Torque ? regarding new Pro-Marine Rods....

[sosmerc]

Just got a set of the new top-guided rods from Pro Marine (part number 644N).
They do not come with any instructions regarding torque procedure or recommended lube. Am I to assume that one uses the same "angle torque procedure" that Merc recommends on the oem rods?
Anyone else use the new rods yet? All thoughts appreciated. (the price is sure right...if they are any good)

[steve]

the torque angle procedure from MERC !!! You will screw them up. Look up the subject rod or head bolt torque. I believe its around 30ft/lbs in 3 steps. Thats best. Don't use the angle method! Ask JSRE as well.

[sosmerc]

Thanks for the reply. Is your answer based on personal experience with these rods, or is there some other obvious reason not to angle torque?
Really bums me when the manufacturer doesn't care to provide proper instructions that might help to insure the durability of their product.
Looking forward to other replies on the subject. Thanks in advance.

[Capt.Insane-o]

Don't know who came up with the angle torque procedure, but don't use it. Take an old rod and put it in a vise and try it out and see what happens. 30 ft/lbs is the way in three steps.

[Propelled Marine]

Steve,

30lbs is what is recommended, with 271 loctite.

Have you gotten my catalog yet?

I'll give you a good deal on these rods.

[sosmerc]

Nick, is that what the manufacturer of the rods recommends?
If so, they should be told to insert a small instruction sheet. I think alot of folks would just go by the factory procedure as outlined in the appropriate Merc manual for their engine. I have always used new rod bolts and followed the Merc procedure.
But I will certainly use whatever is the correct procedure outlined by the manufacturer of the rods. Just need some confirmation of this.
Thanks!

[Propelled Marine]

Steve, I spoke with Pro Marine and this is the manufacturer's recommendation.

Yes, I agree an instruction sheet included in the box would be helpful.

[sosmerc]

Yes, I called them too. Guy on the other end said 32 ft. lbs....didn't say anything about loctite or oil on the threads...until I asked....then they said loctite. Fortunately, I have some time before this motor will be going together, so I'll gather some more responses.

[Propelled Marine]

Steve, I just spoke to a shop in Louisiana. He's been using the
Seacross rods from Pro Marine for about 6 months, and hasn't had any trouble.
He went to 35 ft. lbs. with the loctite.

[NEECAPR]

Hi Steve, Good to hear from you a few weeks back. I see you were selling off some remaining parts from the inlines. Sorry we couldn't do better for you on price. Complete redos turn out great, but, they're pretty involved.
Bolt torques: There's a lot of scatter in the answers coming back to you. I'd wait until someones like Jay Smith or US 1 give another opinion. Meantime, plan oil under the bolt heads and Loctite 271 on the threads.
I assume the bolts you have are the necked down types. These are characteristic of design concepts for high CYCLIC load joints like rod caps, wing spars, engine mounts, etc. The bolts cannot stand the cyclic load range. But, if the joint is preloaded highly enough, then the bolt's base stress may be pushing the yield stress with only a very low cyclic load and stress. The bolt can stand up to this exposure. But, if the preload is insufficient, the cyclic stress will be more than it can take and it will fail--SOON.
In all these concerns, preload is what counts, not "pretorque". A wide variation results from varying torque/preload relationships. What Merc does in the "angle torque" procedure is use the necked-down part of the bolt as a load limiter, placing the base load at the peak of the mean/range allowable stress curves for the bolt material. This happens when the last 1/4 turn is done and the bolt stretches(< 2%).
Digest version: most guys get along well with tightening to target torques. Get the right numbers. There is well refined design/materials engineering behind Merc"s recommendation- it's the ultimate for endurance.

[sosmerc]

Thanks very much for your informative reply. I have no doubt that using Merc's recommended procedure is correct when using "their" rods and bolts. My concern is that these new rods might be different in material and design and thus require a different procedure. I bought them thru Pro Marine and they are built in Japan. I was rather surprised and disappointed that the manufactured was not concerned enough to at least include a torque spec and preferred procedure.
It will be interesting to see how other experienced Merc builders handle the situation.