long VS short rods

[ek9r]

i was wondering about how long, or short my rods should be while running 12.5:1 pistons in a b18c5 using jun 3 cams. I was reading an article from turbo mag online, they say-
longer rods= slower reving engine w/ long duration cams
shorter rods= higher reving engine w/ shorter duration cams

now they got me thinkin that if i am running the long duration of the jun 3 cams, that i would want to go with a longer rod setup. Is this even possible to do considering piston to valve clearance? Hope someone can give me some advice.
thanks in advance!

 

[phunky.buddha]

Longer rods = more dwell time and more progressive piston acceleration in and out of TDC and BDC, not slower revving... but the cam recommendation is correct. Just run your stock rod length setup- if you don't, you start getting into custom rods and totally custom pistons. I do like my long rod setup though!



You can go with longer rods if you move the wrist pins up in your pistons, and that wouldn't affect your valve to piston clearance. On the other hand, lots of people have excellent results with Jun 3 cams on stock stroke geometry setups.

 

[ek9r]

i really feel that if i optimize that "longer dwell time" (allowing more air and fuel to enter the combustion chamber) that i would see better results and pull out max potential of the long duration of the jun 3 cams. What do you suggest i do. How do i know how long of a rod to go with, if i move the pin up higher in the pistons? will i have to modify the block at all due to the increased angle of the longer rods?
thanks John

 

[JDMilan]

if your trying to bust low low et's going NA then you might consider the minimal gains. I say stick with your current rod length, upgrade to a good aftermarket unit, if you are rebuilding, custom rods, cranks, pistons are for the big boys with lots of cashish from sponsors..

 

[phunky.buddha]

Your rod angle actually goes down, not up if you get longer rods- so you don't have to modify your block unless you make the rods MUCH longer than your stock ones.