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rocker arm help

3K views 24 replies 8 participants last post by  makennoise 
#1 ·
My rockers are hitting my retainers will lash caps and longer push rods help or is there something else wrong here Auto part Machine tool


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#2 ·
Longer pushrod and lash cap may work...but some other questions first.

Are the rockers clearance cut on the underside to clear that diameter retainer?? What brand are they??

Is your rocker geometry set up correctly??, as it doesn't appear to be because you have an awful wide sweep pattern.

How to do geometry correctly : http://api.viglink.com/api/click?fo...www.youtube.com/watch?v=o5is...m-upload_owner

It is more important for sweep pattern to be narrow than it is to be centered on the stem.

What method did you use to determine your pushrod length??
 
#3 ·
Ericnova72 Yes the rockers are cleance cut for the diameter of the springs they are PBM roller rockers as far as sweep its a .600 lift can so I thought that it was good (prob wrong) they where put in bye some one else was going to try to use them switched heads from procomp to darts and I think both where the same length valve just different spring diameter
 
#4 ·
The width of your sweep pattern on the tip indicates to me the pushrods are too short right now. just getting the correct length longer pushrod in there may give you the retainer clearance you need, with no need for lash caps.

Watch the instruction vid I posted and figure out your correct pushrod length and see how that compares to the pushrods you have now.
 
#7 · (Edited)
I just had this problem with 1.8" stud length. After setting pushrod length, I found there to be not enough poly lock thread engagement. I opted to replace them with ARP 334-7203 studs @ 2.1" long.
ARP also make a stud ARP 235-7203 @ 2.00". These are 7/16" studs. Haven't researched 3/8" studs.
You could put a hardened washer under the stud if they are just little too short.
My 1.8" studs weren't even long enough to check pushrod length after watching Straub's mid-lift video.
 
#8 ·
One other thing to be aware of with stud mount rocker arms.
Usually as longer valves and pushrods are added to engine combinations the rocker arm trunion will ride up higher than the shank of the rocker stud. The shank portion of the stud is a larger diameter than the threaded portion and is intended to let the rocker be more stable on the stud.
Unfortunately I have not been able to find any studs that lengthen the shank portion of the stud.
To remedy or band aid this, adding hardened washers under the stud will raise the shank portion higher up into the rocker trunion. This brings up another situation of the bottom portion of the stud having less threads screwed into the head.
Check out the ARP web sight to figure out which rocker stud will work best for you.
This is where shaft mount rocker arms become a great asset.
Best of success with your build.
 
#16 ·
In my mind, a 0.550" longer pushrod does not seem appropriate, but maybe I'm missing something.

You will also need valve locks that accept lash caps if you go that route. If your springs are more than 500lbs over the nose or this is an endurance engine(boat, oval or road racing,etc.) I would suggest going to steel rocker arms from Comp.
 
#18 ·
8.700" is way too long for any combination of currently available 23° and a standard deck height block.....I would expect to see 8.250" max.

I'd say go back through the method again, it seems you must have missed something, like dialing the rocker nut down the correct amount after doing the calculation from the 90° valvestem to rocker pivot alignment. One nut rotation on a 7/16"-20 thread stud is .050" distance
 
#22 ·
Still seems way too long, I've never seen anything that long in a 23°head, even with shaft rockers....and especially since you only have +.100 longer valves.

Are you using the Straub method??

if you note his video, the Big Block intake pushrod he was measuring was 8.750"...that's a common BBC length !!!, nothing standard deck SBCand 23° head should even come close to that.

I've got to believe you are misinterpreting a step somewhere. Just judging off the sweep pattern in your pictures, the current pushrod is only .050" to .075"or so short in my experience.
 
#25 ·
Jumpin jim was thinking same thing block calls for +.300 lifters and I thought that was what was in motor before cause they fit with plenty of room and every thing that I have found says that the seat height between the .300 and regular roller says that its the same seat height
 
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