I have vortec heads that are based off the 906 casting. I know the valve size i should use but what kind/size springs should i use?

 

What valve lift do you have?

 

0.465 int./0.488 exh
heres a link to the kind of cam I have http://www.summitracing.com/parts/SUM-1105/
thanks for your help.

 

Generally you pick springs that go with the cam you pick.

It's a kind of iterative process: after you've established a goal, you choose heads that will meet the goal. (I'm assuming you've already got that far) Then you pick a cam that is consistent with the goal, and whose characteristics complement the heads. Then you set the heads up for that cam, with springs and other hardware that support the cam's requirements. If you start out the head process with some knowledge already in hand of roughly what range of cam properties you're going to need to use to get to your pre-set goal, you can order your heads set up for cams in that general range, without having to know exactly what cam it's going to be.

So start at the beginning. What's your goal? How is this car going to be used? (be REALISTIC: no "pie in the sky", no "road racing" if by that you merely mean weaving in and out of traffic during your morning commute, no "700 HP / $400 / 30 mpg" kind of pipe dreams, no "12:1 but I'm going to slap a rear-mount twin-turbo on it some day oh by the way I'm a high school student and my parents won't buy it for me so I'm on a budget", etc.) What's the budget? What heads are they? Any ideas on what cam as yet?

 

let me see if i can fill in some of the blanks. I am building a 383. I am trying to get between 450 and 480 hp out of this engine. This engine is carburetorated. I am using cast iron vortec heads, they are based on the 906 casting (EngineQuest heads). I purchased the heads bare so I just wanted to know what kind of valves springs to use. all the info on my cam is here http://www.summitracing.com/parts/SUM-1105/
thanks

 

Well THAT'S certainly out of left field somewhere. I am forced to confess, I didn't see it coming, AT ALL. I was expecting you'd be trying to put TOO MUCH cam in. I damn near spewed beer all over my monitor when I clicked back on this post and saw that.

Why would you spend all that money on heads and then put THAT under them? That makes no sense. Aren't you looking for PERFORMANCE, and maybe, to get all the benefit out of new heads that they have to offer? NO WAY you'll get any 450 - 480 HP out of THAT, unless it involves about 150 HP of nitrous.

That cam is so lame and mild, just about any springs will work fine. Stock ones like the "Z28" springs you hear about all the time are enough for it. Even stock Vortec springs would probably be OK.

Do yourself a favor... Use some other cam. Something consistent with your goal, instead of a generic copy of a copied generic copied copy of a generic copy of a generic grind from the Civil War days that's WAY too small to begin with for doing what you say you want it to do. Get a modern one, like the Comp XE series or Lunati Voodoo. Something designed in .... oh,,, say,,,, ..... the last 40 years. Leave those generic ones to people who just want something to shove their car from point B to point A and don't care how long it takes.

Then come back and we can talk about springs.

{edit} you must have been adding the cam info as I was making my 1st reply...

 

well im glad that you didnt spew beer all over your monitor. Ill get me a real mans cam thanks for the advice.

 

Just a heads up .
My best of everything 383 has ported TFS 195 heads that flow 280cfm @550 lift
With a 234 / 242 cam and a 750DP it is making around those numbers (dynoed 410RWHP )

 

Thanks: I'm glad too. That sort of thing REALLY makes a mess that's hard to clean up.

What's the rest of the motor and car? pistons especially, and whether it's a roller block, and gears & converter. Do you already have the heads yet, or is it still possible to order them from the mf set up how you want them?

 

Even with that cam (which I'll trust these guys that maybe its small for a 383, all i know is 350s), the lift is still enough that you're going to have to mod the 906 vortecs valve guides. I measured mine closely and my 469 lift is really cutting it close on my safety margin. If you're modding them, then might as well go with a bigger cam. Read this if you havent already http://www.chevyhiperformance.com/ho...458/index.html

 

I have already purchaced the heads. Here is the link http://cgi.ebay.com/ebaymotors/CHEVR...item20b51e582d This is my first engine build as appears evident from my part choices. my pistons are standard summit racing flat tops with 4 valve reliefs (+.030) The car is a 85 berlinetta and I havent even started working on it so gears are a subject that I havent even gotten into yet it isnt a roller block and I havent purchased a stall converter yet