Diabolical

i am building a 350 for my trans am. i bought a set of aftermarket vortec heads. i have comp cams roller tip rocker arms w/ guide plates. when we went to install the heads, we put a head on, put a lifter and pushrod (stock size) in, put on a guideplate, and started to bolt on a rocker arm. the rocker arm went all the way to the bottom on the threads, and was still short of the pushrod. thinking that vortec heads use longer pushrods, we called a gm dealer, and he said they use the same length pushrod. then i called the guy i bought the heads from, and he said that i can't use those rocker arms. he said we need to use pedestal mount rocker arms. when i looked at gmpartsdirect, they didn't even list any pedestal mount rocker arms, so i'm skeptical about that. what kind of rocker arms should i use?

RB83L69

The rockers do not care whether the heads are Vortec (raised intake runner) or not.

Sounds to me like you have push rods out of a roller motor and you are trying to use them with a flat tappet cam. If so, they'll be about .500" short.

Use the same kind of rockers you would on any other head. If the heads have large holes where the push rods pass through (they should) and guide plates, you'll need non-self-aligning rockers. DO NOT attempt to use self-aligning rockers on the combo you describe, you will surely have major binding.

88ROC1LE

iTrader: (4)

*Self-aligning* is what I'm using on my Vortec's. I have the 1.6's from GMPP.

RB83L69

88: Do your heads have guide plates? If not, then those are the right rockers for you, but the wrong ones for Diabolical.

Bottom line, the push rods do not care that the heads have the raised intake runners; the error in their length is because they are for the wrong type of lifters. This has nothing to do with the rockers or the heads.

Diabolical

the pushrods are 7.8" when we use them with my stock heads, pressed in studs, and stamped rocker arms, the pushrod is the right length. when we use them with the vortec heads, screw in studs, guide plates, and roller tip rockers, the pushrod is at least 1/2" too short, might even be closer to a full inch too short. the guy i bought the heads from insists that they use 7.8" pushrods. he said that i need to use pedestal mount rocker arms. i cannot find a pedestal mount rocker arm for sbc in jegs or summit, all i see is like oldsmobile and ford. btw, the original setup in the motor had a solid cam, and now i'm using a hydraulic cam.

pre

I believe your supposed to use self aligning rocker arms with vortec heads.

F-BIRD'88

Wondering if the rocker stud boss is not machined or not machined right.

.500" is a lot.

What happens when u try a old stock stamped steel rocker on the vortec heads?
Is the pushrod the right length then?

Are these Protopline Vortec 906 heads?

Is the cam a non stock Small base circle cam?

Diabolical

i haven't tried to put a stamped rocker on the vortec heads, i will try that sometime. i don't know much about motors (i have a mechanic helping me who is just as stumped) but even i know 1/2" is a lot.

yes, the heads are the pro topline 906 http://cgi.ebay.com/ebaymotors/ws/eB...tem=2426404699

here is my cam http://www.jegs.com/cgi-bin/ncommerc...97&prmenbr=361

johnsjj2

I might have missed this as I am very tired, but did the push rods come out of a factory roller motor? Those are to short like RB stated. If they came out of a flat tappet engine, then maybe it is the thicker decks of the Topline heads that is making them so far off. I have heard of plenty of guys on here having to get longer pushrods for almost all the Pro Topline heads.

88ROC1LE

iTrader: (4)

No, my heads do not have guideplates. SDPC matched these rockers to the heads for me. I was under the impression that his heads were similar to mine. My appologies.