I now have everything to put the vortecs on the ole 327. My last concern is the stock springs. They are brand new stocks. It will cost me $60 to machine the stock guides down. They are now 0.860". My preffered options are:

1. Use stock springs with my lunati 216/228, 454/480 lift cam. I have machined the guides slightly and the lift is now no problem. I won't be going over 5000-5500 RPM. My concern is the seat pressures. I know that Vortec stock springs are a little on the light side. Is anyone running the stock springs?

2. Install aftermarket springs without machining the guide bosses. Is anyone running an aftermarket spring that fits in the stock location without machining?

3. Last machine the heads and install aftermarket springs.(least preffered option).

I have read every post on this site and the 3rd gen site as well as the monte carlo site and they are mostly opinions, not experience, so I am really interested in people who have actually experienced the top two scenerios i listed above with the vortec heads.

I am running an XE-256 with stock springs. It works fine but I don't have as much lift as you.

I am running a XE268 cam with mine. It has more intake lift (.477) and the same exhaust lift...with a theoretical perfect 1.5 ratio rocker. However...I sent a couple of old stock rockers to another guy on the camaro board for him to check the effects of valve timing at the valve when changing from stockers to 1.6 rollers. They checked out closer to about 1.42 ratio...so even if the newer style guided rockers are more accurate, chances are they are still under 1.5:1. Anyway, I'm getting off on a tangent. On my vortecs, I used a set of comp 981-16 springs, and they dropped right in with the matching retainers. I did absolutely no machine work. Another guy on the camaro board used the exact same springs on his vortecs, and they would not fit over the guide. I personally would not use the stock vortec springs with any cam more than the mildest rv grind...they are quite weak (squeeze one in your hand and you'll see what I mean). It is my understanding that the cheap Z-28 style springs ARE a direct bolt on, and have pressure more in line with what is needed with a street hydraulic flat tappet cam. Around here you can get the Z-28 style springs made by Elgin for under $30 a set. Seems to me it would be a very worthwhile investment.

Remember vortecs are truck heads - trucks with slow lazy non-performance camshafts so those springs are not good for anything else. Have you checked to see what size spring Lunati recommends with that cam? Might actually already be a stock diameter "drop in" spring.

I checked with Lunati. They recommend the 47943. I can get them on e-bay for $50. I can't remember but they indicate that the inside diameter of it is 0.880 without the inner damper and I was hesitant to run them without the damper. I have no problem buying the z28 or 47943 springs as long as I new they would drop in without machining the head. Thats what i'm trying to avoid. What you said earlier is what I've been hearing. One person says that they drop right in and another says they won't fit. Did GM change the guide bosses. Mine are 0.860 and i have heard others say that that theirs are 0.900. Is there a recommendation on how much tolerance there can be between the spring and guide boss? Is 0.020" too tight?

Clyde,
.460" is about it for the Vortech springs. Most of the cam manufacturers have springs that will work.

I've checked the lift and there is no problem there. I have plenty of clearance (0.070-0.080")on the lift. My concern is with the performance end of the spectrum. What problems am I likely to run into by running a lite spring. I have heard about valve bounce. Is this very likely? How much of a performance hit will I take by running a new stock vortec spring vs an aftermarket spring with a higher spring rate. I understand that it could run into valve float but is this likely to happen below 6000 RPM? Most everything that i have read says that valve float is usually above 6000 rpm.

Clyde

I looked this over night before last and I will bet a 6-pack of "Pop" to a donut-hole that the CC 981 springs are Z-28, (or -142) springs..

Check out a Competition Products cat. and double check against the -981's if you want.... And I'm looking at the -981 spec's right here now..

AND another spring is the newer Chevy springs just below them in the C/P's cat. that I didn't realize they were selling.

For the money and conveneniece the -142's are hard to beat if you can run them.

Get a set and if they don't fit, do the right thing and get your guide's O.D. cut down a schosh to say whatever GOOD oil-seal you would like to run. I know I would and be done with the headache!!

pdq67

Valve float is more likely to happen at RPM's higher than you plan on going BUT proper valve springs are still very important. An aftermarket cam with fast and aggressive ramps needs a suitable spring or you're risking A LOT all over a little $30-60 set of springs. Is it really worth it the day you romp on the gas and a valve spring breaks and sends a valve into your cylinder ruining a piston, scarring the block, taking a chunk out of your head?

Its a relatively cheap part, replace it. The risk just isn't worth it. Another thing... did you buy your vortecs new or did you get them used like most people? Ever wonder how many miles those junky valvesprings had put on them before you got the heads?

Spring for the $34 Z-28 springs and retainers. They work fine for me up to 6500 RPM with .480 and .500 lift on a solid cam. Zero machine work involved. I have around 30,000 miles with these heads and springs with no issues. And I've spun it up several times.

I got rid of the stock Teflon seals and replaced them with umbrellas at my machinist's recommendation. This gave me clearance for way more lift than I'll ever use. Have had zero issues with oil leaking through the guides.

I ran stock vortecs with a comp 260H with no problems, but that cam isen't more then like .440" lift.

Originally posted by cjlandry:
Spring for the $34 Z-28 springs and retainers. They work fine for me up to 6500 RPM with .480 and .500 lift on a solid cam. Zero machine work involved. I have around 30,000 miles with these heads and springs with no issues. And I've spun it up several times.

I got rid of the stock Teflon seals and replaced them with umbrellas at my machinist's recommendation. This gave me clearance for up to .650 across the board (more than I'll ever use). Have had zero issues with oil leaking through the guides. =
=
CJ,
Problem is the Z28 spring will not fit on all Vortec heads without machining the bottom of the guides.
Some are larger than the inside of the spring.

And I am assuming the .650 lift was a misprint as regardless of seal I do not think you will be able get that much clearance without a longer valve or machining the guide down & using a different retainer/ keeper combination ;)
I have trouble getting to .600 on the flow bench on some with no seal & the early retainer.
Also the Z28 spring will not tolerate that much lift before coilbind.
=
Clyde,
I would just "bite the bullet" & get it done right the first time.
Beats the hell out of doing it twice :D
And to your question of valve float or bounce, yes it can happen well below 6000.
The more aggresive lobes usually need more spring than stock to control the valvetrain.

The heads were brand new off of a GM 383 crate motor, It had never been fired up so the springs are brand new as well. It looks like the GM Z28 springs will work so I just ordered a set off competition products. We'll see what happens.

Clyde

I've taken the old cheap Z- springs above 7,000 rpm many times, but they were only controlling a good old -097 Little Duntov solid cam!!!

I honestly think the Z- springs, (and the newer ones, too), can handle just about all street cams as long as they aren't too tall or "super hairy", imho....

pdq67

You're right, Mike, .650 isn't the right number, and I don't remember the exact measurement. "650" was stuck in my head, but it was parobably "560". The measurement was taken with no spring in place. Coil bind was not taken into consideration, only clearance between the retainer and seal.

It's been quite a while and I remember it being some crazy huge number compared to the "max possible lift" that I'd heard of with Vortec heads. I didn't believe the machinist when he told me, I had to get him to show me. It was definitely a lot more lift than I'd ever use with those heads.