Technical torque spec for M/T aluminum rods?

puttin together an old race motor for a friend and am trying to find the torque spec for the connecting rod bolts for some vintage mickey thompson aluminum rods, the rod bolts are 7/16 fine thread allen bolts and go into the aluminum rod.

anyone?

thanks
jeff

 

I don't want to hijack Titus. I don't have the numbers you seek, but if its no trouble could you post a pic of a rod just for coolness factor? Ever since I polished up one of my B.M.E. BBC rods for my 427 gasser pipe-dream motor I seem to lust for the things.


"I need my mirror boy"

 

Probably about 75# lightly lubed. Maybe smear a small amount of white lube on a small section of the rod bolt. Shim between the rods when you torque. Either manufacture a horseshoe shaped shim the right thickness or use two feeler gauges.

 

Do your friend a BIG favor and replace those allens with a set of ARP's. A lot has been learned since those rods were made over 45 years ago.

 

75# seems excessive for a 7/16 fine thread going into aluminum? im worried about stripping out the rod.

shim? the caps have teeth where they meet each othere, there is no shimming required on these guys.

ive already researched it and arp doesnt make a bolt that will work, the allen bolts are countersunk into the rods, the od of the bolt they have is too large, even if the od was a little smaller a socket would never fit into the counter sunk hole.

I was going to say in my original post that all im asking for is the torque, dont really want opinions about bolts or the rods etc etc, this motor is not going to be raced and not revved as high as it has been in the past, not beaten on as hard either. this motor is highly modified so every part for it is custom and it has been a battle getting the all the correct parts for it and modifying existing parts to work with new since parts that would work are unavailable. its a 475 cu bored and stroked 394 olds out of an old willys gasser.

 

He's talking about shimming the thrust surfaces between the rods. Keeps everything square on the crank pin when torquing the rod caps. Not a bad practice on any engine, really.

 

Got it, never heard of that before, ive always just done regular stuff tho.

 

You can read this and see if they are talking about what you have. 60-65 ft lbs says one guy.75 ft lbs says another.
http://www.v8buick.com/archive/index.php/t-204417.html

 

Jeff,
Just looked in the 1964 Mickey Thompson Performance Handbook and Catalog. On page 34 section Connecting Rods its states: Allen head cap screws have fine threads, must be torqued to 70-ft.-lbs. for safety. A lot of people will only torque the bolts to 35 ft. lbs. which is average for studs in aluminum. They will be sorry. The object of applying 70 ft.-lbs. is to pre-load the cap screws to a tension somewhat in excess of any inertia loads that will be imposed in service. When this is done, loads on the cap screws will be constant and with rod cap held securely, there will be no fatiguing of the cap screws. Don't worry about stripping the threads in the rod; they will take more than an allen wrench can deliver. In fact, it has been demonstrated the allen wrench will twist out before the threads fail. Therefore at least 70 toot-pounds of torque should be applied

 

I ran the data through a torque calculator that I use a lot. Grade 5 bolts: 40-53 ft-lbs, grade 8, 50-65 ft-lbs. So 70 is surely close enough.

 

Thanks a ton, this is the kinda info i was looking for, i know there are alot of opinions but this is from the horses mouth per say!

thanks again
JEFF

 

I would also love to see pics of the bottom end going together. Vintage rare speed parts in a custom build, hell yeah.

 

Are they NOS , I was always told NEVER build with used Aluminum rods !!!! You never know there history ! My 2cents

 

I have a set of original Alum M/T SBC Rods and another set of Alum Super Rods with fine thread. Torqueing the super rods today to button up the new 302. My last 292 Super Rods....not too many passes, but they held together with some over revs and still look Ok.

 

German tight , good n tight ! I think , torque is by bolt thread and diameter not rod type . Should be easy to determine by bolt diameter and thread pitch


Sent from my iPhone using H.A.M.B.

 

I wonder what they were tighten to when they were first honed out too size.... I'd set up a bore gage and rod vise to find out... Start with 30 foot pounds and tighten the bolts in 5 pound increments till the bores are completely round..... Using the bore gage!!!!!
Hope that makes sense...

 

Most of these use high grade fasteners.... the MT' s have a funky offset.

Sent from my SM-J320V using The H.A.M.B. mobile app

 

Back in the "60's and "70's they called for 70# from the manufacturer.