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1.6 rockers on vortec heads

This is a discussion on 1.6 rockers on vortec heads within the Performance forums, part of the General Discussion category; Can anyone tell me if 1.6 ratio roller rockers will work on stock vortec heads without elongating the pushrod hole? ...

  1. #1
    Naturally aspirated! PSWired's Avatar
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    1.6 rockers on vortec heads


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    Can anyone tell me if 1.6 ratio roller rockers will work on stock vortec heads without elongating the pushrod hole? I'm thinking about installing some crane gold race self aligning rockers on my 383, but don't want to pull the manifold off to collect the metal from grinding the holes out. Here's a picture of my heads:



    If they have to be elongated, is there a way I can do it without pulling the intake manifold?
    1995 GMC Yukon

    -383 stroker engine, built 4L60E transmission, 2800 stall converter, 4.10 gears, Eaton Posi
    -16x8 AR Sliders with 285/76/16 Bridgestone Dueler A/T Revo tires
    -Stealth aftermarket sound system, alarm/remote start, Escalade cluster

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    Vortec HSR forsaken_one's Avatar
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    I 2nd this post, i was wondering the same thing, i have some comp cams magnum roller-tipped rockers waiting to go on something. I know that on my stock heads, i didnt have to enlongate the holes, but it was so close, it bothered me cause i thought it was gonna rub and get warped or at least loose HP.

    I wouldnt recommend cutting the holes longer with your manifold still on, its risky enough cutting it with the heads still attached.

    PSWired, are you going to get longer pushrods too?

    Kenny

  3. #3
    formerly rcfast
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    the 1.6 ratio are fine on a stock vortec...meaning no head work or cam or any other valve train mod...might have lift issues with a cam and the 1.6's

    98 silverado....Built 383
    Trying to do thing's a l31 "could never do"

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    Vortec HSR forsaken_one's Avatar
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    Please refresh my memory, What is the Max lift on a stock vortec head?

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    Naturally aspirated! PSWired's Avatar
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    Was not planning on new pushrods. The cam in there is pretty close to stock right now, the springs are 110lb units so they will be fine. I can look up the lift if I really have to, but I think I'll just order them and see how it goes.
    1995 GMC Yukon

    -383 stroker engine, built 4L60E transmission, 2800 stall converter, 4.10 gears, Eaton Posi
    -16x8 AR Sliders with 285/76/16 Bridgestone Dueler A/T Revo tires
    -Stealth aftermarket sound system, alarm/remote start, Escalade cluster

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    Original Gold Member 97Silverado's Avatar
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    Here's something new you might look into....



    http://www.cranecams.com/whatsnew/shaftmount.htm

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    Vortec HSR forsaken_one's Avatar
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    The reason i asked about the pushrods, was because, it is recommended by engine builders if you change the rocker arm ratio. Getting longer pushrods will help keep the rocker geometry the same. But i know it can be done without it, just wondering if you were going to do the extra step.

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    Original Gold Member 97Silverado's Avatar
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    Originally posted by forsaken_one
    Please refresh my memory, What is the Max lift on a stock vortec head?
    The only drawback to the head is that the stock valve springs can only attain around .425" valve lift Mostly due to the oversized guide and tall seal height. Machining the valve spring pockets for larger valve springs and reducing the seal height will allow for lifts into the .550 range.

  9. #9
    Vortec HSR forsaken_one's Avatar
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    You wouldnt happen to know if the vortec heads on my crate engine came modified or are they just stock?

  10. #10
    Vortec HSR forsaken_one's Avatar
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    The came that came in it has .435"in and .460" exhaust. I personally thought the max lift for the stock heads was higher than .425" though.

  11. #11
    Original Gold Member 97Silverado's Avatar
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    Originally posted by forsaken_one
    The came that came in it has .435"in and .460" exhaust. I personally thought the max lift for the stock heads was higher than .425" though.
    The factory Vortec heads use a light, single-wire valvespring with a damper that generates between 70 and 80 pounds of load on the seat. Because these heads are meant to work with a 1.5:1 rocker, their tall valve guides can only handle maximum valve lifts of around 0.420 inch. With a longer rocker arm ratio and the stock spring you run the risk of valve float. That's not to say it will happen but you are increasing the risk. Here is an example of the machine work that needs to be done to the valve seat to run stronger springs. You have to be very careful no to increase the depth of the valve seat or you run the risk of ruining the head.


  12. #12
    formerly rcfast
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    i have heard u can mill the seats down without removing the heads...97 did u do that yourself?

    98 silverado....Built 383
    Trying to do thing's a l31 "could never do"

  13. #13
    Naturally aspirated! PSWired's Avatar
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    I went ahead and ordered those rockers the other day, I'll post once I get them installed (or find out they don't work). Crane extruded aluminum gold race rockers, narrow body, self aligning, 1.6 ratio.
    1995 GMC Yukon

    -383 stroker engine, built 4L60E transmission, 2800 stall converter, 4.10 gears, Eaton Posi
    -16x8 AR Sliders with 285/76/16 Bridgestone Dueler A/T Revo tires
    -Stealth aftermarket sound system, alarm/remote start, Escalade cluster

  14. #14
    Original Gold Member 97Silverado's Avatar
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    Originally posted by rcfast
    i have heard u can mill the seats down without removing the heads...97 did u do that yourself?
    Naw, just a pic I had. I have the skills but I wished I had the tools to do that. And yeah, you could probably work the seats without pulling the heads but I personally wouldn't. Too big a chance that you can get something inside the engine.

  15. #15
    formerly rcfast
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    How much do you think it would cost to get the seats milled?

    98 silverado....Built 383
    Trying to do thing's a l31 "could never do"

  16. #16
    Original Gold Member 97Silverado's Avatar
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    Originally posted by rcfast
    How much do you think it would cost to get the seats milled?
    No clue, you would have to talk to your local machine shop. I can't see it being that much though.


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