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Old 12-02-2012, 02:40 PM
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roller rockers on vortec heads

Hey guys ? For you I was wondering if I have to run speical rockers on vortecs and if you could give some part numberd would be appreciated

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Old 12-02-2012, 03:40 PM
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roller rockers on vortec heads

The self aligning rockers are used with the center bolt valve covers. If using the old style valve covers use full roller rockers, guide plates, and hardened pushrods.
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Old 12-02-2012, 04:39 PM
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I used Scorpion SCP 1073BL full roller rocker arms.
They are 1.5:1 ratio, narrow body, self aligning, no guide plates. I used ARP 134-7301 3/8"-24 screw in rocker studs. My Comp Cams beehive valve springs were set up at 1.750" at 144 lb. closed and 330 at .500" valve lift.

Comp Cams 1015-16 (1.5:1) full roller rockers have the same specifications.

Full roller rocker arms are only necessary if your valve springs have pressure approaching 350 lb. open or you risk burning up rocker pivot balls.

If you need new rocker arms anyway, and have valve springs with less than 330 lb. open pressure, Comp Cams roller tip rockers will fit Vortec heads with center bolt valve covers. Comp Cams 1417-16, 1.52:1 ratio or Comp Cams 1418-16, 1.6:1 ratio. They should be used with less than 325 lb. open pressure.
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Old 12-02-2012, 05:25 PM
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You didn't say what pn Vortecs you've got, or exactly what rpm you plan on turning, roller or flat tappet cam, or how much you want to spend?
I'm guessing that you have stock springs, and studs(3/8" w/no guide plates), and center bolt valve covers?
If I'm not mistaken, you have a stock bottom end on a 400 sbc, or at least you did on a previous post. If it has stock rods w/stock bolts I wouldn't turn it over 5500rpm IMO. If you have stock pistons you'll probally have problems with too much compression,
Stock heads had around 76cc combustion chambers. Vortecs have around 64cc if I'm not mistaken. Installing vortecs would raise the compression ratio at least one full point if not more. If the stock engine had 8.75:1 CR w/76cc heads, it would increase to at least 9.75:1 with vortecs and detonate on pump gas if everything else remained stock IMO. I know for a fact that no 400 sbc came stock with vortec heads.
If I'm not mistaken you said you had a Comp XE256 cam in mind on a previous post. The early closing intake valve would cause the dynamic compression to be around 8.5:1, too much for iron, or aluminum, heads on pump gas IMO. I'm guessing 0.25" in the hole, stock bore, and an 18cc dish volume. May be more like 12cc (someone that knows better is welcome to chime in) which would make things even worse.
You really need to reconsider your use of stock pistons if thats what they are?
If you have stock springs you don't want to run a roller cam(not enough pressure to controll roller lifters). If the heads don't have the stock valve guides machined for more than stock valve lift, you don't need 1.6:1 roller rockers, and are limited to about 0.450" valve lift.( I'm guessing thats why you picked the 256 cam?)
In my opinion with that small of a cam you don't need roller rockers. Stock type guided rockers would be fine.IMO
Others have tried to tell you about the excesive compression. You really need to see that they are trying to help you from blowing up your 1st engine, before you can even get it broke-in, or at least read up on it for yourself. Here is an excelent article IMO on dynamic compression, and a compression calculator you can download that can help you make an informed decision.
Dynamic CR
stock type rockers summit pn NAL-12495490
I know others will disagree on the roller tip w/ball type fulcrum, but
I've had good results with these style of Comp rockers for over 15 years. Summit pn CCA-RP1417-16, but like I said the stock type would work fine.
I can't say what full roller rocker would work with centerbolt valve covers, sorry.FWIW.
Edit: I took so long to type I see that others have beat me to it. I started about 2 hours ago.
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Old 12-03-2012, 05:33 AM
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The first thing you should do is replace the stock pressed-in rocker studs with ARP 134-7301 rocker studs, no matter what valve springs or rocker arms you use. They are preferred even with stock equipment.
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