Im usin some GMPP vortecs for my 383 build (mild for a 383, but this will at least get the car movin). The guy Im buying them from is selling them assembled, along with an edelbrick vortec intake, and edelbrock elite valve covers (to match my air cleaner) for $460. I figured it was a good deal, considering everythings got less than 2k miles on em.

But, the cam im using is comp xe274, with 230/236 at .050, .490/.490 110 lsa. This looks liek the perfect cam for the stroker, good duration, mild lift. Has anyone modified the vortecs themselves to get more lift? Ill be usin 1.5 RR, so .500 lift wud be the max Id want, plus Ive heard vortecs lose power after that.

Just kinda curious if anyone else has ventured this route, or if they pay the machine shop to do it.

 

It can be done. You will have to have the guide bosses milled down a tad to allow for more clearance between the guide boss and the bottom of the retainer. You could also run taller valves, use offset retainers/keepers as well, however, changing the installed height of the valve springs isn't the brightest thing to do.

I would just run them to a shop and have them mill the guide bosses down. While they are in there, might want to consider installing 1.6" exhaust valves as well. Think about screw in studs, too. Perhaps even guide plates.

As far as power is concerned, it's not that they don't make power up there directly, it's that the peak lift by factory Vortec ports is achieved at .500" (or is it .550" I forget).

 

Im trying to avoid the machine shop, trying to be on the budget side right now and save the machining money for some really good heads down the road.

I think I found the cutter I need. But, see if you can stay with me through these measurements:

From Sallee Chevrolet's website:
Stock L31 Vortec Heads

Spring seat- 1.300" OD, .850 ID
Springs: 1.235: OD, .875" ID

meaning .025 clearence between the spring and the guide right? well the cutter Comp is recommending for Vortecs is this:

#4716- "used to install larger valve springs & hardened spring seat on GM Vortec head. Cuts seat to 1.320", .630"

Springs Im going to be using are 1.254" OD, .820" ID (#981 from Comp)

meaning, if I use that cutter, I would have .19" clearence between spring and guide. Compared to .025, that seems like a lot. Didnt know if that clearence needed to be precise, or just not too close. Im guessin that as long as there is at least .025" between guide OD and spring ID, im good. Too much clearnce wudnt be an issue.......or is it?

 

But does that tool also cut down the valve guide?

As was mentioned, the guide bosses are too tall for much lift. I'm running a cam with .452" @ .050, and there was JUST barely enough clearance according to conventional wisdom. The clearance you are looking for is between the valve spring retainer and the top of the valve guide at max lift.

Cut the spring seats, the stock vortec springs won't handle much either, and the retrofit ones I've seen specific for Vortecs are very expensive compared to "standard" springs, and you don't have many choices.

These heads (stock) add a lot of hassle for higher lift applications.

 

That has to cut the guide as well to get the .630" ID.

 

Wasn't really referencing the guide diameter, talking about guide height. With the rail rockers, the spring retainer gets close to that guide with minimal lift.

I would hope it did all three at the same time, but that seems like a lot for one tool to do.

 

well, from what Im seein, the cutter itself deals with the spring seat, and the arbor you use hooks to the drill, and sits in the valve guide itself to guide you down straight, and it also cuts the guide height.

But still, Im not seeing any cutters that will work for these particular springs. Ill try crane or someone else, dont look like Comp's gonna work out, even though Im using THEIR springs

 

The ID doesn't have to be that close, if the OD holds the spring in place (as it will in that case).

Meanwhile, if you're going to go to all the trouble and expense of cutting the seats and guides, put some real springs on it; not 1.25" singles. That's just plain boneheaded.

 

These are the springs that are in the cam kit I got from comp. Ill have to call them or look on their site to see what the larger equivelant is for that cam.

As far as the ID of the seat, I figured that pretty much held the spring in place so it doesnt bend or flex under lift. ID and OD work in conjunction, like OD keeps it in place horizontaly, and the ID keeps the spring vertical so it doesnt warp/flex/bend etc. Am I wrong on this? still trying to get all the math right, my minds kinda fried at this point

Oh, about the springs, u dont think that wud be good enough for a hydro flat cam? I know its not an all out drag car (yet), but I figured that wud be pretty good.

 

Yes you are wrong on that.

Otherwise, positive seals on the valve guide such as these, would have a very tough time.

If you're going to spend money to work on something, get the most bang you can for your buck. That tool is going to cost you somewhere in the $80 neighborhood when you finally find it at Manley or Isky. It costs the same to take the spring pockets out to 1.45" so you can use better springs. The better springs cost about the same. That 's what I'd do if I were you; get the tool that takes the pocket to 1.45" so you can use good springs such as Comp 986, the guide OD to .530" so you can use the Teflon seals, the guide height down to .600" or whatever it is so you can run the lift you want to run without the retainer smashing into the guide; all for the same price a sthe little bit of nothing you're talking about spending the same money to get.

Oh, I almost forgot, the seals....

 

I used that same cam in a 383. With 1.6 RR. Comp says that the powerband is 1800-6500. But I had to switch to a 3000 stall convertor because I dident get any power untill almost 4000 rpm. It made very good top end power though.