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View Full Version : Max Lift with Vortec Heads

street3285
06-30-2010, 10:47 PM
I recently bought some vortec heads for the small block I am going to build. I have always read that the max lift is .480" with the stock valve springs. Is this true? Or is this only if running a roller cam. I am going to be using a hydraulic flat tappet.
ElkyZO6
07-01-2010, 07:06 AM
That is correct for stock springs. They are a smaller diameter spring too. Beehive springs or machine the heads for regular ones are your only option.
street3285
07-01-2010, 08:14 AM
Is that the max using a roller cam? Or can I get away with a .500" lift cam since I am going to a hyd. flat tappet?
ElkyZO6
07-01-2010, 09:10 AM
I'm not sure, but I would change them to be safe.
street3285
07-01-2010, 09:29 AM
It is close, but do you think I will be able to get away using this cam with the stock springs?

http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=108&sb=2

What is the deal with shimming the valve springs? Or is that just not the right way to do things?
ElkyZO6
07-01-2010, 11:29 AM
The stock springs won't be able to control the valve at those rpm's aka valve float. Read this on shimming the springs. http://www.supercarsunlimited.com/info/tech/springs/springs.htm

If I was you I would run these springs. http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=26981-16&Category_Code=SBCNEWValves

What rocker arms are you going to use?
I'm running the same heads on my El Camino, but with a smaller cam so I've been down this road before.
street3285
07-01-2010, 11:52 AM
Appreciate all the help.

So you are saying, because that cam will be putting the springs at their max potential, I might experience valve float at higher RPM's? Thanks for the help, just trying to understand all this and learn.

I will be using the factory 1.5 arms for now. I am kind of on a budget, and want to cut back where I can. Eventually, I will change them out to roller rockers. I do plan on leaving the self-aligning rockers with factory press-in studs.
ElkyZO6
07-01-2010, 12:04 PM
The rocker studs will not stay at that lift. You can drill a small hole in the boss on the head and drive a rollpin in. I had screw in studs put in mine.
street3285
07-01-2010, 01:20 PM
I am not looking to race the truck, or rev it to 6000.... I was hoping I ccould maybe get away with leaving the stock springs, but it sounds I might have to change those out too.

Or maybe step down the cam to this one...
http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=107&sb=2
Basically, I am looking for a real aggressive lumpy idle, but still be streetable. Is there another cam you can maybe recommend? I don't mind trading off a little horsepower for this, as it won't be a race truck.

Is a machine shop needed to change over to screw-in studs? Or is this something I can do in the garage?
ElkyZO6
07-01-2010, 02:23 PM
I would back down to something like this if you really want to run stock springs and studs.
http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=85&sb=2

Screw in studs will have to be done by a machine shop.
SR71
07-06-2010, 07:29 AM
I have the small thumpr flat tappet cam in my mild 350 with rhs 1.94/1.5 vortecs. it is all the cam you can stand in a daily driver. it is even kind of a pain in the ass with my 6 spd and 3.73's because it wants to buck the car at light load cruising. it runs and sounds great, but I would not recommend the larger thumprs unless you have 400+ cubes.
street3285
07-07-2010, 04:11 PM
How is the idle with that cam?
What do you have done to your heads? Are they completely stock?

The truck will have a 700R4, and eventually 3:73's.
SR71
07-07-2010, 08:17 PM
the idle is pretty radical...along the lines of a 305 magnum from comp.

heads are aftermarket vortecs from racing head service in memphis. they flow a nice bit more than stock and have the correct comp springs and screw in studs/guideplates as delivered. compression is 9.5:1.

it will work fine with an auto. if you use a lock up converter, you will have to experiment with lock up points.
street3285
07-09-2010, 09:59 AM
Anybody know of a good machine shop in SoCal, where I can have the machine work done needed to install screw-in studs, and non-beehive springs?
ElkyZO6
07-09-2010, 11:20 AM
You can use LS6 springs and comp's 787 retainers as a cheaper alternative.
street3285
07-09-2010, 04:14 PM
Sweet.... I will have to check that out. Maybe get some exact part numbers from you.

If that is the case, then all I will need to do is switch over to studs. I am assuming I can still use the self-aligning rockers I have.
SR71
07-09-2010, 05:31 PM
Sweet.... I will have to check that out. Maybe get some exact part numbers from you.

If that is the case, then all I will need to do is switch over to studs. I am assuming I can still use the self-aligning rockers I have.

as long as you do not use guide plates. guide plates and self aligning rockers do not mix.