This is my first time building bare aluminum heads and need a little help. When i align the roller tip to sit evenly across the valve stem and in the center. All of my "intake side" rockers are angled and the push rods rub on the cylinder head. A few of the exhaust rockers sit like this too but a few do sit straight. I have tried with and without guideplates and get the same alignment. Is this standard? Parts used if it helps (all new): Ebay bare aluminum heads Arp 7/16" studs Crane cams rockers Precision guide plates One piece pushrods Elgin SS valves Lunati springs
I believe to get what you need you will also need to change over to Shaft mounted rockers. I doubt you'll find them in single stud mounted rockers. It's a leverage thing.
Those heads don't need offset shaft rockers....They don't even need offset pushrod cup stud mount rockers... What you are seeing is normal standard alignment. Your mistake is thinking the rocker arm should sit straight and square...ever look close at a stock SBC head....the rockers on those fit "pigeon toe'd out" at the valve end also, you just don't notice it so easily because it doesn't have a narrower roller wheel there, it has a broad flat pallet tip. This pigeon toe fit is because stud spacing is narrower than the valve stem spacing. You can get two piece adjustable width guideplates if you want to try to get it to align a slight bit better, but from your picture it isn't a great deal off. Adjustable plates may be the ticket, or you may just need to loosen the rocker studs and shift the fixed width guideplate over a little, splitting the difference with the exhaust rocker. Isky Cams, and Alex's Parts have the adjust guideplates, Isky for about $75 and Alex's for about $30. https://www.alexsparts.com/adjustable-guide-plates-sb-chevrolet-w-5-16-universal-sbc/ Alex's are the ones I use, just as good as the Isky but you don't have to pay extra just for the name. As far as pushrod rubbing the hole in the head, that happens 95% of the time with any aftermarket head, it's common as hell - Dart, AFR, Brodix, ProMaxx, ProFiler, , RHS it doesn't matter whose name is on the box.....they are trying to maximize port width in that area. As with all aftermarket parts, don't just expect everything to drop out of the box perfect to fit, do a test fit of everything before you bolt stuff up permanent. You can either use the adjustable guideplate to get the pushrod off the casting, or rat tail file/Dremel the edge of the casting as needed. If the contact is no more than just enough touch to rub the black coating off a pushrod, then don't even worry about it, that slight touch will act as an additional stabilizer, much like you putting a soft touch on a guitar string to quiet it. If those springs are a dual spring, you are going to need to remove the inner spring for flat tappet cam break-in or risk a flat cam lobe if this is a new cam build. Hard to tell from the pic's, but it sure looks like a dual spring with a flat wound damper, if it is it will kill a new flat tappet cam in minutes trying to do the break in with them at full pressure. If you are planning a roller cam, then you don't have to worry about it. Heads appear to be the ProHeader/Assault/NKB/RPC/Power Products import copy of the Dart Pro 1 Platinum...the good imported Asian casting. Correct?? After a third look....do you even have guideplates on the heads right now??...as I can't see one. All aluminum head have to have pushrod guideplates to hold the pushrods and thus the rockers in alignment, unless you are going to use self-guided rockers.... and the rockers you've pictured are not the self guiding type. Along with guideplates you've also got to have hardened pushrods if the pushrod you currently have isn't hardened for guideplate use. ***Ahh, just read back through and you test fitted with and without guideplates….adjustables and filing are in your future, par for the course****
Ericnova72; Are you saying that it's okay for the pushrods to Not run true vertical to cam line up to the Rockers and put thrust on a guide plate to hold things in place while Rocker tip lands at an angle to Valve movement? That's acceptable?
Yes, that is correct. In a perfect world we'd like them to all be perfectly aligned...but in the $2000 or less cylinder head market that isn't the case. Even Air Flow Research's instruction sheets address this issue. We are only talking a couple degrees of angle on the pushrod, and as long as we contact 80% or so of the valve tip width it will be fine. This isn't an 60/40 offset valve, no pushrod pinch full race head requiring offset stud mount or offset shaft mount rockers, it's a basically stock layout head...Dart and about everyone else moves the intake valve over .030" and that is some of the misalignment, but it doesn't mean anything bad will happen. The more I read here the more I realize there are not manty here that have put any real performance engines together with modern components....most of the info posted is stock related or old 1970's tech a lot of the time.
I have to admit I'm part of the "Over the Hill crowd" and what actual Motor machine work I did do is 30 years old. That said I haven't walked away from Horse Power. Having motors in pieces and back together isn't unusual here. I have 2 outstanding machine shops I still use. I was very close to the guys from Columbia Racing Engines and still am with the ones still with us. I'm still playing a little with a 1200 hp single Carb'd Cash Hole. I think I'd take issue with my pushrods having a side load in the guide plates on a post mounted rocker arm. Simple physics tell me it's a Train Wreck in motion. You can kill performance motors easy enough without lighting the fuse yourself. I know a lot of things change with time but I don't think the Law of Physics ever will.
In an SBC, the valves are approximately 1.9" center-center. The rocker arm studs are approx. 1.80" c-c and the lifters are approx. 1.7" c-c. The push rods are a few degrees off from true vertical. The rocker arms must have a little splay to center on the valves. I have had the push rod rubbing at the intake pinch point on Dart heads, ProComp heads, and my new Profiler heads. All needed a little massaging in that area to eliminate rubbing. I don't like the look of those splayed rockers either, but it is what it is.
Then how does a Big Block Chevy EVER survive 5 minutes of run time by that logic....pushrods at different angles than both the lifters AND the rocker arms, pushrods side loaded up against guideplates, and studs at angles from everything??! If you don't actually know the answer to the OP's question, don't just toss out a guess and then try to backpedal justify it with a smoke and mirrors diatribe about the knowledgeable people you know or the big HP you've been near(but seemingly know little about technically) and then finish it off with Mr Science Guy and the "Laws of Physics". Give the OP real truthful advisement, and not some shade tree guess. If you don't actually know, don't throw out some bogus answer. The head JMax has is a stock configuration aftermarket head, not an offset valvetrain race head. As mentioned in a later post by Jaw22w, lifter bore spacing, rocker stud spacing, and valvestem spacing are all different dimensions, even on stock heads. Aftermarket manufacturers manipulate the stud spacing and location and/or the valve spacing location in small amounts(.010" to .030")on these "stock configuration" valvetrain heads in some small amounts to foster airflow improvements, but not so much as they require expensive shaft rocker systems. Like I said previously, even stock rocker arms on stone stock heads run pigeon toed out, it is just less obvious to the eye because of the size and design of the rocker tip, ...stock rockers "hide" the angle, roller tip rockers and aftermarket heads amplify it. The accepted method of dealing with it is adjustable guideplate(or cut in two and weld a 1-piece guideplate to fit) and filing or Dremeling the needed pushrod clearance from the casting wall. You won't see me giving bogus advice on Flathead V8's or Chrysler Poly's, because i know very little about them
Like he said, adjustable guide plates, Comp Cam #4835-8 Lots of people wouldn't have caught that, good eye and smart to ask.
I understand your problem as i have the same one. I've dealt with this in the past with Dart iron eagle heads.. the answer guy is correct, you can gain with adjustable guide plates. But your problem is the same as mine! your roller is barely touching the valve tip. The only solution I've found is adjustable guide plates WITH offset rockers. Do a search for Harland sharp rockers, you can get them up to .150 offset, expensive but necessary
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