Author Topic: Push Rod Length For Adjustable Rockers  (Read 789 times)

Offline AMXguy

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Push Rod Length For Adjustable Rockers
« on: March 23, 2010 - 07:43:51 PM »
On My Crane Ductile rockers when adjusted I have no threads showing on the bottom of the rocker, they're flush. there is plenty sticking out and everything looks like it should work fine but since I'm at the limit of my adjustment I thought I'd ask. how do you detemine proper length on adjustable rockers? or is it that important?
1970 R/T SE Challenger
 1970 Superbee
 1969 S code Mach 1
 1967  GTO




Offline TROUBLE987

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Re: Push Rod Length For Adjustable Rockers
« Reply #1 on: March 23, 2010 - 08:01:57 PM »
did you have the heads deck alot? And are you saying you have back the set screw all the way out and when you look up under the rocker your not seeing any threads? if so make sure the rocker is not hitting the pushrod cup make sure it stays on the rocker tip..and if you did deck the heads a lot,they may be a little long and there is a few ways to fix that either check and see if the offer a shorter push rod or call and get some cut to fit ones and make sure you get the pushrod that screws out to mesure the lenth you need

Offline AMXguy

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Re: Push Rod Length For Adjustable Rockers
« Reply #2 on: March 23, 2010 - 08:43:00 PM »
Where it's at is the threads are flush with the bottom of the rocker and then the ball sticks out another 1/4 or so. I'd say there's about 1/8' clearance between the cup on the push rod and the bottom of the rocker. I don't see any clearance issue but I'm not sure if the angle of the dangle is anything to worry about or how to check it.

 Yes I've been decked and the heads milled but I bought a cometic gasket set which has me back to stock height  so I should be standard there.
1970 R/T SE Challenger
 1970 Superbee
 1969 S code Mach 1
 1967  GTO

Offline TROUBLE987

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Re: Push Rod Length For Adjustable Rockers
« Reply #3 on: March 23, 2010 - 08:47:55 PM »
do they look like this kinda at a bad angle?

Offline 71chally416

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Re: Push Rod Length For Adjustable Rockers
« Reply #4 on: March 23, 2010 - 08:59:51 PM »
You can always space the shafts up with shims.

http://chucker54.stores.yahoo.net/rocshafshim1.html
Once we had Ronald Reagan, Bob Hope & Johnny Cash. Now we have Obama, No Hope and No Cash!

Offline Changin Gears

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Re: Push Rod Length For Adjustable Rockers
« Reply #5 on: March 23, 2010 - 09:01:44 PM »
What's the clearance on a fully open valve?

No threads showing is not ideal, but is probably OK.  If you are really concerned you can fabricate some shims to go under the raocker shafts (about .020"-.030").


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Offline TROUBLE987

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Re: Push Rod Length For Adjustable Rockers
« Reply #6 on: March 23, 2010 - 09:07:24 PM »
What's the clearance on a fully open valve?

No threads showing is not ideal, but is probably OK.  If you are really concerned you can fabricate some shims to go under the raocker shafts (about .020"-.030").
Dang it you two beat me to it..lol..i was waiting on him to reply but yea thats what i did i went with the .30 on mine..and it fixed it

Offline Strawdawg

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Re: Push Rod Length For Adjustable Rockers
« Reply #7 on: March 23, 2010 - 09:13:18 PM »
Typically, no more than one thread showing is pretty much ideal.  Two showing is about as much as one should go.

Sounds like yours should be okay to me...check the geometry across the other end and see if the movement across the stem is pretty well centered.

Offline AMXguy

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Re: Push Rod Length For Adjustable Rockers
« Reply #8 on: March 23, 2010 - 09:50:19 PM »
Thanks I'll check it out.  I think the geometry looks pretty good but I'm not sure, after I get them all adjusted I'll turn it over a couple times and see. my main concern was being at the begining of the adjustment I thought it might mean something.
1970 R/T SE Challenger
 1970 Superbee
 1969 S code Mach 1
 1967  GTO

Offline TROUBLE987

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Re: Push Rod Length For Adjustable Rockers
« Reply #9 on: March 23, 2010 - 10:23:32 PM »
no as long as your not hitting then its fine i had cut my heads a good bit and mine pushrods would bump the rocker but i shim the shafts and all was good,i would let it be

Offline Strawdawg

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Re: Push Rod Length For Adjustable Rockers
« Reply #10 on: March 24, 2010 - 12:06:27 AM »
Thanks I'll check it out.  I think the geometry looks pretty good but I'm not sure, after I get them all adjusted I'll turn it over a couple times and see. my main concern was being at the begining of the adjustment I thought it might mean something.

May have to wait til it is running and lifters are pumped up....good time to reset the preload and see where you are :)