Adjustable rockers necessary??

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Lil Demon

Lil Demon

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Hi, I am getting ready to build up my 340 with X heads. I will be using the XE268 from Comp. My machinist insists that I use adjustable rockers. After shopping around I don't really feel like dropping that kind of cash for them. Are they really necessary? Or will a new Mopar rocker set be sufficient? I imagine he is concerned with uniformity in lifter preload. Can that be obtained with non-adjustable rockers? Any advise would be appreciated.
 
Im running hyd on mine, The adjustable will work better but if your a street driver I doubt you can tell the diffrence other than the solid lifter will be noiser.
 
Less deflection on a solid adjustable rocker over the stamped stock style. You will get a true-er lift. You may or may not notice the difference, but I believe that to be the main difference. If you are running solid lifters, the adjustable are probably preferred to set your lash. With Hydraulic the adjustment is really less of a factor.
 
Ok, thanks, Yeah I will be going hydraulic too, but my machinist still insisted on adjustable rockers. Anyone else with experience or insight on this?
 
Yes, they are necessary to get full potential of a high performance cam, IMO. Are the necessary to simply run? No.
 
I'm always all for making it better. Any suggestions on which ones to buy, decently priced ones preferably.
 
i agree with rrr, that said saetun has the same cam in his teener and it runs great.
 
IMO factory 273 adjustable rockers would work fine... anything better is overkill. Stock stamped rockers would still work OK as well since your cam is a street hydraulic, not sure why your machinist is so adamant about it
 
Thanks for the great responses guys! Are the factory 273 rockers still available? and where??
 
Probably because something has been milled. When you machine the heads or block, the pushrods are now effectively longer and depress the lifter plunger further down with more preload. Without some sort of adjustment, this cannot be corrected.

IMO, the factory 273 rockers, when you change out the stock adjusters for high quality ones, are some of the best pieces available for the small block, barring something from perhaps Crane, Hughes, or Harland Sharp. IMO, they are that good.
 
RustyRatRod said:
Probably because something has been milled. When you machine the heads or block, the pushrods are now effectively longer and depress the lifter plunger further down with more preload. Without some sort of adjustment, this cannot be corrected.
Click to expand...


Great point 3xR
 
I have a set that I would let go for $150 plus the ride. :thumblef: Shoot me a PM if interested.
 
Pulled them off of my great running motor recently.
 

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Great, so where can I get those higher quality adjusters to go with these rockers pictured?
 
Summit. Also, you'll need to run a tap through all the rocker adjuster holes to get rid of the self locking threads. The adjusters have lock nuts on them. Plus, you will have to spot face the area where the lock nut will tighten down so it has a flat area to tighten against. VERY simple procedure you can do yourself or have a machine shop do.
 
.. if the valve seats are worn to different depths adjustable rockers can be one solution to extensive head work.
 
Lil Demon said:
Hi, I am getting ready to build up my 340 with X heads. I will be using the XE268 from Comp. My machinist insists that I use adjustable rockers. After shopping around I don't really feel like dropping that kind of cash for them. Are they really necessary? Or will a new Mopar rocker set be sufficient? I imagine he is concerned with uniformity in lifter preload. Can that be obtained with non-adjustable rockers? Any advise would be appreciated.
Click to expand...


Absolutely go with a set of 273 Adjustable Rockers.

The deflection in the stamped steel units can be up to .005"
under a high-load rate.

In normal driving, you won't be able to tell the difference, but
in upper RPM's there is a noticeable HP edge, as there is less friction as well.

The Comp Cams XE268 has a .477" Lift and 268*/280* Duration, so clearance
between the Valve Spring Retainer and under-side of the Rocker Arm should be
adequate.

If you're going with the Com Cam #901 Valve Springs {101 lbs. @ 1.625" and 242 lbs. @ 1.250"}
there again should be adequate clearance.
 
You may have it right Rob; Summit says the '802s are the right ones for 64-69 273s, (did they still exist in '69?), but we all know they sometimes have errors...
 
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