Visit The Dirt Forum for More Information

Author Topic:   Aluminum Rods
Dirt Maniac

Total posts: 141
posted January 14, 2001 10:19 PM
Will they hold up in a dirt engine? Like in a flat-top 362 that turns 7200?

Dirt Freak

Total posts: 219
posted January 14, 2001 10:40 PM
That's what we have them in......a dirt mod turn about 7200 ourselves.
A few things to know, side clearance needs to be at least .045, leave the piston down the hole .012, rod bearings have holes in cap half and the rod cap has a dowel pin to keep from spinning the bearing out. and .003 to .0035 bearing clearance
The reasons for all these are as follows...

side clearance....aluminum expands at a rate twice as much as at operating temperature the clearance will be the same as a steel rod.

leaving the piston down the hole is because the aluminum rod will stretch at high rpm's
after they have stretched .020 take the out and throw them in the trash........about 20 shows depending on piston weight and rpm's

NOTICE.......bearing clearance is not twice as much compared to a steel rod. the reason for this being 1 1/2 times normal clearance with a steel rod is that the crank is steel so the expansion is only growing from the rod side to close the clearance.

Just a note, If you ran a aluminum block you would need to do the same things with the main bearings too...........

I hope I gave you ALL the information needed to understand the proper clearance and why.

Dirt Maniac

Total posts: 141
posted January 22, 2001 08:27 PM
Other than acceleration, what are some other benifits? Thanks for the info you've given so far.

Dirt Freak

Total posts: 219
posted January 23, 2001 11:13 AM
Limited 5, I don't see any real advantage to running them, we don't normally run them ourselves. I have a 406 with them only because I got the whole assembly for $500 and everything in the thing was new. Three people owned this and couldn't get the rods to clear with the longer stoke, I knew from my past that I could get this combination to work.........They are only a little lighter than say a stock rod and about 3 times the cost. I know a few people that run them in 350 motors because clearance isn't as much of a problem......light weight, cheap and will live long if you run a light weight flat top piston..........Myself, I run a heavy dome with around 12.5 to 1 compression, so these rods will have a life span around 20 shows.

Dirt Full Roller

Total posts: 37
posted January 25, 2001 11:22 PM
Don't waste your money. Aluminum rods have few, if any applications, in circle track. The main draw to them is the misconception that they're very light. To be strong enough, aluminum rods become so bulky, that their weight now rivals that of good lightweight steel rods. This bulk is also tough to clearance for in a stroker application. About the only benefit I see in aluminum rods is in a drag race car on nitrous because they tend to absorb damaging shock.

Dirt Newbie

Total posts: 1
posted January 26, 2001 12:35 AM
aluminum rod in 2" journal hold up very well up to 8000 rpm in c&a brand!we ran a set of 5.7" in a round track late model 331 c.i. for a whole season and won the championship afew seasons ago.we turned the motor 8200 on a 3/8 mile dirt at penton raceway alabama and scared people with my 180 degree headers (bumblebee).they are much stronger on the bottom end because the forging is the same one used for 2.1 rods bored smaller.the rotating big end is about as heavy as a steel rod but the reciprocating end that counts is much lighter.that and their shock absorber capability makes them rev like a motorcycle.keep temp 200 or less &dont run hot!


Back to the Archives