TZFBird

I am planning on building up a 327 with Vortec heads and a Comp Cams XE274H
LSA: 110
Lift: .487/.490
Dur@.050": 230/236

I am going to be buying some new vortec heads. The power peaks at 5500 with an estimated 350hp. I am thinking I can get away with the press-in studs, but I am wondering what to do about the springs. Can fresh stock springs do the .490 lift, or should I go with a higher quality spring? If so, could someone suggest some springs? I can't afford some really high quality stuff here, I am just looking for the cheapest spring that is better than factory, but will solve this problem.

Thanks

alohamike

your cam has more lift than recommended for Vortec heads. On the other hand, what are you doing with the engine? going to work or competition drag racing? If it's your daily driver and you want to race on the weekends for fun, get a cam you can live with. 230 is a lot of duration for a daily driver especially for a 327. You'll be gasping off the line and your gas mileage will suck. You'd be better off with something in the 210-220 range and not as much lift so you don't tear up your heads (springs, studs, lifters, rockers) faster than you can afford to replace them. If you stay under .450" lift, you can use the stock springs that come on the Vortec heads for years to come. And, you'll have a much more driveable machine that will still put you back in your seat and keep the Mustangs at bay.
Oh, and save some money for a decent rear gear ratio. You've probably got a standard 2.73 open gear set and you're going to want something in the 3.23-3.73 range to take advantage of the car's new power.
Good luck whatever you decide.

RB83L69

DO NOT attempt to run that combo on stock Vortec heads. The springs suck, they're barely adequate for the .400" peanut stick they use sin those motors in the first place; they will cause a great deal of trouble with a super-aggressive cam, which that one definitely is. IMHO if you put anything beyond a 929 cam (.390"/.410") in it, the springs are inadequate.

But, an even bigger issue is the heads themselves. The valve guides are so tall that the retainers will hit them at around .480" of lift. To run more lift than that, you will have to get the guides milled down.

Remember, those are NOT performance heads, no matter what the flow numbers are. They are replacement truck heads, and they come out of their box equipped as such. The secret to success with them is to take advantage of their strengths which are good flow at relatively low cam lifts and low price, and stay away from their weakness, which is the total lack of performance prep such as pull-out studs, no guide clearance, crap springs, etc.

Use a XE268 and the 981 springs that are supposed to go with it, and you'll go plenty fast.

TZFBird

Think I could get away with .454 max? The XE256H runs that much. Would the factory springs handle that, or would I still have to go with some aftermarket higher quality springs for that cam? This is pretty much a daily driver. I can't believe the difference between a roller cam and regular flat-tappet lifters. almost a 50hp difference. I should just keep my 305 instead of going to an old 327. The lack of cubes would be made up for by the roller cam/lifters.

alohamike

I think you can make that cam work although I agree with RB that the XE268 would be a great cam for that engine and the Vortec heads. The GM crate engine, HT383 uses a cam with .431/.451 lift and also uses the Vortec heads, and it's really designed to go into a truck. The usual GM warranty is 3yrs, 30,000 miles, so the factory has faith in the springs and the rocker studs for longevity. If you're going for daily use, go less wild with the cam. The Vortec heads will make more power with almost any cam you can put into the block because they flow so well.

TZFBird

Ok, I gave it some thought, but am I still going to have to get the heads milled to accept the XE268 that you guys are suggesting? If I can get away with just using the heads rightout of the box, I would probably go with that. If I am sacrificing the 20-30hp from the cam, I would like to be able to save the $ I would have spent on the machining. I think you said I should swap springs, so I will still need that. If the heads still have to be milled, it's no biggy.

tyler

alohamike

RB and I do disagree about the springs. I believe you can use the stock ones for what you're planning on. As I pointed out, GM puts the Vortec's on its crate 383 with a high lift cam (.431/.451) and gives it a warranty. If you're going to spend a lot of time at the track or run the engine at high rpms on a regular basis, you should consider the new springs, but if your mostly driving to work or school and racing occasionally, the strockers are fine. Besides, springs can be replaced with the engine in the car should the day come when you need to change them. As for milling the heads, the stock chambers are 64cc. You may want to mill them .020 and bring them down to 60cc. That'll give you a decent compression ratio, probably 9.8:1 or better, but I'm not sure of that.

TZFBird

I'm going to keep stock compression. I don't want to be buying expencive fuel as well as using more with the larger cam.