Rods???

[Pearlsnake]

I have currently come into the possession of a 460 assembled engine missing only the carb. It has an aluminum intake, Ford Motorsports heads, .030 overbore, forged pistons, and aluminum rods. This is a balanced assembly, now my question is this, do I need to change out the aluminum rods for steel or would I be better to leave the engine as is? The motor will be in a street car (probably a late 60's Torino/Fairlane or early 70's Mustang), a manual transmission, and an occasional burnout (i.e. the engine will not be abused very often). Any advice will be appreciated.

[millennium200]

If you have quality aluminum rods you should be fine on the street as long as you do not rev the engine to high rpms untill you reach normal operating temps.

[DavidNJ]

I've heard of aluminium rods on the street but have never seen them. Aluminum is subject to high cycle fatigue. I thought they were just a drag racing thing (low number of cycles in their service life.)

Without more knowledge, I would replace them. Rebalancing will probably be expensive, since lots of mallory will be needed because of the higher bobweight with the steel rods.

P.S.
Titanium rods would minimize the weight difference, however they would probably cost $4k.

[Tom Wells]

Yo Ps,

Check here for a valid answer: http://www.460ford.com/index.php

My take on it is: not for street use!

Tom

[Jerry Clayton]

If the engine isn't in anything--I'd suggest taking a rod out and weigh it--alum is 1/3 the weight of steel, but the aluminum rod is pretty bulky and maybe not that much different than the steel rods weight- you might be able to get some steel rods nearly the same weight--the big difference would be if the aluminum rods are a special length requiring an expensive replacement--if the engine has been built up for some form of racing, does it really meet your needs? I will go thru some of my balance cards to see aprox what the weight difference is and post back here


Jerry

[Pearlsnake]

The engine was built with the intentions of being put in a early 80's truck, but the original owner quickly stepped back from this idea for fear of very poor gas mileage (which I have no problem dealing with). 11.5:1 compression, stock length rods, and my guess is roughly 400-450 horsepower (I'm leaning toward around 400) and torque is anyones guess.

Sounds like I may have to go with steel, but I'm not sure yet. Thanks for the advice.

[Jerry Clayton]

I checked several balance cards for engine types that we have built with alum and steel rods--it appears pretty consistent that the steel big end is generally about 10% heavier that an aluminum rod ahd that the recip end was generally pretty close in weight--so that would probably mean adding around 100grams to the bob weight which would be about one piece of mallory in each end of your crank

Jerry

[CarsByCarl]

Don't even think about it. Aluminum rods have a VERY limited life cycle, and they WILL break. If they are stock size, and the rpms are limited to less than 6000, you could easily throw in some stock rods and rebalance. Balance may cost a little more if mallory is needed, rods will cost $20/ea tops. I've got loads of them in storage if you want some. Or find some Eagle SIR rods for less than $200.00.

Isn't your piece of mind (and your cobra) worth $500.00? Or do you want to worry about ventilating the block and spraying the tires with oil every time you go for a drive?

[Woodz428]

Definetly replace the rods. Because of stretch it should be set up with more deck clearance, so you might check that when you change them. They are really only for engines with frequent (read race)teardowns. That's why it's easy to pick up used ones from many of the Pro racers as they try to offset the cost of replacing rods every few runs. OR.. you could keep them and listen as that tapping noise grows ever louder and the piston conforms to the combustion chamber shape, it's all in what you want.