The title says it all. Which do I go with? Im building a 383 with 6" rods. Hotcam, and ramjet intake. Also do I have to run self aligning rockers with vortecs? I have guideplates and screw in studs. Will I be ok?

 

it might narrow it down some if you tell us what part of the car you're talking about. lol

 

What a moron I can be lol

Just goes to show how hard ive been thinking about this!!!

Im talking about the rockers.

 

there are 3 ways to align the rocker.

• guideplates
• smaller oval holes in the head (old OEM style)
• self aligning rockers

you can only use one of them.

since you said you have guideplates, im going to assume thats what you're going with.

you need NON aligning rockers.


if i had a choice, id get the pro magnums....

 

Agreed, if you can swing the money opt for the Comp Pro Mags, I'm very happy with mine and the trunion size on these dwarf ALL of the aluminies I've ever seen.

I ran the cheap Pro Form aluminum roller rockers for 2 years with no problems, but it was always in the back of my mind...what if they cracked since I've seen a few stresses aluminum bodied rockers. Aluminum will always stress, it's a soft metal and there' no way around it, as long as you are'nt running a huge bumpstick and keep an eye on them you will be alright. If I were to ever use aluminum I'd buy Harland Sharps since many racers run them with great results, and best of all they have a lifetime warranty if anything does happen.

But you wont go wrong with steel!!

 

Comp Pro mags here too.

 

if you dont have the $$$ for the pro mags,the magnums can be had for 90 bucks(if you shop carefully!) or so and are a true ratio steel roller tipped rocker.everyone i have talked to is very satisfied with them.that's what i will be using.
Eric

 

The pro mags fit center bolt valve covers right. On my last engine I used crane gold and I had to get the narrow body ones to clear the ceter bolt covers. I want pro mags this time around. Do they fit?

 

I would go stainless if giving the opportunity to buy roller rocker’s again. I am also using the Vortec heads with the Hot Cam and 1.6 non aligning RR. I had the machine shop work on the heads for the bigger lift screw in studs with guide plates but the one thing they forgot to do was widen the pushrod holes on the heads.

 

Its actually called fatigue. Since aluminum has an ultimate strength lower than SS, it cannot not take as many high stress cycles. Now if you really increased the size or polar moment of interia of the aluminum rocker then the stress would be lower then the SS rocker, so it would actually even..

Just to add all materials fail in cyclid loading unless they are designed for infinite life, which is generally around 1E6 or 1E7 cycles.

So how many cycles do your rockers see in a year?

 

Last pic, dialup beware

They fit on mine, the last pic shows the valve cover bolt "supports" in relation to how the rockers sit as installed. You need to grind down the lip on the bolt support (the stamped steel pieces running from one side of the cover to the other in the pic) to fit between the rockers, but it's easy to do.

Not sure that the pic there shows "after" I ground it, but GM just rolled the edge for strength, you just need to remove enough so that rolled edge disappears, and they fit with no problem. As you can see, you'd only have to grind down one half of the support too, not the whole length.

 

Hey, dyeager535, I couldn't help but notice that you have press in studs on the vortec heads. Are you going to swap them for screw in studs?

 

Good eye. Those should at the least be pinned or they will start to pull out. Screw it studs are the best way to go. When you get
the screw in studs you may as well get guide plates also.

 

As a matter of fact, no I wasn't.

For the cam I am running, I didn't feel it was necessary...GM didn't, why should I? The catch is that my application is a low RPM torque motor, so stud strength wasn't as much of an issue.

With that said, a couple thousand (if that) miles into the rebuild one of the studs snapped (theres a thread on it here, somewhere) and thus I just bit my lip, pulled both heads, and had the studs pulled and the holes tapped. Installed ARP studs.

I don't know when to start worrying about press in studs...the high HP 350's and 327's from GM (302 as well?) used press in studs, so they must work for something. Roller cams probably put more stress on the studs than the earlier cams though.

The way the stud broke, the machine shop said was a fluke, and someone I know with metal in his background said that it appeared the stud was weak from the factory, perhaps due to overheating at some point like in the thread forming process.

 

Typically hyd rollers cams need about 100lbs more seat pressure than a standard flat tappet, combin that with a more agressive ramp on both sides, it puts a beatin on those studs so there's no way to compare the "old" flat tappet grinds with the newer rollers since everything is different.

 

No, but the fact is, Vortec heads are designed for a roller cam with press in studs, albeit a weak one. Just trying to get across the fact that even in heavy duty flat tappet applications, press in studs were ok with GM.

They DO pull out, but a lot of that comes from age.