Childs & Albert aluminum rod search / balancing question.

New to the forum. Have had this dilemma for almost a year now. I have a 400m that I offset ground the crank to accept a 2.2 BBC rod. I'm running childs & Albert almunimum 150 series rods. Anyway the problem is one rod isn't the same. And almost 40 grams lighter on the big end. So my question is, does anyone have 150 series rods? They literally don't exist anymore. Maybe they could part with one? Also is there anything wrong with just welding on a lil weight on the balance pad of the light rod. To even up the weights. Already way too invested into it to just scrap the crank and rods. So I really wanna get this together. Thanks for any input. I'm totally stumped. I have a extra 100 series rod and I'm going to weld on it this weekend and see how much stress it will still hold. Tig welding of course.

My first thought is to drill/grind the other 7 to make them the same weight as the light one. Make 'em same weight on the pin end and the crank end.

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I had the exact same idea. I'd feel better doing that - rather than welding.

Ok 40 grams just seems like a lot of material to take away. Remember they aluminum and 40 grams is 1.4 ounces I think. But maybe meet in the middle? Weld a lil on the light one. Maybe machine it and add a weight? And then lighten the other seven? I really just want a matching rod though.
Is welding going to for sure take away from the integrity of the rod?

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Originally Posted by Tyler howe

I really just want a matching rod though. Is welding going to for sure take away from the integrity of the rod?

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Welding will definitely change the metal, it may not be a detriment at all, but it could be. And that's the real issue - you just cannot know what the base metal will do. But stresses will be induced and you'll not have many ways to even those back out.

I don't have any "heavy metal" handy to visualize what 40 grams looks like, but we have bored into a piece and put the metal into the hole, then used a threaded plug to capture the metal inside. I've done fans as large as 4 foot diameter and centrifuges as small as a toaster. A single aluminum rod presents some unique challenges. Could you add bolts in the middle perhaps? Just trying to think outside of the box..

Does C&A offer any help? Could they make one? Or, just take your chances weld to the rod and then verify alignments. Just another thought too, but after welding see if someone can shot peen it to remove any odd stresses..

Here's a chart for Mallory Metal (Tungsten) net gain for steel - Heavy Metal Net Gain Chart - Crankshaft, Camshaft, Flywheel Balancing Supplies - ABS Products
Note they say if you don't find the information you need in the chart to call them, and they can guide you through your problem. I don't think I've ever heard of using a MM slug on a rod, but the guys at ABS can probably tell you if they've seen it done.

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Originally Posted by Tyler howe

Is welding going to for sure take away from the integrity of the rod?

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Yes, of course, but so will grinding/drilling. You're left with a choice, either step up to the plate and chance it or use them for bookends.

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I think what I am going to try to do is add washers or longer rod bolts to gain the weight. No welding. No machining. Way easier if it works

Thanks for the input and the chart. Might have to use super heavy wahsers

I've been on couple road trips and haven't been here to give you the answer that will work---------Don't try welding on an aluminum rod-they are generally of an alloy that doesn't weld------also the heat, cooling etc will distort the rods shape in the diameter, twist, offset--------

You can add 40 grams to the center area of the crank throw that you'll install the rod on----if its #1 or #8 pretty much piece of cake-------a 5/64 welding rod weighs one gram per inch so you can take a couple of pieces just over 20 inches long, bend a kink at 20 inch mark and weld on----------many front and rear throws have lightening holes so is a good place to add weight back-----

and then use a bob weight that is 40 grams lighter--------

Thought hit me while unloading from long road trip while sitting on the ----- this morning------Did the OTHER 7 rods by any chance when weighed have the rod bearings in them??????? and this ONE without bearing???????? That would account for the 40 grams difference----------I've balanced thousands of crank assemblies over the last 40 years and the narrowed BBC bearing is aprox that weight-------

Or------------another thought----Is the lighter rod already narrowed to fit the Ford journal and the others are not?????

I didn't catch if the rods are a NEW set OR if there was one added at some time? Used to be typical to see a set of 7 rods for sale.... C&A probably didn't make 7 rod sets originally.

A serious problem that I've seen numerous times over the years with Aluminum rods is fatiquite cracking along the bolt threads to outside surface if they have been sitting with bolts tight-seems the pressure on the threads will split to the outside and this has been a common issue I watch very carefully with Alum rods-------(also happens to alum rocker arms under pressure from cam holding valves open with hundreds of lbs pressure)

Soooooo-------I have come to point as I go down trail of life to not leave anything aluminum under stress/strain of valve spring pressure or rods fully torqued----

[QUOTE=jerry

You can add 40 grams to the center area of the crank throw that you'll install the rod on----if its #1 or #8 pretty much piece of cake-------a 5/64 welding rod weighs one gram per inch so you can take a couple of pieces just over 20 inches long, bend a kink at 20 inch mark and weld on----------many front and rear throws have lightening holes so is a good place to add weight back-----

and then use a bob weight that is 40 grams lighter--------[/QUOTE]



Welding on the outsides of the rod journal on the crank? I am confused on what exactly you're trying to say. The rod is from Childs Albert but it's a newer model of rod that's why it is lighter.

And as far for them cracking and breaking. I feel that happens only in 2000hp rigs. These rods are rated for thag but will only see 600hp. Just had them laying around. And wanted to try a lighter stroker build

Sooooooooo--------yes you can add the 40 gr to the crank in an area equalvent to the center of the throw-----or you can balance the crank with a bob weight on the throw that the rod will be with 40g lighter-------

Butttttttttt--------don't weld on alum rod-40gr is a lot of alum---------you might be able to profile the shape of the other 7 to lighten them

But I wouldn't run alum rods on the street------why not get some new steel rods that are BBC size, ford width and whatever length you need with the pin size you want????? And be cautious with the bearings when you cut them down to clear any radius on the journal plus rod side clearance----