LeMans rod bolts

[GJCAT427]

I started to do some primary work on my TP build and first was to do the rod bolt change on the Leman's rods. I had a package of nos FPP bolts stashed away and dug them out. Rods are all nos. Things went well until I discovered I`m 1 washer short in the FPP kit. Now to my surprise I discovered these are ARP bolts. I suppose I can get one if I have to but the question is are these needed? I know the ARP instructions say there used to keep the rod bolt radis from interfering with the cap. I`m thinking of just running a chamfer on the rod caps and calling it good. Its not a big deal to put the caps in my bridge port and set the down stop from taking too much off. I do this every day at work when we drill holes. Also with the washers it raises the head of the bolt 1/8" compared to the oem bolts. Possible interference one assembled? Opinions please?

[jayb]

My opinion would be to get the washer.  I'd avoid cutting on the rod cap if at all possible, even just a chamfer for clearance to the bolt shoulder.

[scott foxwell]

Washers on rod bolts are a thing of the past. I would not recommend running them. They have been known to crack and when they do, it immediately relieves the tension on the bolt and that can lead to ugly things. Your idea with the chamfer is perfectly acceptable.

[gt350hr]

   FPP always repackaged hardware from other manufacturers. I would contact ARP for a washer and call it a day. Idon't know of an ARP washer ever failing on those rod bolts.

[scott foxwell]

   FPP always repackaged hardware from other manufacturers. I would contact ARP for a washer and call it a day. Idon't know of an ARP washer ever failing on those rod bolts.

They've been known to crack on many occasions. "Those rod bolts" are hardly a consensus. Not one modern connecting rod uses washers under the bolt. There is a reason for that. It's a BAD idea.

[GJCAT427]

Funny thing is my other 427( a med riser) has FPP rod bolts in it and I do not recall it having the washers. I have had the bottom end apart twice in thirty yrs with no problems. The first time it was for a couple of pin retainers that scored the cylinders and wound up with a cracked  valley , due to the machine shop pressing the sleeves, a new NOS block was installed to fix their mistake( I still have the block), and the second time was to freshen it up about 10-12 yrs ago. It just seems to me that I can run the bolts without the washers and have the same results as my other engine. One other thing, the Lemans rods do have a slightly larger hole size than the bolt shank and being there is a dowel between the cap and the main beam , I don`t fore see any problem not using the washers. I know in structural steel washers are used for a crush tighting to "set" the torque of the bolt and nut connection. Thanks for you input guys.

[scott foxwell]

A "washer" discussion was brought up not long ago in regards to torque and how some guys seemed to be pulling threads when using a proper torque setting, especially with aluminum heads. The problem seemed to be related to, 1) better material and newer manufacturing processes making the spot faces of the bolt holes really nice and smooth and 2) the use of thread lube on both sides of the washer, thus allowing the washer to turn on the cylinder head as well as under the nut and acting more like a bearing, reducing the friction between the nut and washer. Torque values are based on a friction coefficient calculated for the specific fastener and when this 'bearing effect" occurred, the coefficient of friction was reduced dramatically leaving the torque value way off scale for the fastener and causing an major over-torque scenario. The solution was (is) make sure you don't put any lube between the washer and the aluminum head and in fact, take the washer and rough up one side a little with some 120g sandpaper and put that side against the head. The topic of washers under rod bolts also came up in the discussion and the fact that they are not a good idea. Just for some credibility, one of the people in the discussion was Tom Molnar who used to be an engineer at Oliver, started K1, and now has his own line of Molnar cranks and rods. If anyone knows Tom, he's a pretty sharp guy.

[gt350hr]

   FPP always repackaged hardware from other manufacturers. I would contact ARP for a washer and call it a day. Idon't know of an ARP washer ever failing on those rod bolts.

They've been known to crack on many occasions. "Those rod bolts" are hardly a consensus. Not one modern connecting rod uses washers under the bolt. There is a reason for that. It's a BAD idea.

     Scott ,
        I'm keenly aware that "modern " rod bolts haven't used washers for many years ( like 30). I was responding to "those bolts" that used one. Many of the So Cal locals used the ARP bolts whether purchased from FPP or not. "I" don't recall ever seeing a washer fail out here in the wild west. Your experience is obviously different than mine and noted. "I" use  the CARR bolt from Carrillo these days after I re tap the Ford rod with the exact same tap ( special thread style) that Carrillo uses in manufacturing their rods.
       Randy

[Posi67]

The ARP bolts I put in my Lemans rods 15 years ago didn't have washers. The replacement set I bought about 5 years later had washers which I thought was odd but I used them anyway. Neither caused a problem except I had to clearance my Canton windage tray for the bolts with washers. I'd be comfortable going either route.   

[wowens]

Opinions vary. If it was me and I was confident in my machinists skills, of which I am not, I would champher, can washers and go for it. OR you could buy a more modern set of bolts that don't use a washer. Then again, modern bolts may require you to chamber rods. I give up, I am giving me a headache.

[mike_burch]

I've dealt with LeMans rods.  Went to great lengths to have a good set.  The main thing with those, is the hollow dowels.  The caps are located not by the bolt, but by the fit between the dowels and registers. 

The dowels/registers wear, and the cap alignment suffers.  You can assemble them for the rod machine, do the sizing, and they look great.  Then, take them apart/re-assemble...  and they are out of whack.  Unless they are almost New Old Stock, they are VERY dangerous to work with!  I managed to get some oversize dowels.  Someone had custom made them.  I'd recommend AT LEAST taking them all apart and re-assembling to see if they change...  and strongly consider a different rod.

Good Luck!

[GJCAT427]

Yesterday I sat down and prepped the rods. I decided to chamfer the caps. It took all of 3/4 of an hr to do them. Came out fine. I feel better not using the washers. Now on to reweighing them so they can be sent with all the parts to be balanced. Oh ya HAPPY EASTER all.