Author Topic: Pushrod length  (Read 954 times)

Offline moparmaniac59

  • Resident
  • *****
  • Posts: 3772
  • Drive it like ya stole it!
Pushrod length
« on: February 06, 2008 - 10:55:37 PM »
OK,
I'm trying not to beat a dead horse here!!  :horse: I've done a search on archived info for this subject, but still am a little fuzzy on the actual technique of setting pushrod length.  :dunno: I understand the principal that I want at least .010" preload on my lifter (it's  hydraulic) and no more than .050". I will be installing a different set of heads on my 440. How do I actually go about doing this task? I think I remember doing it with an adjustable pushrod, and using the readings from that to make up a set?? How bout it anybody?? Thanks!! I'd still be sitting in my garage scratching my head if it wasn't for the help I've gotten here! :2thumbs:

                                                      Matt B.
Matt




nivvy

  • Guest
Re: Pushrod length
« Reply #1 on: February 07, 2008 - 05:18:33 PM »
what type of rockers r u using???  use an adjustable pushrod checker and set the rockers on the #1 cylinder lets say... to recommended cam specs valve lash... alot of mopars is .26 to .28 range... and that is the length of the rod you wan but yu have to factor in what stylr pushrod you are using also...

I run a ball cup and set my cam to .016 on the intake and .018 on the exhaust.. I used a comp cams adjuster so I pull the adj. pushrod out after setting lash and that was the length i used... however no more than 3 threads can stick out the bootm of the adjustable rocker... adj. the push rod to wher 2-3 trads max are showing with the proper las settingof the cam.... each turn on the comp cam adj. pushrod is .050 so its easy to figure rod length... if this makes any sense to you ???
« Last Edit: February 07, 2008 - 05:26:32 PM by StRoKer »

Offline matt63

  • Sr. Member
  • ****
  • Posts: 1855
Re: Pushrod length
« Reply #2 on: February 07, 2008 - 06:06:42 PM »
If you've got roller tip rockers you have to make sure that roller tips are centered on the top of the valve stem.  They do roll back and forth across the top so you have to watch the travel.
Matt in Edmonton

'68 Valiant
'73 Cuda 340 4 speed (408) SOLD

Offline moparmaniac59

  • Resident
  • *****
  • Posts: 3772
  • Drive it like ya stole it!
Re: Pushrod length
« Reply #3 on: February 07, 2008 - 06:11:42 PM »
I was talking about stamped rockers (stock) with a 509 hydraulic cam and lifters.

                                        Matt B.
Matt

Offline matt63

  • Sr. Member
  • ****
  • Posts: 1855
Re: Pushrod length
« Reply #4 on: February 07, 2008 - 06:46:37 PM »
Unless there has been major milling or mods I would just use the stock length.  As far as the pre load goes I'm only guessing it won't be extremely accurate due to factory variances in deck height, rocker ratio, etc.  Lots of motors run fine like this.  Unless you want to custom cut each one individually I would just run the stock push rods or pony up for adjustable rockers if you're not happy with that scenario.  I think you can shim the rocker shafts but I don't know much about that option.  Some of the adjustable rockers aren't too expensive and probably not a lot more than a set of cut to length or adjustable push rods.
Matt in Edmonton

'68 Valiant
'73 Cuda 340 4 speed (408) SOLD

nivvy

  • Guest
Re: Pushrod length
« Reply #5 on: February 07, 2008 - 06:55:07 PM »
On the Indy 499 we shimmed the shafts and started having T&D rockers break.... but I think they were getting a little old for $1000 rockers  :2cents:

Offline dodge freak 2

  • Full Member
  • ***
  • Posts: 825
Re: Pushrod length
« Reply #6 on: February 07, 2008 - 10:36:42 PM »
E-bay can be a poor guys friend. But you need to wait and just go after the good deals. The buy it nows are sometimes the best but you need to be fast. If its been on more that a day, chances are if it was a great deal it be gone by then.

I went from stock rockers, to adjustable. Had a bit of trouble setting the pre-load at first. With the Hyd. after you set the pre-load, 20 mins later it be loose again. Until the oil pressure pumps them up again. Well dumb dumb me forgot which ones I already did and reset them again. Motor ran good at first but 10 mins later it lose compression in 1 or more cylinders. So its best to go in a straight line and not jump around setting the pre-load.

Anyhow, my motor picked up 300-400 more rpms by just having about .010 pre-load, so I was happy once again. Stock non-adjustable rockers stink.   

Offline Chryco Psycho

  • Administrator
  • C-C.com Guru
  • *****
  • Posts: 36620
  • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
Re: Pushrod length
« Reply #7 on: February 07, 2008 - 11:48:28 PM »
the adjustable lenght checking tool is under $20 from Comp cams , just buy it , you need to be sure you are on the base of the cam lobe , run it up to no lash & add .020

Challenger - You`ll wish You Hadn`t