grthrawn

was looking on how to machine my heads and came across this article figured it might be of some use http://www.chevyhiperformance.com/te...ift/index.html

Supervisor42

EXCELLENT ARTICLE!
I don't know why, but they can't resist throwing just one fly into the ointment. (maybe it's just to tick me off)
Everybody that has one of these, raise your hand...
"Y'all be sure and use this $800 tool to check the valve height"

wha hail, I use mine all th' time...
Excellent article, seriously.

five7kid

iTrader: (14)

Summit has a store brand for $40. The most expensive one they carry is $101.69.

They talked about replacing the press-in rocker studs but didn't show anything about that. They're a little off base about screw-in studs either being "guide plates required" or "no guide plates required". That's a screwy way to say it - it's more like the studs that are required depending upon whether or not you do guide plates.

The machinist that did my ZZ3 shortblock told me later he does Vortec heads. I said something about the rocker studs, and he said he bakes the heads so the studs won't pull out - I gave him a screwy look, and he said he's never had one pull out after this baking - said the oven type and temperature are critical to getting it to work right. He's the only person I've ever heard claim that.

sofakingdom

iTrader: (1)

Raises hand...

I have the Comp one, had it for years, can't remember how much I paid for it but seems like it was about $50 or so....

Don't know what I'd do without it sometimes.

Supervisor42

Yeah, I exagerated a bit about the gauge.
Speaking of rocker studs, doing the modification for screw-in studs is more work than the spring pocket/guide boss work they did.
I've always wondered if anything more than pressed-in studs were actually needed for street applications. Most "pulled-out" studs are actually from retainers hitting the guides when people just stick in a high lift cam on a stock engine without measuring anything. I'm not a fan of pinning studs because it makes a mess when a stud breaks. (which pinning probably caused or rocker slot not long enough)
It would be nice if someone could do an experiment of how much pressed-in studs can actually take. Gross lift + over-the-nose spring pressure as in a typical street engine with .525 lift 282 duration.

grthrawn

was lookin online on how to actually machine them to accept larger springs from how they make it sound its easy as hell but im douting it...

Supervisor42

I used the Isky HOLESAW (1.450" OD .70"ID) to do my early model heads. It took about 15 seconds per valve. (15 x 16 = 4 minutes)
5 minutes easy enough for ya'?
(I still have it)
EDIT: It does NOT shorten the valve guide, which is needed for high lift cams.

Supervisor42

The Comp Cams holesaw cuts a 1.440" OD spring pocket and cuts down the guide boss to .630" to fit the Comp Cams spring.
The Isky holesaw cuts it to fit the Isky spring, which is different.
The other Comp Cams cutter, trims down the guide shorter and the top of the guide for the Comp Cams valve stem seal.

Air_Adam

I've seen studs pull out in old '70s stock smogger small blocks, with stock cams and springs. Sometimes it happens, sometimes it doesn't. Heavier springs and/or more lift will make it more likely to happen.

IMO, having screw-in studs installed is worth the extra cost, just because then you know it won't pull out. Its easy to pull out the pressed in studs yourself if you know how - don't even need special tools, and I'm sure thats the bulk of the cost of having a machine shop modify the heads for screw in studs.

I had screw-in studs installed in my 601 heads, and I'm very happy I did. A few weeks after I installed the heads, along with the new cam, springs, and rockers, I had one rocker stud break. Pulled the valve cover, unscrewed the stud and installed a new one - fixed.

Try fixing that with a pressed in stud in less than an hour.

Sonix

iTrader: (1)

Huh, my $20 digital calipers that I use to measure anything below 6" big when I need accuracy as small ~.003" or so, seem to work fine for measuring the valve height. Seems silly to pay $50-$100 on a tool that has only ONE purpose in life, when a generic tool will do the job. Kinda like a hammer or monkey wrench J/K. A few thou on spring height is a drop in the bucket when you've only got .015" shims anyway. (measuring with micrometer, shim with 2x4s eh???)

I'm going to have to read through that article, looks pretty good.

Supervisor42

Thanks Sonix. That was the point I was trying to make.
Besides if we need one, we can always borrow Sofa's .
It is really a good article. Maybe they'll do a follow-up showing the rocker stud rework.

Orr89RocZ

iTrader: (20)

i have calipers and cant measure installed height on heads... you cant get the calipers inside the valve spring area to measure it. i've been trying to figure out how to do it with calipers to avoid getting a valve spring micrometer, and cant get a accurate measurement. i tried sticking something in there to approximate the installed height, and then measure that with the caliper but its not accurate enough.

My measurements could only be accurate to the 0.1 and only somewhat accurate to the .01. I need to be as accurate as possible to the .001. a few thousandths of a inch greatly impacts spring pressure, and its important to have the right pressure for your cam if your revving it over 6000 rpms with a hydraulic roller.


And you can run ls1 style springs like the comp 941's or AFR 8019's and possible AFR 8017 springs or Patriot gold springs which should all fit within the stock pocket of vortec heads. Then just shim them up with .050" shims and .050" offset locks and your now good for .530" lift or so

Supervisor42

I've been lucky so far that the springs are a slightly larger diameter than the retainers. With the valve sprung-up, use the caliper like a depth micrometer and catch the end that the rod sicks out of on the top part of the spring. Then wheel the rod down to the spring pocket. Of course these were non-conical springs.
The idea of the article is to open the spring pockets to allow bigger springs that won't be under as much stress as smaller stiffer springs. This also allows adequate seat pressure without astronomical pressure at high lift.
To quote the author:
"The "Twister Part III" dyno-test shows that the larger 383ci small-block benefited when the valves spent more time off the seat. However, the increased valve lifts would have created a valvetrain stability problem and required stronger valvesprings".

On the subject of lift on stock Vortec heads they state:
"Because these heads are meant to work with a 1.5:1 rocker, their tall valve guides can only handle maximum valve lifts of around 0.420 inch."
Adding .050" should get you about 0.470" with the required safety distance from the seal to the retainer.

Sonix

iTrader: (1)

I have a 3 pack of inside/outside/whatever-the-last-one-is-called old school calipers. I've attached a picture.
Those can measure the pocket up to the retainer easily. You just hold the valve/retainer up and measure it. Then you can measure these cheese-ball 1930's style calipers with your real digital calipers and get something accurate. That's what i've done.
Or you can set something in the spring pocket of known height, and use the "inside" part of your digital calipers. If you're doing this, then you probably have the shims nearby, throw .100" of shim there and measure, then add .100" to it.

I haven't seen valve spring shims in under .015" so any accuracy less than that is almost pointless.

Supervisor42

GREAT! I just spat beer all on my monitorwith that one!

Orr89RocZ

iTrader: (20)

bigger wider springs are heavier and will experience valve float problems before a smaller less wide spring of more pressure. smaller springs are alot more stable at high rpms. And with a roller cam, open spring pressures dont mean much.

I'm gonna have to doubt this claim... many guys will agree that max lift is around .470 with stock heads. Many guys have ran cams with higher lift than .420 but less than .470 on vortec heads. hell the tiny L98 cam would be too much for a stock vortec head but yet many guys run that combo.

Supervisor42

We better get the word out to all of those drag racers, winning races and throwing their money away on them big ol' valve springs then...

Orr89RocZ

iTrader: (20)

Why do you think alot of cylinder head manufacturers are installing smaller diameter springs in their heads? AFR/Patriot/etc. why are all the LSx stuff using smaller springs? LSx cams feature the most aggressive lobes for hydraulic roller lifters available and NO ONE uses typical 1.437 or 1.46 or larger springs.

Look where beehive technology is going. small spring with a design to eliminate resonancy at high rpms.

They are much more superior. Now with solid rollers, obviously they need a larger spring but when talking about hydraulic roller cams, a very aggressive lobe will benefit from a spring with high pressures and these smaller springs they are making now will fit that bill.

The lighter the valvetrain, the easier it is to stabilize. Titanium retainers are used for a reason...for lightweight. Some less aggressive cams wont experience valve float problems, typically old lazy lobe designs. But new technology is making more aggressive lobes to open valves quicker so they are open longer and thus make more power. These lobes like the new XFI lobes are hard to control without heavy spring pressures and when you get big springs, you get more weight and less valvetrain stability. larger diameter springs will reach their resonant frequency much quicker than a smaller diameter spring, which means you need even MORE pressure with a bigger spring to reduce chance of valve float.


now if you are building a motor to only rev to 5500rpms or so, then dont really matter what spring you use. If you trying to make max power out of your setup like i am, revving over 6500rpms with a very aggressive hydraulic roller cam lope with .600 lift, then smaller lighter valvetrain stuff will benefit

grthrawn

then what springs would you recomd on my 355355sbc .100 domed pistons at 11:1 190k psi rod bolts, eagle rods, rebalanced stock crank. was going to but a comp cam 280h magnum cam 280 duration at .470 lift. using 062 casting vortec heads

Orr89RocZ

iTrader: (20)

thats a older grind with .480 lift, 280 advertised duration with 230 at .050". somewhat lazier lobes on it. comp recommends the 981 single springs, and i aggree. it dont take much spring to handle that cam. you can run abit more pressure to be safe from another spring. after awhile due to heat cycling spring will lose some pressure at the seat, so abit more pressure would be nice but not too much more. dont want to wear out the flat tappet lifters. 981 springs setup at 1.700" have 105lbs on the seat. coil bind at 1.150 and giving about .060" of clearance from coil bind leaves max lift at around .490. perfect for that cam with 1.5 rockers

you just gotta make sure you have clearance between retainer and guide. i have heard .470 is max lift on stock vortec castings... so with that cam, you'll be abit over if its true. i'd go with a set of .045 shims and .050" offset locks to raise the spring over the guide for clearance. then your spring pressure will drop alittle to 103 lbs at the seat no big deal