Ok I have been at a stand still trying to figure out the least expensive way to get my Vortec heads to work with my ZZ3 cam. People who know tell me that I need springs to handle the lift. Problem is I have to get the heads machined to accept larger diameter valvesprings. That was until I found GM's Z28 springs that are the same 1.25" as the stock Vortecs and are good to .525 lift.

My question is if I use these springs with the zz3 cam will I run into any problems? Is there anything else I should be aware of? Is this a true bolt on mod?

Any insight is helpful and appreciated.

 

I would not trust any 1.25" springs at above .500" lift, period. A number of people on this board have run into trouble with the LT4 HOT cam and others, when they believed GM's claim.

Remember: these are the very first "performance" valve springs GM has ever sold. They're brand new at this game. I'd trust the cam mfrs that have been dealing with this for decades now, long before I'd believe GM's claim to have the only 1.25" springs on the planet that can survive in that application.

The cam mfrs (Comp, Lunati, Crane, etc.) will not warranty any cam/rocker combo used with 1.25" springs if it gives more than .500" lift at the valve. That should tell you what people with experience have found to be reliable.

You're going to have to machine the heads anyway if you want to run any valve lift beyond .480" or so, because the retainers smash into the top of the guides at about that much lift; might as well get the spring pockets opened up at the same time. The added cost will be negligible or maybe even zero. Just do the machine work if you want to run the parts.

So, no, in the strictest sense of the words, that combination is not a bolt-on at all.

 

I was running 1.25 H-11 springs on my cam. This is with .510/.520 lift. It worked well, and if I had machined the guides down, all would be good now. But I didn't, and they started to break the inner dampner. I never had the warm fuzzy feeling, knowing I only had .030 clearance between the retainer, and the valve seal. I destroyed almost all the seals. The point is, machine for bigger springs. At the least get the springs that come with the LT-4 HOT cam kit. They are like $35 from GMParts direct. THe tool to machine the guides, and the spring pocket is only $20 for the arbor, and $40 for the cutter. I am waiting for mine now. Warning though, they are on back order until mid March.