So I'm deciding based on pricing whether or not to cam my L31 before I drop it in.

I have settled on http://www.summitracing.com/parts/CRO-00409/ this cam by Crower. This motor will be sitting in front of the factory T5 so I'm not gunning for any radical numbers. Also, this should set within what is possible for a factory Vortec head.

I need a little information though. If I swap for this cam, am I going to NEED to replace the factory springs? I have no idea how flimsy they are. I was looking at the 918 beehives but they seem to be single springs. Dont I need doubles for a roller application?

Little insight would be much appreciated.

 

How old are your stock springs?
Probably worth replacing due to age alone

Spring selection is based on the spring rated pressure and max lift to suit cam type; not the spring config
Plenty of singles out there that handle way more lift than your cam

 

The stock vortec springs are extremely weak and should be replaced. If i remember correctly they are 170lbs compressed. The beehive springs are stock on LS series engines and are a great choice for a vortec upgrade. They provide more spring pressure, greater stability at a higher RPM, and more spring travel without coil bind.

The problem your going to run into though is the valve stem oil seal. The retainers might hit the seals with 470 lift. Some vortec heads have plenty of clearance and some dont, they vary quite a bit in castings. The simple fix for this is to switch to umbrella style seals while you have the valve springs off. That should give you enough clearance to run up to 550 if i remember correctly, but PLENTY of room for the cam you want to run.

With that being said have you considered the GM LT4 Hotcam? Its a deal at just over $200 and has some proven hp/tq numbers that look really good with vortec heads.

Hope this helps

 

Yes you ABSOULTELY MUST replace the stock springs. They are EVEN FLIMSIER than most stock springs. They are barely adequate to control the valves when used with the weenie stock Vortec cam; they are entirely inadequate for an aggressive modern performance cam. The valves will surely float.

That looks like a decent cam choice to me.

 

Yes, change the springs!

Retainer to Guide clearance will be the biggest issue with that lift which may send you looking for a cam with < .460 lift. Your options are machine the guides down, run umbrella seals, use +.050 locks, or buy expensive springs & special retainers which will allow that clearance.

I'm trying to figure which go to with myself as I have a set of Vortecs and a cam on the way with .485 lift on the exhaust just putting me over the edge. I'll probably machine the guides down to be safe and run a stock diameter spring like the comp 981 or the recommended spring for the cam.

 

https://www.thirdgen.org/forums/post...681-post1.html

 

That is an amazingly informative post! DOes that mean that I can use those LS6 springs on completely stock vortec heads? no machining neccessary?

 

Yes, the LS6 springs fit vortec L31 heads with no machining. You do have to use the correct retainers and locks though.

 

Wouldn't it be theoretically possible to have more clearance for lift by just using the LS6 springs and comp retainers alone WITHOUT using the umbrella seals? Could I use the stock valve seals with this setup and still have enough for ~.500 lift? Also, which locks would be a good option if you cannot use the stock ones?