Smith Bros adjustable pushrods....

[b5blue]

  I'm getting ready to order these, any suggestions or recommendations? They asked what diameter and length I wanted? I've got a fairly stock rebuild 440 with a Resto Road Runner cam from Mopar Performance with the recommended valve springs and bone stock 346 heads. I may switch to Eddy heads later (much later) but am doing this to clear up some lifter slop from the valvetrain. (I reused my valves and had a 3 angle done to the heads along with a surfacing cut.)
  Anyone got the "stock spec." for 440 pushrods?     

[firefighter3931]

Neil, what rockers are you using ; stock or adjustable ? Mechanical or hydraulic cam ? Need more info ! 

The best way to determine the correct length is to measure using a "checking pushrod" which is adjustable....then adjust the desired length based on lash or pre-load requirements. 


Ron

[FLG]

Neil, what rockers are you using ; stock or adjustable ? Mechanical or hydraulic cam ? Need more info ! 

The best way to determine the correct length is to measure using a "checking pushrod" which is adjustable....then adjust the desired length based on lash or pre-load requirements. 


Ron

Neal,

If your using stock rocker arms ive got a set of smith bros pushrods that might work for you...just need to know the length.

[b5blue]

  Thanks guys, I installed new HD Mopar stamped rockers, it was a package deal from Mancini Racing. It included rocker shafts and their brand pushrods for an RB engine. These should be 3/8 dia. @ 9.31" length pushrods but the rep. at Smith Bros said they have seen considerable variance in pushrods from slack tolerances. I know it's close to correct as is, the tapping lightens up as the engine warms up but on some never disappears completely.
  This subject is covered in my B/RB Mopar Performance engine book and ideally I would have ordered cut to length pushrods and an adjustable checker but with my re-launch schedule so tight (My son needed my beater for going to USF ASAP!) I just kept my fingers crossed. (And lost.) The plan was to just install Crane 1.5 Ductile Iron adjustable rockers and ball/cup pushrods later, but they are out of production for many years now just my rotten luck!
  My cam is hydraulic, Mopar P4452783 268/284 duration w 46* overlap, 115* centerline, .450/.458 lift, springs are P3690933 (Cam chosen to match six pack spec. without the lower cam lobe taper and 3 bolts as I had already bought a new 1 bolt timing gear and chain set earlier.) 
  Mopar part # P4286810 Adjustable RB pushrod is what I'm duplicating I assume, it's not available ether. I can't find a "spec." for them so the 3/8 @ 9.31 would be the center of adjustment range I'm guessing.

[firefighter3931]

  Thanks guys, I installed new HD Mopar stamped rockers, it was a package deal from Mancini Racing. It included rocker shafts and their brand pushrods for an RB engine. These should be 3/8 dia. @ 9.31" length pushrods but the rep. at Smith Bros said they have seen considerable variance in pushrods from slack tolerances. I know it's close to correct as is, the tapping lightens up as the engine warms up but on some never disappears completely.
  This subject is covered in my B/RB Mopar Performance engine book and ideally I would have ordered cut to length pushrods and an adjustable checker but with my re-launch schedule so tight (My son needed my beater for going to USF ASAP!) I just kept my fingers crossed. (And lost.) The plan was to just install Crane 1.5 Ductile Iron adjustable rockers and ball/cup pushrods later, but they are out of production for many years now just my rotten luck!
  My cam is hydraulic, Mopar P4452783 268/284 duration w 46* overlap, 115* centerline, .450/.458 lift, springs are P3690933 (Cam chosen to match six pack spec. without the lower cam lobe taper and 3 bolts as I had already bought a new 1 bolt timing gear and chain set earlier.) 
  Mopar part # P4286810 Adjustable RB pushrod is what I'm duplicating I assume, it's not available ether. I can't find a "spec." for them so the 3/8 @ 9.31 would be the center of adjustment range I'm guessing.

With a non adjustable rocker arm you simply measure using a checking pushrod with the cam on the base circle. Ideally you want there to be zero play/vertical movement of the pushrod....then add in extra length for preload.

It might be worthwhile to check the amount of preload you currently have with the existing parts then add in an extra .020 when ordering new pushrods.



Ron

[b5blue]

You get my problem Ron.
  If cam's lift height ultimately are and can only be the same due to the fact they must fit through the cam bearings inner diameter, the true measure of height is the difference between base and peak. (Like measuring how high mountains are from the bottom of a valley.)
  I'm assuming the 9.31 pushrod was used in all production HP 440's and they used the cam I have. (This stuff was all part of why I got the cam I did.) Had I installed all new heads I "should" have been right in spec. and all the hydraulic lifters would be quiet.   
  The only way to really know optimum is a real world check as you stated, thanks!