Does this head/rocker setup need guide plates?

Comp Cams says these rocker arms are supposed to be used with guide plates… no big deal, I’ve already drilled and tapped for screw in studs I would just need the guide plates and correct studs. But I’ve read you don’t need them if the hole in the head (where the pushrod goes through) is the smaller size. Is this correct and if so, do my heads have the “smaller” hole? They are Vortec heads so does that only apply to the older heads? Any help, information, and experience is appreciated. Thanks guys

I think you have to hog the holes out and use guide plates.,Hogging the holes is probably also dependant on how much cam you have,but I'm pretty sure with any lift and possibly just with the geometry change with the rockers your pushrods will rub and bind on the head. Did you check rocker geometry yet? The holes in the head are not to guide the pushrods you need self aligning rockers or guide plates.

Ricko1966 said:

I think you have to hog the holes out and use guide plates.,Hogging the holes is probably also dependant on how much cam you have,but I'm pretty sure with any lift and possibly just with the geometry change with the rockers your pushrods will rub and bind on the head. Did you check rocker geometry yet? The holes in the head are not to guide the pushrods you need self aligning rockers or guide plates.

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I haven’t checked rocker geometry yet. I’ve never done it before so I’ll have to do some learning. What’s the difference between self aligning rockers and not self aligning ones? Theres no difference between these and factory ones besides the roller tip, does that change the self alignment part?

Need guide plates unless you have self alighning rockers that have the ears on the body or narrow section cut in the wheel to keep them on the valve tip.

Original vortec rockers were like the black and white pic

Yeah, with the vortec heads or other '87+ heads, you either need self-aligning rockers or you need guide plates.

Ricko1966 said:

Original vortec rockers were like the black and white pic

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So if I get some self aligning rockers will I still need the holes hogged out? Just don’t want to pull the heads back off if I don’t have too. The cam lift is around .450, nothing crazy

bucket said:

Yeah, with the vortec heads or other '87+ heads, you either need self-aligning rockers or you need guide plates.

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Do the stud bosses have to be machined down for guide plates? I’ve heard some people say yes, others no…

Truck82 said:

So if I get some self aligning rockers will I still need the holes hogged out? Just don’t want to pull the heads back off if I don’t have too. The cam lift is around .450, nothing crazy

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If you put factory self aligning rockers back on it,you will probably be okay. Are you roller cam or flat tappet? If roller are you O.E roller or retro roller?

Truck82 said:

So if I get some self aligning rockers will I still need the holes hogged out? Just don’t want to pull the heads back off if I don’t have too. The cam lift is around .450, nothing crazy

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Truck82 said:

Do the stud bosses have to be machined down for guide plates? I’ve heard some people say yes, others no…

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You don't have to hog out the holes in those heads no matter what you do.

If the heads are already machined for screw in studs, guide plates should work fine. But self-aligning rockers will work without guide plates.

Ricko1966 said:

If you put factory self aligning rockers back on it,you will probably be okay. Are you roller cam or flat tappet? If roller are you O.E roller or retro roller?

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Flat tappet

I always check the valve train geometry snd clearance when I change anything. Milled head,different ratio rockers,bigger cam,roller rockers etc. Also do not run guide plates and self aligning rockers. Most guys don't but you are possibly leaving horsepower on the table or run the risk of breaking stuff or wearing parts out premature.

Ricko1966 said:

I always check the valve train geometry snd clearance when I change anything. Milled head,different ratio rockers,bigger cam,roller rockers etc. Also do not run guide plates and self aligning rockers. Most guys don't but you are possibly leaving horsepower on the table or run the risk of breaking stuff or wearing parts out premature.

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I should be good without drilling those holes out? My cams just under .450 and my rockers are 1.52

I use the half lift method because it's what I learned at work in the 80s it doesn't seem to be the preferred method anymore people are using contact pattern. Anyway if you look at a see saw.it has the very most up and down movement on either side of just level. It swings in an arc so as it comes down it not only comes down but it also is traveling towards the pivot point,so some of the up and down is now side to side motion.(The side to side motion costs you lift and duration) The more up and down motion and less side to side means the valve is moving in and out the most)If you change the lift on the cam you change the start and stop point of that
arc. If you change the pivot point or the height the rocker contacts the valve you change that arc.If you mill the heads now the rockers and valves are lower but the pushrod starts and stops at the same old point.If youvrun longer valves,etc. If you are starting or stopping the rocker any lower or higher than necessary you are creating side to side pressure on the valve guide as well as losing lift and duration you payed for. Also that geometry also determines where the pushrod ends up in the hole in the head.

Truck82 said:

I should be good without drilling those holes out? My cams just under .450 and my rockers are 1.52

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I would think so,but if it were mine I'd check rocker geometry,might be over your head( no insult intended),I didn't know about it until I got a job where they taught me,so it's easy for me .