I currently have a 408 in shorty dragster. I’m gonna build a 18 degree headed motor this winter. I have been told to put 5.85 rods in it instead of the 6 inch I have now. Some say it will run better. Do any of you small block guys have any input on this? It’s 3.75 stroke 4.185 bore. Thanks in advance.

I would run 6 inch rods. I have 6 inch rods in my 3.875 stroke 18 degree motor.

Maybe if your supercharged or running a lot of nitrous and need to move the ring pack lower.

Like bc Malibu said,if you need to move top ring down for nitrous, go with 5.85 rods. Otherwise stick with six inch rods

Stop worrying about rod length and worry about ring package. Get that sorted out and connect the piston to the crank. Rod length is WAY overrated.

quote:

Originally posted by 66belair:
I currently have a 408 in shorty dragster. I’m gonna build a 18 degree headed motor this winter. I have been told to put 5.85 rods in it instead of the 6 inch I have now. Some say it will run better. Do any of you small block guys have any input on this? It’s 3.75 stroke 4.185 bore. Thanks in advance.

Depends on cam and induction etc, etc. But hypothetically speaking lets say you have one 5.85 rod engine, one 6.00 rod engine. And the 5.85 rod engine out runs the 6.00 rod engine. It'll be for a couple reasons 1. The torque converter multiplies more torque below stall due to the broad torque curve of the short rod engine. 2. The broad torque short rod is advantageous in comparison to a higher average torque long rod all things equal,,, gear (converter slip), converter stall (rpm).

I run 6" rods in my 4" stroke 15 degree sbc

Originally posted by Coloradoracer:
Stop worrying about rod length and worry about ring package. Get that sorted out and connect the piston to the crank.

quote:

Rod length is WAY overrated.

That's not what she said....
bada bump

goob- depends on your pinion angle, really....

quote:

Originally posted by Coloradoracer:
Stop worrying about rod length and worry about ring package. Get that sorted out and connect the piston to the crank. Rod length is WAY overrated.

Bingo!!!

I ran 5.850's in my 18* and 15* 399" motor. So many considerations went into that decision, but primarily the ring package.