rnx

Hi,

Simple question, that different places have different answers - do I have to comvert my heads for screw in studs if I want to use polylocks? Some manufacturers say that I shouldn't use stock studs, some do not say anything about it. All local mechanics that I have spoken, don't know, as they haven's seen any full rollers in stock SBC heads.

Could anybody explain if and why should I replace the studs?

thomas1976

On centerbolt valve cover heads, without guide plates you need narrow body self-aligning rockers http://www.summitracing.com/parts/SCC-SCP1035BL/

For centerbolt valve covers, with guide plate: narrow body http://www.summitracing.com/parts/SCC-SCP1000BL/

For detailed pics and more information try a search
http://www.dartheads.com/dartboard/s...62&postcount=6
https://www.thirdgen.org/forums/tech...cker-arms.html
https://www.thirdgen.org/forums/tbi/...ng-vs-non.html
https://www.thirdgen.org/forums/tech...er-rocker.html

The polylocks should fit the stock rocker studs, not 100% sure try to serch.
Screw in rocker studs are used for mild+/high lift cams .470 +, some people just use pins to anchor the pressed in rocker studs.

UnderCover89TBI

iTrader: (25)

Yeah I have read with over .470 lift you can run into problems. If you think switching to roller rockers is going to give you HP. Your mistaken. 1.6RR will give you some. But with the stock tune. People on here have said you can run lean from what I have read.

rnx

Well, I think about 1.6 rollers anyway. Could help a little bit with torque as I understand.

After all the mods I have done, I should change my ECM tune anyway, so it's not big deal to change the fuel mappings.

92droptopws6

iTrader: (10)

If you have the stock cam you should not have any problems with the addition of 1.6rr. The studs should be fine, they can be pulled up due to age however i had a 495/502 cam on stock studs for over a year and no issues.

rnx

Thanks for replies.

I have '91 vintage 187 casting heads (yes, I know what you all think about them) that I ported myself. Just port matching, slight pocket porting, removed casting marks from top side of intake runner, trimmed conservatively swirl ramp, trimmed sharp edge from exhaust valve guide, polished exhaust runners and combustion chambers.

I will use LT-1 cam from B body car, that should give more torque at lower RPM, I think the 1.6 ratio rockers should be fine. It's completly dayly driven summer car, so I think low RPM torque is more important than XYZ Hp rating at non useable RPM range. I plan to use stock TBI unit with modified pressure regulator and TPI stock fuel pump.

Self aligning vs. non-self aligning rockers - as I understood, I dont need self aligning type rockers, if I have elongated pushrod holes? My heads have this kind of holes, does it mean, I could use non-self aligning rockers (cheaper ones)?

Dark Ember

I have installed crane gold, narrow body, self aligning 1.6 full roller rocker arms in my bird. The engine is internally stock, except for those rockers. Its been over 3,000 miles and no problems so far.

I also installed 1.6 roller tip rocker arms in an internaly stock 150k mile L69 305, and the studs began pulling out. Other people with the same engine normally don't have that problem, I appear to be a thankfully rare case.

Moral of the story: you "should" be fine installing rollers on stock press fit studs, but there is always that tiny chance they could pull out.

thomas1976

For the 187 heads you need self aligning.
With that cam it will make also more power @ 4500rpm, a coustom tune is a must if performance is the goal.

Rocker stud moods http://www.maxchevy.com/tech/2007/ii_12-stud-1.html

rnx

Thomas, could you explain, why do I need self aligning rockers? It seems that pushrod touches the side walls of these slots, as I understand, there shouldn't be the need for self aligning. Or am I missing something?

Btw, my car originally was bought in Switzerland, I am second owner and the car is in Estonia now. Do you have many of these there? It seems that most Estonian F-Body's are originally from there

thomas1976

If I remember correct the slot in the 187 is too big to be used as guide, though I never tryed, but thats easy to werify, can check alignment with loose stock rocker to get an idea. They come with self aligning rockers and not hardened pushroads from the factory.



Yes lots of them here, a lot of US cars in general, maybe because of history?
GM cars were assembled here from 1935 to 1975.
Louis Chevrolet was Swiss http://en.wikipedia.org/wiki/Louis_Chevrolet

rnx

Am I right then, if I say that I should machine the bosses, get guide plates, screw in studs and hardened pushrods, if I want to use non guided rockers on these heads?

I want to use those Skip White stainless steel rockers, as I have read here these should be really good deal for the money. But they are non-self aligning type.

InfernalVortex

iTrader: (4)

I have regular-body full roller rockers on my vortecs, no problem. I have guideplates and screw in studs, but neither of those allowed me to run "wide(?)" body rockers. It's just about getting the right valvecovers. I have tall valve covers and the supports near the center bolts are much different than stock. But you could modify stock covers fairly easily.

But if you havent bought them yet and you can find the same part in a narrow version, you might as well go for it. I personally just didnt care. I dont think my rockers were available in anything but their normal configuration at the time I got them.

Also:

Non self-aligning -> need guideplates -> Need Screw in studs
Non narrow body -> need clearanced/tall valve cover
.470+ lift/higher pressure valve springs -> Need screw in studs

If you're .470 or lower I wouldnt worry so much because your valvespring pressures may not be so high. Depends on your valve springs though, but .470 is the general rule of thumb. Note that, as far as I know, you cannot have guideplates without screw in studs. Maybe you can, but it's fairly pointless. They're machining down the studs to install the guideplates - trying to reuse the press in studs would be kind of stupid if it was possible. If you go with screw in studs I'd go with 7/16s ones unless that limits your options as far as parts availability for your application. I have 3/8s studs and wish I had the foresight to go with 7/16s.

rnx

I took a pushrod and put it into the slot - well, it's almost snug fit,maybe 0.05in or so side to side movement. Do I really need self aligning rockers?

UnderCover89TBI

iTrader: (25)

Do you want the pushrods rubbing a hole through the head?

rnx

I'm little confused now - I have elongated holes in the head, the pushrods touch the sides of the slots, and you say that I need either guideplates or self-aligning rockers or the pushrods will wear the holes? I dont understand. If I need to convert the stud bosses for guideplates, can I use the guideplates with these slots, or should I machine them round too?

thomas1976

If the rocker alignment is right, you do not need guide plates.
The pushrod should not wear the heads.

Makes me wonder how much you save by buyin cheap rockers, pushroads and tall valvecovers vs getting regular narrow-body quality rockers.

rnx

I already have tall valvecovers. I viewed some Comp Cams rockers at summitracing.com, but these that will work with '87 up heads were about $250 kit. If I add there $25 for handling, about $70 for shipping and approx 25% local duties, then they are too expensive for my budget at the moment. If I would live in the states, I definately would buy some Comp Cams or Lunati rockers. If someone can refer me steel full rollers, that will work in my application and does not cost arm and leg, then I would appreciate it

UnderCover89TBI

iTrader: (25)

Yeah I'm sorry I should have said it shouldn't but I guess it could...but probably only on aluminum

iggy1991

U will need the self aligning rocker arms. I have the 081s and yes it looks like the factory holes will do for keeping the pushrods in place but they are too far down to guide the pushrod. guide plates are put higher up closer to the top end of the pushrod. U could always try to run it and at 4000rpm a pushrod goes through the valve cover and bends up the rocker arm. I wouldnt chance it. I got the self aligning comp cams kit that comes with roller tip self aligning arms and new pushrods. Get the right part now so you will save urself a costy mistake later.

thewizard

iTrader: (43)

Another reason why some say not to use polylocks on stock studs is that the studs have inconsistencies from the manufacturing process that can cause the locks to seat oddly and loosen up over time.

If you don't want narrowbody rockers you can trim the inner valve cover supports on the intake side for clearance; lots of writeups online with pictures of that process.

Other thing to consider with 1.6s is those pushrod holes in the head....1.6s move the upper end of the pushrod towards the rocker fulcrum a little, and on some heads the pushrod will rub the head at/near max lift. There's a tool called the Louis tool that's used for clearancing that area.

xch3no2

That is horseshzit.

You don't use S/A rockers with any serious cam, rpm or spring pressure.

Obviously none yall have ever seen a pushrod deflecting at speed.
Harvey Crane Sr. was a pioneer of using high-speed camera for valvetrain observation.

Roller tappets & (big cams in general) require some kind of lateral control of the upper mechanism.

You can use EITHER guideplates (preferred) or the crappy option of self-aligning rockers, you cannot use both together.

As stated, the tops of the studs are best ground perpendicular to the stud axis to ensure a good surface for the locks to engage,...worth noting, they (the locks) must also be ground...avoid cheap sub-standard parts, you can trust ARP to provide what you need.

Hotrodding is all about the level of dedication your willing to apply.
Done right, it doesn't come cheap or easy.

I hope you are finding some good answers here.

You can give some guys all the best parts in the world & it just all falls apart in their hands, other guys only need the bare minimum to kick everyones azz.

...

Ryan3834me

Do the poly locks come with the Scorpion SCP1035BL ?

I'm about to order some rockers. I have L98 heads and a ZZ4 cam. (I already order my retainers and LS6 springs, also new lifters, pushrods) thinking of trying to machine for guideplates on the car. Or getting SA rockers. Hmmm.