so i have been asking around my work and alot of the techs there have been giving me diff. answers about what limits the valve lift on the vortec heads i have been trying to fined a cam for my 355 (tbi) geting it to make 300hp would be awsome also i would like the motor to have more top end power it was kind of discouraging when when i had my 305 and could kill all my friends 4 bangers off the line then on the highway i couldnt keep up to save my life so if anyone could tell me what the max lift of my 906 heads would be that would be awsome or even give me some recommendations on cams that would be good the heads have comp cam springs(986-16) and 10* retainers(740-16) and arp thread in studs with 1.5 roller rockers thanks for the help

 

No telling.

Those springs and all that won't fit the heads in stock trim to begin with, so they've had some work done to them. They're a little off to the side of your monitor and too far in the background, so I can't see them quite well enough to tell exactly what. You could either ask the person who did the work, what they did; or, go get a pair of "check" springs (you could get something entirely adequate even from HD or Lowe's or Nard's, let alone a REAL hardware store) and measure it.

 

i got the heads stock and took them to the machime shop and had a 3 angle valve job decked and had the threaded studs put in then i put the springs and everything on my self . so why wont that stuff fit?

 

Because in stock form, the guides are too large OD for the inner spring to fit over them; and the pocket is too small for their 1.45" OD.

Therefore, if those parts all installed PROPERLY, they're not stock. Something has been done to them. No telling, from this side of your monitor, what all that might have included.

Best thing to do, as said, is to either ask whoever did the work what they did; or failing that, put some check springs on there and just measure it. Which is what I'd do anyway because it's about the same amount of work as dialing the phone and is AHELLUVALOT more certain.

 

ok so i went to check the valve springs on the heads and they dont fit right so what would be good valve springs to get for the heads ?

 

Couple of choices:

Do the machine work as detailed above, and while having the guide OD reduced, have its height reduced as well.

Beehives.

Sombody's entry-level 1.25" single springs with no damper, or take the damper out.

 

price is right

http://www.alexsparts.com/valve-spri...rf-hyd-roller/

 

Da ghetto grind

Wasn't going to mention that one, but yeah

 

The 906 Vortecs I have were good safely to only a max lift of .470, then I had them machined to take a bigger cam.

 

Mine are 906s and they measured out to exactly .470 out of the box. I put LS1 springs in with Comp 787-16 retainers and instantly got .532 without any machine work.

 

Since you have the heads off, take them back the shop and have the guides cut and shortened.

 

This.

 

Really? I thought the Vortecs were limited by the valve guides not the spring coil bind...

 

The comp retainers are smaller and add more clearance which allows for more lift

 

Beehives... basic ones, but the principle works the same.

 

Done this several times and again just recently. Beehive style springs (plenty of choices with spring rate and installed height to suit) with the appropriate retainers. What you will probably find though, is that an .050" offset valve lock is required to get the proper installed spring height. No machine work needed on guides or spring pockets.
If the heads have been modified for a larger spring (which in my humble opinion is the wrong way to go) then all bets are off.

 

So you think beehives are a better method than a cheaper conventional spring? I can see some reasons you might think that, but I'd love to hear your take on it. Personally I am ambivalent, just about whichever is cheaper to facilitate your cam choice.

Also... Are you saying stock Vortecs have an installed height of 1.7, and you used offset locks to get it to 1.75?

 

First the springs:
Valvesprings: Single wire with damper 1.235” O.D., 0.875” I.D. 75-pound seat pressure @ 1.700” installed height Coil-bind @ 1.150”
As for the beehives:
There is an excellent write up of a Spintron test comparing the 26918 Comp springs to the Comp 987. The Beehive spring proves far and away the best choice on many levels.
As an example, even though the 987 delivers 12% more seat and open pressure, the 26918 ran to more than 1000 rpm more before losing control.
Retainers are lighter, the spring has better science. Works for me. In fact besides having the 918s on my now retired Vortecs, I also installed them on my new RHS 170cc Pro Torkers. Both sets of heads required the .050" offset lock to achiever 1.800" installed height. The RHS are spot on while the OEM are slightly short.

 

Thats what I thought. I knew the beehive style spring was a superior design... but it's 3 times the cost. Didn't expect it to actually perform better with numbers that look more reasonable, though. That's interesting to know.

 

[QUOTE=InfernalVortex;5225212... but it's 3 times the cost. .[/QUOTE]

Only until you float a valve into piston or you find that your horsepower output is down because the spring can't control the valve and you're bouncing off the seat.

 

Run the beehive springs, retainers and locks pending they are right for your cam. It will cost just as much as machining the heads to take the recommended small diameter springs but the beehives are superior in design.

I have a set of 906 heads at the machine shop as we speak getting the following:
26918-16 valve springs
787-16 retainers
648-16 locks (might have to be changed for a lock with some offset)
Order that stuff through CNC Motorsports and you'd save like $50-60 over Summit!

I went with GMP screw in studs. Other than that stuff my heads are just getting set up for screw in studs, hot tanked and a valve job.