Have a need for opinion...I recently aquired a complete Vortec 5.7L longblock (anybody want heads?)that was in excellent shape, with the exception of a worn rod bearing. The valvetrain is a roller type and is in excellent condition. I have heard good and bad things about GM roller valvtrains, particularly the pushrods and lifter retainers. Will the factory valvetrain hold up to a 450HP 6000RPM motor? I thought about changing the pushrods, I know I'm going with roller rockers and new springs for sure. Anybody have failures with GM valvetrain parts? The lifters look fine, just double-checking GM's reputation for roller lifter durability. Just making sure it's done right. I'll be using an LT4 Hot Cam. Heads of choice are 'Vette ported. Changing crank so thinking about 383. Thanks

 

Anybody? I know this is a 'rare' question but need to know if anybody has used a similar setup (GM roller).If not, I'll assume I'm one of the only with a stock GM roller valvetrain (Vortec). Thanks

 

The lifter retainers are fine, they are just there to keep the lifters straight in relationship to the camshaft. I really like the vortec heads more than the alum. vette heads. But thats your choice. Don't the vette heads have pushrod guideplates? I know they have screw in rocker studs (L98 is it, don't keep track anymore!?) I would recommend some Comp Cams hardened pushrods for those (roller cam length of coarse) My Firebird has the LT4 Hot cam, and I am using those pushrods and the GM crate engine lifters (Kit P/N 12371042) supposed to have a higher checkball spring preload than production.

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-Joseph
ASE Master Automobile Technician
Scoggin-Dickey Chevrolet

1967 Camaro (Vortec Heads, GM ZZ4 intake manifold, ZZ4 roller camshaft)
1992 Firebird (Weiler Vortec Heads, LT4 Hot Cam, GM ZZ4 Intake, Edelbrock 750, eventually will be Ram-Jet)

 

How much are those lifters? If they are superior I might as well get them. I work for a Chevy dealer too. Cool you work at SD. I'll change pushrods, don't want to risk anything, changed my mind against using the factory rods, so I'll go with the Comp Cams rods. I never heard anything about the Vortec heads being superior to aluminum 'Vette heads...are they, and in which way? I might send those to be ported if that's the case. The engine is complete, just needs a crank (383 Vortec?). I don't trust the pistons, I'll get a D-cup low comp piston so I can use boost in the future if I want to. The motor's going together pretty soon, as soon as I quit changing my mind. Thanks

[This message has been edited by dhirocz (edited April 07, 2001).]

 

My price on that Lifter Kit was $160, not sure what the markup price would be. Everything I seen was the uncut vette heads flowed less than the vortecs. Although I've seen those heads ported out doing very well. I used Speed-Pro Hypereutectic Flattop pistons in both of my engines. The 350 I have built for my Camaro is a complete vortec out of a 99 Suburban. You'll have to remember that the vortec intake bolt pattern is different, and the intake ports are higher in the heads and don't match up to factory intakes at all. I of coarse had the heads machined for the higher lift and better springs, didn't do any porting.
There was a magazine a few months ago showing the flow charts of the vortec, and the fastburn heads. It didn't show the alum vette heads, but if you can find that magazine (GMHTP or Car craft?) it'll show you what to look for in flow characteristics. The vortec intake runners flow great, the exhaust could use a little help, go with a 1.6 exhaust valve and port the exhaust port out. Leave the 1.94" on the intake side, it'll flow more than a 2.02"! - because the valve flow will be hampered by combustion chamber interference.
If you go with the 383 that'd be cool, I had a 383 in my Camaro before this new engine.
There's a 94 vette running around here with a LT4 383 and the Hot cam that dyno'd at 512HP at the flywheel.


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-Joseph
ASE Master Automobile Technician
Scoggin-Dickey Chevrolet

1967 Camaro (Vortec Heads, GM ZZ4 intake manifold, ZZ4 roller camshaft)
1992 Firebird (Weiler Vortec Heads, LT4 Hot Cam, GM ZZ4 Intake, Edelbrock 750, eventually will be Ram-Jet)

 

The Vortec heads do flow better in the low lift areas. They have the same raised exhaust port as the 'vette heads (.100 higher) and the same heart shaped combustion chamber as the fast burn heads. They also have more flow on the intake side. All around they are a better choice.

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Chronologically challenged. But still kicking!
'92 CAMARO RS
305 TBI 5/spd (now TPI)
B4C Alt.
'69 camaro-BB/Lenco,1050 dominators, /Pump Gas/no drugs 8.97-150+/3200lbs.
SoCal Thirdgen F-Bodies

 

The cast iron vortecs lay a serious smackdown on the aluminum fastburns on flow in all areas under .520" lift. I have the flow charts but too lazy to send them up. After .520 the fastburns run away on them though. The vortecs sound pretty killer on any steet engine simply because.... Who runs a cam/ratio pushing over .520" on the street?

Those weak springs and pressed in studs have to go.... But otherwise they sound great from what I heard. Too bad my TPI is left out.

 

Well, everybody so far is for the Vortec's. If I decided to go with the Vortec's, how would I go about adapting the SR? Then I would have to change the base, probably...jeez!

I may just sell them anyway, since the 'Vette heads only need to be milled, they have already been professionally ported. I know they flow 233 cfm @ .500 lift, anybody know what the 'Vertec's flow? Too bad GM doesn't make them in aluminum.

If I keep them, I'll just do some polishing, if that's all that's needed. If they flow well, I won't do a garage porting job and risk messing them up. After all, they are immaculate and only have 41k on them.

Looks like I'm using alot of the original GM parts from that '98 Sierra motor! It needs a crank, so I'll get a 383, probably. Thanks, guys.

 

I've always been told that th Vortecs are amazing heads for a basic street engine, but anything more than that is asking too much out of them. I'd definitley have to say stick with the vette heads. On the other hand, i'm building my '80 up for 350-375 horsepower tops (enough for my 700r4 to take) so if you stick with the vette heads and want to get rid of the vortecs, let me know
steve

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1980 Camaro, '88 Police 350 engine, Headers, full exhaust, completely redone, my baby!
1988 Iroc-Z L98, MSD 6a, Accel coil, K+N's, Airfoil, Coolant Bypass, Flowmaster, Gears, Late model Bose, I like the 80 better

 

Steve,
How do I get in touch with you? Don't have your e-mail and it's not in your profile...I'm seriously considering selling the heads, since I need $$$ right now. The Vortec's sound great, but the 'Vette heads have already been machined. Truthfully, I'd like to keep the heads for a future buildup. Getting back to the point, I believe they majority of my valvetrain will be GM...lifters, retainers, cam (LT4 hot cam), valves, etc...I'll get aftermarket pushrods and springs. Why not? I have most of it and it's readily available. Any other suggestions? Thanks everyone for all your input.

[This message has been edited by dhirocz (edited April 08, 2001).]

 

Flow Numbers for Vortec and Iron 441

Lift-----------Vortec-------441
Inches-------In---Exh----In---Exh

.050---------40---25-----30---20
.100---------70---49-----55---45
.200--------139--105----110---83
.300--------190--137----160--118
.400--------227--151----194--133
.500--------239--160----201--146
.600--------229--162----203--148

Exhaust tests were done with a pipe, same pipe used for both tests. Source: Chevy High Perf Feb 2001

As you can see the vortecs right out of the box slightly outflow your L98 aluminum heads @ .500". Imagine what a cleanup on these and a slight milling (maybe down around 60cc) would do! Yikes!!! Have to stay conservative because they're cast, but you could probably get away with 58cc with fuel injection and good gas.

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'88 Camaro RS 2.8L
'88 Formula 350 (Too many mods to list...)


[This message has been edited by JoelOl75 (edited April 09, 2001).]

 

Damn! That suprised me. I thought the 'Vette heads would have outflowed the Vortec's by a little at least. The 'porting' job may have just been a polishing job. Hmmmm...