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Thread: sbc rockers rubbing on springs

  1. #1
    Senior Member EXPERT BUILDER
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    sbc rockers rubbing on springs

    My sbc, with dart iron eagle 215 platinums,manley 1.550 springs and tit. retainers, are rubbing a groove in my scorpion 1.6 7/16 rockers which are cut for 1.630 springs .Only two rockers don't have a mark on them and some have a deeper groove then others.I had a set of Jegs rockers,which are cut for 1.560 and they also had grooves in them.My question is should I grind the grooves out or???????????????

  2. #2
    Member JUNIOR BUILDER
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    The last engine we were assembling with Dart Iron Eagle platinum 215 cc heads had a similiar problem. We had to use Crane off-set rocker arms and we cut the guide plates (compcams) and ground-fit then welded back up. We also offset milled the slots in the guide plates and used 3/8" push rods. The problem is the push-rod centerline and the casting are too tight. Without the offset rocker arms, just moving the push rod with adjustable guide plates puts the roller tip of the rocker arm off the center of the stem end of the valve. This problem only occurs with the intakes. Our exhausts were ok. Correcting the problem is a time consuming job, but once its done properly, you shouldn't have valve train issues.

  3. #3
    Senior Member EXPERT BUILDER
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    Both intakes and exhausts rub.I've been told to buy a set of crowers or grind the ones I have or leave them alone.What do you think?

  4. #4
    Senior Member RACING JUNKIE
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    Unfortunately, you got what you paid for.

    Scorpions and Harland Sharp rockers are meant for a mild upgrade.

    They often hit most of the nicer springs/retainers.

    You could grind them, but then in doing that you're removing strength at the critical point.

    The right way to do it would be to put them on RJ and buy a set of crowers or crane golds.

  5. #5
    Senior Member EXPERT BUILDER
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    If the retainer does not fit tight in the spring wouldn't the spring move and could this cause a clearance problem,henc cutting a grove on the rocker arm?

  6. #6
    Senior Member DYNO OPERATOR
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    A buddy of mine had that problem on his 408 sbc. He had Comp Red rockers on it. We went to a set of Harland Sharps. They have a much larger cut out for spring clearance. I had the same problem on my 408 w/ Comp HItech stainless rockers. (not exactly cheap) I went to a slightly longer pushrod that what was required to gain the extra clearance...

  7. #7

    sbc rockers rubbing on springs.

    The best information I can give is to refer you to Jim Miller Engineering or "Mid-Lift" geometry. The tech pages explains in detail the relationship of rocker arm geometry and push rod angle. Before you spend anymore money or grind your rockers, visit this sight. It seems to me that the rocker is to far down on the stud reducing your clearance. The person who suggested push rod lenght, is on the right track. The springs not fitting tight in the retainers could also be a contributing factor. The sight also addresses the problem of locating the rocker properly on the valve. This is a common problem with stud mounted rockers and guide plates. As was also posted, offset rockers and modified guide plates were used to correct this problem and indirectly solved the spring clearance problem.

  8. #8
    Senior Member DYNO OPERATOR
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    With the best quality Ti-17 Professional Grade Retainrs the retainer OD is smaller than the spring OD. There is no reason for the retainer to be as large or larger than the spring.

    AS was said, You may have raocker arm geometry issues from a pushrod that is too short. Don't just buy a longer pushrod. Check them for correct geometry using a good adjustable checking pushrod and the principles at Jim Miller's Mid Lift webpage.

    Rockers can be carefully cut for correct spring clearance if all is in alignmnet and the geometry is correct.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  9. #9
    Senior Member EXPERT BUILDER
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    Some times going to a lash cap and a longer push rods will help. We use Crower stainles rockers on our engines with big springs as they have plenty of clrearance every where
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  10. #10
    Senior Member RACING JUNKIE
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    Quote Originally Posted by hink
    Some times going to a lash cap and a longer push rods will help. We use Crower stainles rockers on our engines with big springs as they have plenty of clrearance every where
    Yep lash caps and the correct pushrod, is the only way to fly, i run lash caps on everything i build also no matter who's rocker arm.

    JMO

    Zip.


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