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New guy. Head issue

2K views 18 replies 9 participants last post by  ericnova72 
#1 ·
Hey everyone, new guy here from CT (well was a member years ago but havent been on in years), been lurking around for a while. I started gathering parts years ago for a 383 stoker. All forged bottom end, solid flat tappet comp cam. I bought pro comp heads a while back, with guide plates (yeah, probably a mistake), had them cnc ported and they flowed pretty good. Well finally got around to putting the engine together. One head is torqued down. I have a set of elgin stainless roller rockers, decided to put one on just to have a look, since i have no pushrods yet. I noticed that the one exhuast rocker stud that i set it on is way off center from the valve tip and doesnt look like the rocker will be centered. So then real quick i checked another exhaust....doesnt seem to be that much off, if it is at all. so I guess what im asking is, has anyone ran into this issue? am I pretty much screwed and need new heads? Thanks for any help. Also I am using 7/16 arp rocker studs, they came with 3/8. Attached a picture to give an idea of what I mean
 

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#3 ·
With out having a checker pushrod in place its hard to tell exactly. But looks as though the rocker arm its self with be hitting the valve tip when holding the rocker arm straight off the stud. so I think basically the rocker arm would be off center from the stud to actually hit the valve center. Not sure if that makes sense
 
#4 ·
SBC rockers and valve tips do not sit in a exact straight line square with each other, rockers actually sit slightly "pigeon-toe'd" outwards...even on stock heads.

You won't know where the rocker contacts the valve tip until you test fit the pushrods.

If alignment is off farther than you like, there are adjustable guideplates available, Isky Cams is one source.
 
#5 ·
Okay, thank you. So my checker pushrod should be in tomorrow. So I should set up the push rod checker so that my pattern is good and it's center on the valve tip, and then see where I am as far as side to side alignment is with the rocker arm on the valve?
 
#6 ·
Yes and no.

Hope that isn't one of those blue plastic deals, they are not correct.

Don't worry about being centered on the valve tip(that is old wives tale info), set pushrod length for the narrowest sweep pattern on the tip and just try to keep it in the middle 1/3 of the valve tip and no running off the edge.

Then you can worry about side to side alignment and the possible need to use adjustable guideplates or cut and weld the guideplates you have.

Here is a video explaining how to correctly figure your pushrod length.
http://api.viglink.com/api/click?fo...ulletin Board&txt=http://youtu.be/o5is9BsH5OU
 
#9 ·
I have a set of elgin stainless roller rockers, decided to put one on just to have a look, since i have no pushrods yet. I noticed that the one exhuast rocker stud that i set it on is way off center from the valve tip and doesnt look like the rocker will be centered. Attached a picture to give an idea of what I mean
. What caused you to align the pointer at the angle you did in the picture?
 
#13 ·
I did some research on the ProComp Heads when I saw some offered at a lower than normal price on ebay. It seems the problem you are having is a problem with those heads. I don't have the links but I'd advise a google on Procomp Cylinder Heads and you'll probably find the sites that I looked at. On some of the heads the rockers were so far off center that it actually destroyed the rocker and valve stem. I put those heads on my "Not to buy" list.
 
#14 ·
This is a common problem across a broad swath of aftermarket and factory heads, another good reason to buy heads bare as often included parts like the push rod guides and in your case the studs are replaced. GM production has the same problem so it's common with engines older than the self guided rocker engines to see a misalignment between rocker and valve stem. One of the nice things about self guided rockers is that they align to the stem then let the push rod take the angle if any since it has ball ends that allow this movement. Certainly this compromises getting lobe information into the valve movement. Racing for big bucks would cause the enginne builder to repair these slightly off dimensions.

In your case if you continue to use the Elgin rockers, or anyother unguided rocker, then Isky, Comp Cams and some others have split guides that can be used for fine side to side adjustment of the push rod to put the roller tip of the rocker straight on the stem tip.

Bogie
 
#15 ·
I'm in Wolcott. I'm going to go with a set of split pushrod guides. I've talked to a few other engine builders and it seems to be a somewhat normal issue. Was told that the rockers and valves can get destroyed by not aligning the rocker arm properly side to side on the valve, so the the actual rocker arm is running on the valve tip and not the roller.
 
#19 ·
Like I posted earlier, almost all SBC heads are like this, even stock heads are like this....the stud centerlines are closer together than the valve stem centerlines are. The last picture you posted is a completely normal SBC photo.

Some of the ProComps have had an issue with being a lot farther off, or with the stud bosses not even thread tapped perpendicular to the correct blueprint spec.

Only the use of shaft rockers will ever get the rocker arms square with the intake face of the head.
 
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