joe73vette

What's the real story with vortec heads?

Scoggin-Dickey says they can't take over .450 lift, but they want to sell their modified heads with Z28 springs and LT4 retainers.

GMPP uses a .435/.460 lift cam in their 350HO crate motor.

Chevy High Performance says max of .470 lift.

I want to use Comp Cams 265 Dual Energy .442/.465 lift or XE262 Xtreme Energy .462/.469 lift. Will either work?

What cams have you people been using with Vortec heads?

Thanks,
Joe

PS Is it the springs or the guides that limit valve travel? If guides, can they be hand worked a little?

smonska

The rocker arms you use will also make a difference, 1.6s definetly will cause bind. I know just the springs aren't enough to make the heads handle higher lift as a machining is done to the heads to give more lift clearance. I'm planning on buying a pair of the already done scoggin-dickey heads, but I know there was a BIG car craft article on "budget factory heads" that had all this info on vortecs, I'll look for it.

72rdstr

Check your email.
TB

Ironcross

Almost all heads will work as long as the piston fits the combustion chamber. Most heads will have to be reworked in the guide area to prevent coil bind. or retainer interference. Correct parts on a small block would be the 1970 LT1 springs and retainers. This would be satisfactory for both mechanical cams [ high rev 7000 ] and hydraulic cams [ 5800 ]. The guides would have to be machined down for the increased lift. Good running stock cams are the GM # 3863151 327/350 HP in a hydraulic mode and as a solid, GM# 3972178 used in the 370HP 1970 LT1. A set of 202 stock heads. with these changes will really improve performance and you don`t need any fancy aftermarket quick breaking expensive roller junk to get there. ;)


[Modified by Ironcross, 5:17 AM 11/15/2002]

Smokehouse69

I was planning on using an XE-262 and Vortec heads on my old engine until I decided to put in a ZZ4 instead. I still have a set of Vortec heads and the Comp XE-262 cam kit for sale if anyone is interested!
There are a couple of tools that are sold by Comp Cams that will allow you to widen the spring pockets and cut down the valve guide height with a 3/8" drill at home. The cost of the tools and mandril is less than $100.00, then you can use just about any springs you want. Chevy High Performance did that with the Vortec heads on their HT-383 test engine. Although they put on 1.6 rockers before they did anything to the springs and the car ran fine with no apparent coil bind of the valve springs.
Check with a machine shop, it might not be that expensive to get them to cut down the guides, then you could put on GM stock LT-4 springs and have enough lift to handle .500 lift with no problems and no coil bind.

American Boy

I checked the max clearence with the retainer that came on my vortec head and it's 0,575". A safety marge of 0,040" is recommended. So around 0,535" is the maximum lift without machining.

For the spring, Scoggin-Dickey have direct fit spring that fit these head without machining. You just have to take out the damper. As far as I know, the damper is for vibration in the valvetrain at over 6000 rpm.

I will use the XR-270 that have 0,500" lift with 1,5 ratio rocker.

Steph