I've got some 906 casting vortec heads coming in tomorrow or thursday with about 20k on them. I don't have the cash, nor the need, to upgrade the springs or anything on them. Just plan on using them as-is.

My question is what what cam should I limit myself to with these? I'm not sure what cylinder volume is (or if it matter) but from the looks of it, it appears the block has not been decked, the cylinders are bored 040 over, and the pistons are slightly dished with valve reliefs. Probably looking to buy an Edelbrock Vortec RPM too.

I'm looking for something the has a very noticible lumpy idle as it will just be a weekend cruiser, street mainly - no highway. I have a 4.56 posi that I will probably put in there, but may go with a 3.73 if i can find one. Right now it has 2.41 or something (ouch). It's coming out!

I've tried to figure out cam selection on my own, but I'm having a hard time deciphering what each number means in real world terms. Would hate to get something that wouldn't work.

I know people ask these questions all the time and probably don't listen to the advice given. I just honestly don't know what to look for. Thanks in advance.

Stock Vortec springs aren't worth crap over about 4K RPMs (valve float). You MUST replace them in a performance application. These were OE on trucks, and meant for low end torque, not high RPM horsepower. Thus the poor flow characteristics over about .500. As for lift, you'll have to measure to be sure, but stock it's right around .460 - .470.

Since they are still on the bench, it's best to check to see how much lift they will take unmodified. I've heard claims between .450 and .470 lift. Take all the valvesprings off, then check each valve to make sure, with seal installed. And yes replace those springs! They are only about 80 psi on the seat http://www.nastyz28.com/ubb/wink.gif

Ok, so are the springs something I could do myself with a little patience and no experience in such things? Or should I look into taking them to a machine shop? What would something like that run?

What springs should I look into getting?

Thanks.

Changing springs on the bench is as easy as pie- Rent a compressor from Autozone, compress each spring and slide out the locks. Compress new spring, put it on, slide in locks and decompress - a monkey could do it!

You'll want to match your new springs to the cam you choose - most cam MFGs suggest a spring for each cam. Just make sure they fit the sppring pockets. Vortecs have a 1.29 pocket, IIRC but don't quote me on that -

Oh ok, great. Sounds easy http://www.nastyz28.com/ubb/smile.gif

But now back to the question on the cam. What is a streetable yet noticible cam to look for with my setup?

Do some research on the Comp Cams XE268- Could be a good choice. I'm sure others would disagree- Personally, I run the XE262, and am very happy with it. It doesn't "hit" at idle though - Pretty smooth.

I will post this again.....

"Here's some gold for you from Gary Penn of GM Performance Parts. I have several of his posts saved from a techboard somewhere on the net - I think it might be chevytalk, or chevelletalk or something like that.
Here is one of his posts that directly answer’s some of your queries. BTW - if you use Vortec heads you'll be flat amazed at how much power these things make for a truck head. I run them on a 413-cube small block and have nothing but positive comments for them.
Let's proceed directly to Gary's very detailed and insightful comments:

"Two years ago we undertook an exhaustive (no pun intended) study of the Vortec head in numerous modified states with different valve sizes, throat cuts, valve jobs, port mods, guide mods, etc. We used up about 10 heads, numerous valves, and about $50,000 worth of labor. The study generated 100+ pages of flow and swirl data, which I have at my desk.
Here is the short version. Out of the box, .480” valve lift, 350-400 HP dependant on the CR, cam, ring seal, oil control, blah, blah, blah.
More than .480” lift cut the guides down to clear the retainers.
Straight mill up to .060” safely, .080” with low CR of 10 to 1 or less. 0.100” is living on borrowed time. Always use flat top or dished pistons to enhance flame travel and intake swirl.
Angle mill up to 1 degree (about .110” off the exhaust side, .000” off intake side) safely for about 12 to 1 CR with flat pistons with little valve relief. Angle mill to 2 degrees (about .200” off exhaust side) if you like to live on the edge, it has been done.
Larger valves increase flow, chamber mods not needed, trade off between shrouded verses unshrouded valves not worth the decrease in laminar flow and swirl.
Throat cutting behind larger valves compliments the larger valves. Open the throat to the seat then remove the edge left by the cutter in the port.
Blend the seats into the chamber, you don't want an edge here to disrupt flow and create turbulence.
"Bowl blend" and shortened guide in port also improves flow. Taper and blend the iron boss.
Minumal porting increases flow, too much increase in port size or loss of the benefits of the shape of the stock port will decrease efficiency.
Vortec heads (and most others) like straight stemmed valves. Undercut valves create unwanted turbulence and a decrease in intake charge velocity (they add volume (slowing the gases) to the overall "port" volume just behind the valve where max velocity is required.)
Generally speaking, Vortec's stall at between .500” and .550” valve lift. This is where flow actually begins to decrease. But their true strength is low lift flow which gives more area under the total flow curve. And if you think about it how long are your valves at peak lift? They spend much more time at .400” and below, where the Vortec’s outperform most other heads. This combined with high velocity, lack of turbulence and superior combustion chamber design are where the Vortec’s stand out.
Unported, with all the other tricks in place, the Vortec’s will flow about 235-240 CFM at .500” I and 165-170 cfm at .500” E, on a 4" bore at 28" H2O, with clay radiused port opening. With some careful porting there is another 5-10 CFM or so to be had. But again the low lift numbers are unsurpassed at .100”, .200”, .300”, etc. lift. For example the Vortec’s flow as much air at .400” as .500” and no 23 degree head that I'm aware of can match them at .200”-.300” lift for the combination of flow and swirl. Even the Fast Burn head can't touch them at low lift, it's ports are too big (flow is similar, swirl is less), it does of course out perform them at lift over .500”.
Unported Vortec’s with the "tricks" can produce 500 HP on well built, high CR, drag race short block. 425-450 HP is more realistic for a killer street engine running on pump gas."

And....

"Per Dirt R. You will love the Vortecs on a 400. Incredible torque and overall power. I bowl ported mine, and did some minor work in the runners. At a minimum, fully bowl work the exhausts, as they are the only real weak point on the Vortecs. You can use the stock intake and exhaust valves (which are back-cut from the factory) and the stock first-rate factory 3-angle valve grind. I came within a whisker of an 11-second pass in the heat of July running Vortecs on drag radials with a cheap Crane Blazer 234/244 hyd. cam. I ground off 3/16" off the bottoms of the factory retainers for retainer to guide clearance, and used Crane stock diameter valve springs."

pdq67

If you are looking for a cam, with a choppy idle, then go with something more radical that the xe268. I'm sorry but I don't know the exact numbers for other came, but something equivalent to the xe274 may be what you are looking for. I am definatly looking to go bigger once my car gets back on the road.

sidenote: I have the GMPP casting of the Vortec Performer RPM intake for sale.

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Just some SLO ISH
350 HO "deluxe" Crate
4.10 gears, Vigilante 3000 stall converter, 200r4, CC XE268, Holley 3310 750cfm carb, Performer RPM intake.
14.12 @ 97.47 with 9.1 1/8
Best 1/8 8.8 @ 74

i was gonna get the xe274 it has lower lobe seperation so it should give a lopy sound, they have a sound clip of the xe278 on comp cams website. its not got much more lift than the 274

I have the XE274 and it does not have a loppy idle.Its actually smooth compare the the smaller cam I removed.

[This message has been edited by cattmann1 (edited April 03, 2005).]

<font face="Arial,Verdana" size="2">Originally posted by slmmr75:
sidenote: I have the GMPP casting of the Vortec Performer RPM intake for sale.

</font>

Interested!

<font face="Arial,Verdana" size="2">Originally posted by cattmann1:
I have the XE274 and it does not have a loppy idle.Its actually smooth compare the the smaller cam I removed.

[This message has been edited by cattmann1 (edited April 03, 2005).]</font>

I'd have to say somethings wrong with your tuning. I run the XE274 and all I ever hear is "Damn, what kind of cam you running?" I'm very pleased with the "choppy" idle, not to mention the awesome torque.

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Objects In Mirror Are LOSING

<font face="Arial,Verdana" size="2">Originally posted by GoldenOne7710:
I'd have to say somethings wrong with your tuning. I run the XE274 and all I ever hear is "Damn, what kind of cam you running?" I'm very pleased with the "choppy" idle, not to mention the awesome torque.

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I was thinking the same thing when I read this. I have the XE274 in my 406sbc and the idle is very noticeable.

Thanks for the replys guys. I've been looking at the XE274 as well.

I am running a vortec set up on a 355 and total timing around 32 degrees .Car works excellent and pulls a 12.90 at 106 in the 1/4. First thing I noticed was the smooth running compared to the Ertel cam I removed.It had a .447 lift with a 290,290 Duration and a 223 @.050.This cam sounded very nice.

[This message has been edited by cattmann1 (edited April 04, 2005).]