Rocker question

[flyinlow]

Anyone using Comp Cam Pro Magnum roller tip rockers? (1621-16)   Long term street use?

[BSB67]

Yes.  Mine are older and I think they have gone through a few upgrades since then.  I see that they are now rated for 850 lbs. Do these have actual rollers on the shaft or are they bushed?  Looks like both are available.  Mine had neither so I sent them to RAS and had them bushed.  I'm using them with a solid roller cam and they are working fine.  220/520 seat/over-the nose, and regularly see 6500, and have been 7000.  I like them and would buy them again.

You are looking at higher end rockers, and HS is the go to standard that a million people have had success with.  You certainly cannot go wrong with those as a choice as well, but this is why I chose the Comps: 1) I prefer to not have rollers on the shaft, 2) they are not aluminum, 3) the tip lines up better (actually perfect) when used on factory, Eddy and Stealth heads, 4) they provide oiling to the tip, 5) they provide positive/direct oiling to the pushrod.

[flyinlow]

Thanks!

Yea these are bushed with a roller tip. I too am concerned with  possible long term fatigue  problems with aluminum rockers, so I was looking at Crane ductile iron or the Comp cam steel ones. I have a mild Lunati hydraulic  cam with about 300lbs. of valve spring pressure open. I had been running stock rockers on an Eddy head engine for years (about 40k miles) when driving home the rocker shaft broke between #6 and #8 cylinders. It looked like the rear bolt loosened and the shaft bent and broke at the  #4 retainer bolt.  The cam pushed two lifters out of their bores and the engine lost oil pressure. I shut it off and towed it home. Outside of the broken rocker shaft  their dose not appear to be any damage.    I thought about replacing it with an other stock rocker shaft, but thought the upgrade would be better.

[cdr]

keep in mind you will need custom made push rods.

[c00nhunterjoe]

We have the comp rockers on the 63 dodge. The bushed version. Been on the 426 for 2 race season now. Will have to check the paperwork for spring pressure but its a legit 13:1 superstock max wedge engine over 600 horse spinning over 7500. No issues with the rockers. Good quality product.

[flyinlow]

The comps are about $200 more than the Cranes,   but they come with new rocker shafts.  Comp cam says they use standard C.M. pushrods with ball ends vs. the Crane's that need pushrods with cups at one end.

[c00nhunterjoe]

I personally feel the comps are a superior product. And yes, ball on ball.

[flyinlow]

What length pushrods?  Looking at Comp cam CM 5/16"  with ,080 wall thickness.

[cdr]

you will need a push rod that is made for measuring with the rockers installed & then order the length you need.

[flyinlow]

I talked to a Comp Cams tech guy too verify that these rockers could be expected to go 100k. miles+ in a street engine with a mild cam and said they would properly set up.    Ordered a set.

So I should order a pushrod measuring tool also. If I understand this you bolt the rockers on. Set the engine to #1 compression TDC. Set the rocker adjuster to have about 2-3 treads showing. Measure the #1 cylinder length without compressing the lifter adjuster. Then you want a pushrod about .030-.050 longer for proper lifter preload?

Once you install the correct pushrod can you preset the adjusters?  With the cam lobe on the base circle adjust out the lash then tighten 1 additional turn and lock the adjuster?

[c00nhunterjoe]

No, that will be incorrect. Tdc and measuring number 1 will give you the wrong data. If you set it on tdc, then you can use the intake on cyl 2 or the exhaust of cyl 8 for your measurement. And 1/2 turn for preload should be good.

Edit- that is assuming the cam is mild. The safest way i have always done valves is the intake closing, exhaust opening method.

[flyinlow]

Edit- that is assuming the cam is mild. The safest way i have always done valves is the intake closing, exhaust opening method.

Not sure I follow you? 

[c00nhunterjoe]

Pick a cylinder, no 1 for arguements sake. Rotate the engine and, in this case, watch the lifters. When the exhaust lifter just starts to open, you will know that the intake is on base circle so you can measure your pushrod length there.