In my dart I have a 71 360 Weiand Stealth Intake Manifolds 8022 Doug Thorley 15/8 headers a1 3500 stall conver manual vb Holley 650dp Will be switching automatic To 4 speed 81/4 not sure if your ratio no power steering no power brakes al6 msd I have a set of j heads gone through and shop down 20,000 but not on the motor yet




My question is I have read about this cam on small block and some guys have used adjustable rocker arms and some haven't. I do have a set of 273 rockers Why are some guys not using adjustable rocker arms On the comp website it says it's recommended


Thanks guys Mopar or no car

In some apps it is desireable to set the preload down a certain amt from the lifter snap ring. Which ain't answering your Q but here is a BTT for ya.

Because adjustable rockers are not NEEDED. It's one of those turd polishing things on a hydraulic cam that 99% of the time is unnecessary.

I'm sure Comp recommends a bunch of other stuff too, it's called add on sales.

Ive used that cam on a low buck rebuild with oem rockers, not sure if it was preload relate but the lifters would tick for a second on cold start and if it was related it never was an issue with the oem rockers, I think im at 36k on the old truck now.

If you google it or look on fabo its a pretty common cam for mild use.

So should I run a stock rockers or the 273 adjustable ???

Either set up should work as long as you get proper preload using stock rockers.

Adjustable make things easier to set preload individually.

If you have to buy push rods, it's nothing more than the cost of rockers or using what you have.

I would mockup with your regular non adjustables & see what the preload is. Knowledge is power. then you will be in an informed position to see if you need the 273 setup. Odds are in a mild app with any preload you will be fine.

Here's comes the turd polishing.

Before you get too worked up about preload, go look at the preload specs in the FSM. It's pretty much "as long at there is some and it doesn't bottom out you are good".

On that mild a cam go with the FSM specs, which means you are most likely good to go.

Maybe apples to oranges, but I am using that cam on my 440 with Edelbrock heads and intake with stock rockers and no issues based on the Moparts recommendations. My motor is mild and it saved me $$$.

This is not too big a cam for stock rockers. As a matter of fact they might extend the usable rpm range because their moment of inertia is smaller than a rocker with an adjuster or with a beefier body. Dulcich mentioned this in an article, where his LA motor lost rpm when they substituted Comp Pro something rockers for the stockers with no other changes.

IMHO the main reason Comp or Edelbrock or whoever says to use adjustable rockers is to protect them from stupid customers. If you understand that pushrod length matters and that preload is needed in a hydraulic lifter, but it can vary quite a bit, you are smarter than their target audience.

R.

The first 340 I ever built I had a comp hi energy 268 hydraulic in it with comp lifters, with a decked block and milled heads - nothing fancy, just enough to make 'em straight and flat, and stock rockers. That motor with stock rockers would break up at 4500 rpm due to the lifters pumping up and the valves not closing. I added 273 rockers and it revved to 6000 no problem. If you've decked the block or milled the heads I'd run the 273 rockers. Either that or read up on shimming the rocker shafts if you run into the issue I described.

Stock non adjustable rockers will work just as long as the push rods are the right length.

I would use the adjustable 273 rockers, they are stronger and will allow you set the preload exactly where you want it. Easier than getting the right push rods especially if all 16 push rods at the same length don't work for all 16 with non adjustable rockers. What if one push rod needs to be longer or shorter than the rest when you check pre load? Then adjustable rockers come in handy.

As mentioned, with a mild cam like this, you really only need to have the correct lifter pre-load, which can vary quite a bit with stock type lifters, from about 0.020" to 0.080" (some lifters can take a bit more depends on brand.) Usually, I like to get custom length pushrods that give 0.040" lifter pre-load.

Here is what I use when deciding to not use the stock rocker arms:
Higher valve spring pressures can push the pushrods through the stock rocker arms. So, when going over 0.500" lift with stiff valve springs, it is a "good idea" to upgrade the rocker arms. I quoted "good idea" because everyone is going to post their 292/0.509" cam works fine with stock rocker arms. Alot depends on the valve springs used (seat pressure and spring rate), and how aggressive the cam lobe profile is.

.500" is pretty much my dividing line between farting about and being serious.

It only takes one pushrod through an old oem rocker at a really less than optimal time(where it kicks a lifter out and now you have 2 psi oil pressure to try and limp it home) and location for you to question when you would ever use them again in a "high performance" application.

The XE series of cams have much faster ramps than the oem cams the rockers designed for.
If you have access to a new set of the old MP HD stamped rockers that's a different situation than using a set of 30 year old stockers with an unknown history.

If I had some 273 rockers on hand, I know what I'd use(but then, I've already had the pleasure of putting a pushrod through a rocker with my old school .480 lift cam, at midnight, when I'm 20 miles from home and the oil pressure gauge is barely up off the "0" peg).

As mentioned in another thread the "MP HD rockers" are nothing more than later model OEM rockers.

As with ANY job, you replace wore out stuff if needed.

The j heads are getting 2.02 in them and bring cut .30 that should help with the preload right ???

Factor in your head gasket thickness vs what oem was.

I've seen many NHRA SB Mopar stockers push the pushrods through the stock stamp steel rocker arms at the races, both OEM and the mopar H.D. stamp steel rockers That was before NHRA allowed adjustable rocker ars, no NHRA Mopar stocker racers use stock rocker arms now
Use the adjustable 273 rockers now with the proper length pushrods for your lifters instead of later after breaking three or four stock type rocker arms
Do it right once now instead of fixing it later

I think comp has made all their hyd. Stuff on the same base circle for all makes to cut costs. Most likely smaller than factory Mopar. Last year I tried to order a cam based on the old card from a previous build, they told me the dash 3 suffix had changed to dash5. Why?,I said. Reply: that base circle is no longer used.