as the ones you mentioned, and thinking they were the same as the lock washers used on our rods, but I'm pretty sure those exhaust washers are what VPW had, and they turned out not to be correct.  I just caution the buyer of any such washers to be observant to see how the washers fit.  It's not difficult at all to tell if you have incorrect ones.  It was fairly obvious that the ones I bought were not correct, when I test-fitted them, as they did not fit down into the rod cap washer recess.

[Jocko_51_B3B]

I took a second look at the split washers I got from VPW. Sure enough, they are too large. So I called VPW to see if they were aware of the problem. They are aware of it, but they claim that several different styles of Dodge flathead rod caps exist. According to VPW, some rod caps have recesses for the washers and some don't. VPW says they've searched for a washer size that will fit the cap recess but haven't been able to find a suitable replacement. Looks like I'll be re-using the old split washers for now. If anyone finds a source for these washers, please post it. Seems there's a demand for them.

Edited May 3, 2018 by Jocko_51_B3B
Correction