i just grabbed a set of 906 vortecs and wanna use the comp xe274 but heard my vortecs can only handle .470 lift and the cam has .490. i heard somehwere i can get .050 keepers and umbrella valve seals but cant seem to find the keepers. i plan on keepin the stock valves in it and upgrade to beehive springs with this cam. where can i find the keepers and seals? or any other way to allow this cam without machining? also heard i can run th stock vortec rockers with longer pushrods?

 

I would just mess around with seals til you find something useful. Take a gander at these, email alex himself and he may have some good advice about which seals to use with stock valves etc:

http://www.alexsparts.com/categories...TEC%2C-GEN-II/

From there, I would suggest you NOT use his spring kit because I think all he does is the infamous "ghetto grind". You can do that yourself if you really want to.

With a flat tappet setup, i would suggest you run some GM LS2/LS3/LS6 yellow springs. They're now made in blue instead of yellow, but you may find more results researching the "Yellow" springs as the color change was only made in the last 6 months or so I think. They are good to .550 lift at their factory installed height (1.8 inches), but they're too soft for aggressive roller cams. They are GREAT for medium flat tappet cams. At 1.8" they are 90 lbs seat pressure, a little low for flat tappet. At 1.75 they are 105lbs seat pressure, and that's about perfect for a medium flat tappet cam. You lose .050 from your max lift of .550, but the xe274 maxes out at .490 lift on both lobes, so it works out perfectly. You can use factory keepers, and use Comp 787-16 retainers.

http://www.summitracing.com/parts/NAL-12499224/
http://www.summitracing.com/parts/CCA-787-16/

http://www.summitracing.com/parts/CCA-4930/

And then I think these are about the same as the seals Im running on mine:

http://www.alexsparts.com/valve-seal...-32-x-480-510/
And while you're at it...

http://www.alexsparts.com/products/S...015%22%22.html

If you stack a .030 and a .015 shim that gets you to 1.755" installed height (measure measure measure! This is pure maths!) and right at 100 lbs seat pressure. At 1.25 thats right at 295 lbs open pressure.

Lets compare to xe274's recommended spring... Comp recommends BOTH the 981-16 AND the 986-16

LS2/LS3/LS6 Blue springs:
105 lbs @ 1.750
295 lbs @ 1.250

981:
105 lbs @ 1.700
273 lbs @ 1.250

986:
132 lbs @ 1.750
293 lbs @ 1.250


If you want, you can actually shim the LS2/LS3/LS6 springs another .015 or whatever and still be good to go, get maybe 110 lbs seat pressure if you end up having valve float issues.

The thinner retainer of the 787-16 should get you clearance for .550 lift as far as retainer to guide clearance goes. So you're good on that front too. I think the softer seat pressure will make the break in a LOT easier on the camshaft too. You'll be a lot less likely to wipe a lobe that way.

Just remember that the beehive retainers will get you around .100 more retainer to guide clearance than stock, but the springs need to be properly shimmed to get you to the right spring pressures, so you can have enough room for .550 lift, but not enough spring for it. To shim up the spring for more seat pressure you will lose lift clearance. The LS2/LS3/LS6 springs begin to fail when pushed past .550-.570 lift, which you should subtract whatever you shim the springs up to form that. If you shim the springs up .045, then they're only good to .505-.525 lift. And I would, from what I've discovered in my research, definitely stay closer to the lower bound and not push things. Theyre excellent, reliable, factory springs from GM, and as long as you dont push the boundaries on them you're fine.

If you want to run a big honkin flat tappet later on, or run a retro roller that needs more pressure, the comp 26918, 26915, and any other high performance LS aftermarket valvespring will drop straight in no problem.

Just always measure. But this should be very close to the right ballpark for you. Just remember to add up the costs of going the beehive route, and then talk to a machine shop about machining down the valve guides. If you can use Ls3 springs, they cost about the same as the aftermarket 981/986 springs, with the only added cost being the new beehive retainers you need. Later on if you have to use high end beehives later on for a big flat tappet or a roller, they're nearly $200. But you can always go ahve the guides machined later at that point. Just be aware that once you need to go to an aftermarket beehive the advantage goes back to just getting the heads machined.

 

well actually man, i found a howards flat tappet hydraulic with a 280 duration and a .420 lift on both sides. vortecs dont need crazy lift so im gonna go with that, can i run that with stock parts and just upgrade springs?

 

You'll make a LOT more power with the xe274, but if that's what you want to do it'll be fine.

 

cuz right now, its a daily driver from school to work and home. if i project 350hp from it id be happy, as long as i can crush them fox bodies lol. maybe in the future ill go xe274, but for right now what im lookin at will do better for economical reasons

 

Id be surprised if you broke 300hp with that cam. You might get 310-320.