max cam lift on stock vortec heads????

[tommie]

what is the max cam lift that can be used with stock vortec heads?

i have heard everything from .420 to .450

what lift cams have people used with stock vortec heads?

i am unsure of what cam to buy at this point,
was looking at an eldebrock performer camshaft with .420 lift on the intake and .442 on the exhaust (i believe)

just tring to get some opinions before i buy

thanks
tommie
70 chev swb (all torn down right now)

[bigjimzlll]

from what I hear, I would'nt go with the edelbrock grind..there are better grinds available..as far as lift goes..on page 42 of the new chevy hi-performance magazine says"The stock springs will only accommodate around 0.420 inch of lift."
Jim

[Project1970]

I've got a Comp Cams 260H right now, with 0.440" lift intake/exhaust. Not terribly exciting...I like the look of the XE256H, though. .447" intake, .454" exhaust.

[tommie]

project1970,

are you running the stock valve springs on your heads?

im not looking for any radical cam,

just want a good running truck, not looking to win any races.

tommie

[Project1970]

Box-stock from Scoggin Dickey, without any of their available mods.

The 260H isn't a bad cam, but the XE256H kicks the crap out of it - it's a nice dual-pattern, with LOTS of low-end. It brings the power peak down a few RPM's from the 260H, but there's more power, and with my mostly stock setup, Desktop Dyno claims I'll be pushing near 400lb/ft until 4000RPM without even putting headers on! The 260H needs a little time to get out of the hole...

[twelveflat]

Keep in mind that the stock Vortec springs have very low seat pressures also. I believe they are about 90#'s. I would definately upgrade to a better spring even with a mild cam like the 260H. As said before the XE series cams are even better due to the increased ramp speed of the cam. This leads to other problems though. With a light spring pressure such as those on the Vortecs, the valve will have a tendency to "bounce" on the seat and float at higher RPM. You should be safe with a cam near the .485 - .500 lift area but typically you will have more problems with the formentioned problems than coil bind. If you don't want to step up to a better spring, you can stick with the milder 260H or similar grind and use between a .030 to .060 shim under the spring to increase seat pressure approx 10 to 15#'s. Maybe more info than you wanted. Just my 2 cents.

[Project1970]

What kind of RPMs are we talking about, though? Mine seems fine through 5500RPM, aside from lacking the guts to keep moving the beast any faster, that is. :P

[twelveflat]

With the cam that you are running right now I'd say you are on the threshold. You obviously haven't had valve float yet but I'd say you're on borrowed time beyond that rpm. Of course its a truck why would it need to go past 5500 rpm anyway. I'm only saying that problems are less likely to occur with the 260H than the XE256 with the stock springs.

[chevjayfsd]

.450 is about maxing them out...I had a .454 on my stock vortecs.. but then i flattend the cam so i had them upgraded to the z28 springs and now they are good for about .520 in exhaust lift.. i bought the XE by comp and it lifts 469 at exhaust. If i were you I would go ahead and upgrade the springs before you consider the cam.. it is very cheap..they sell the z28 springs 16 in a box for about 39.00 or 89.00 cant remember...
Jason

[Project1970]

Originally posted by chevjayfsd
.450 is about maxing them out...I had a .454 on my stock vortecs.. but then i flattend the cam so i had them upgraded to the z28 springs and now they are good for about .520 in exhaust lift.. i bought the XE by comp and it lifts 469 at exhaust. If i were you I would go ahead and upgrade the springs before you consider the cam.. it is very cheap..they sell the z28 springs 16 in a box for about 39.00 or 89.00 cant remember...
Jason

Yeah, but don't you need to machine the heads for them to fit?

I'll probably be tearing the bottom end apart by the time I put a cam into it anyway...it is nearly 130,000 miles and 32 years old...

[chevjayfsd]

yes you do have to mill .110 off of the valve guide...While we had that done we got screw in studs so they won't do any lifting on their own...We have the best machine guy in town doing it...all for about 180, so if all you want to do is get bigger springs on it shouldnt cost anymore than 120
Jason

[Purs]

I've got a Lunati with nearly the same specs as the XE256H, .447" intake, .454" exhaust and it's got TONS of power! And yes I upgraded my springs as well. Hey chevjayfsd, are you talking about Ed's Machine Shop?

[bigjimzlll]

get the new issur of chevy hiperformance..it shows how to mill the valve guides and seats for new springs, with a hand drill!!!

[chevjayfsd]

No but they are in a close second...I am talking about Clyde's machine and hobbies...on Oak..He is slow but he does a great job
He works on most of the sprint cars and modified that race at Abilene Speedway.

Thanks
Jason

[Jesse 67 c-10]

I got a XE256 for my 327 with vortechs, havn't put it in yet, I also have the recomended valve springs and retainers, anyone know if I'll need to get the guides machined down? also, screw in studs are a good idea I know but are they must have nessasary? Give me a worst case if say a stud pulls out. If I have to machine the guides I'll get the studs done too but if not I'd like to leave the heads on the truck! Thanks!
Jesse

[chevjayfsd]

Jesse,

I was running the 256H with my stock vortecs(with non-screw in studs) I ran the truck for about 5 minutes while my rocker was loose, and Flattened the cam BAADDD!!!

So now I got the Z28 Springs and retainers(which I believe is the reccomended) and a 262H with .462 and .469 and the screw in studs..Havent put it all together yet but i will tell yall results..

I desktop dynoed mine and it said it should be around 361 Hps...But i dont know if that is correct.

I might even send my the 262H back and get the 274H with .487 and .490. But i dont know....

P.s.. If you put the z28 springs in.. yes you will have to get them machined.. I do beleive it is .110 of the valve guide, but maybe not...

If you Have any Questions call Scoggin and Dickey...They gave us all the info we need and more....Or try the Website..

Http://www.SDPC2000.com

Thanks
Jason

[lukecp]

I am planning on upgrading to some Vortec heads this spring or summer. I will proably buy the upgrade kit from Scoggin Dickey (heads, intake, gaskets, bolts, rockers) for $730. They say the heads are good for about .450 lift in stock form. I have a "RV" style cam in my truck, with .420/.443 lift. I'm not planning on swapping cams, i figure that the 270/280 duration will bleed off a little compression so i can run 91 octaine with a 9.7:1 ratio. Would it be a good ideal for me to upgrade to the Vortec kit that has the heads machined for around .480 lift?

[Kid]

By measuring your individual spring pocket, from top of valve guide to underside of an installed valve spring retainer, on the valve that will be used in that position, is the only sure method of knowing exactly how much cam lift you can use on your assy. (you can get by with a 6 " dial caliper) You can not go by someone elses results ( because of machining tolerance accumulation). My personal experiance with my set of vortec heads on a 400 small block, using the stock retainers/locks, I was able to go up to .490 lift at the valve, without interference with the valve guide. (switched to Comp cams springs too), but as I said, you must measure "your" assy. to be sure.. I used the Comp Cam XE 268 and am very pleased with the torque. This cam is some what mild in the 400. Just my 2 cents...