wannafbody

iTrader: (2)

I wonder if cam lobe profile also plays a role? It would seem that softer lobes would be easier on rockers.

Johnny_M

it is the lift that is the issue. Ramp speed and duration doesn't really play a big roll in scrubbing the stems.

Ls7colorado

iTrader: (3)

why wouldnt it?? it your moving the rocker faster it would would have more resistance and more wear.....

Johnny_M

the problem with the stock rocker is that it goes over center with too much lift and locks up. This is the main cause of stem wear. Too much spring pressure is also an issue.

00pooterSS

iTrader: (40)

Doesn't really work that way

If it did high hp motors that rev faster would wear out bearings faster since they rev faster

Everything rides on a film of oil that separates the metal from touching. You're not gonna see wear whether the rocker is pushed open slowly or quickly

Also, the higher the rpm the quicker the rocker is actuated. If lifting it "faster" caused wear people that revved higher would be wiping out rockers and valves and we don't see that.

wannafbody

iTrader: (2)

I was under the impression that with aggressive ramps and high rpm that the roller lifter can bounce off the lobe which I think would in turn increase wear at the rocker tip.

Johnny_M

the roller lifter shouldn't bounce off the lobe. If it does then higher spring pressure is required.

Bob570

Interesting thread, the design of the Smith Brothers kit had me worried about this exact thing, so I went with the CHE kit when I did my cam about 8000 miles ago. I plan on doing heads this spring so I'll have to check them out. Hopefully they look ok.

cula8r

iTrader: (2)

Just wondering......... maybe this is the reason why GM has kept the bulk of their camshafts in crate motors and production engines with lifts under .600"?

Bspeck82

No....high lift rates make for a more aggressive can lobe. You have a steeper travel over the same distance on the lobe. This creates more power (if the head supports it) but requires pricier springs, lifters, pushrod etc. Keep the lift low, save millions of dollars and the car will not have as peaky of a torque curve, therefore driving a little smoother. Lobe acceleration and jerk intensity can also cause havoc on low budget valvetrain. The ls7s (lifters) ls6 (rockers) are great for what they are and many take them to .630 and up but gm engineers had a reason to not do it. They would tell you you are crazy for making 800whp on the stock bottom end reliably but we do it. Not me but others do.....

G Atsma

I seriously doubt here is ANY mass production engine with .600 or more lift. Not due to engineering issues, just that it is not needed. Camaros and Mustangs have over 450HP available, a historic high. All achievable with lifts far under .600. The LS3 has lifts of .550/.525. No more is needed. And they live forever that way.

wannafbody

iTrader: (2)

Need vs want. We want more lift for more hp.

G Atsma

Right. So then you buy/make the necessary pieces that will live with high lifts.
The factory has no need for such high lifts, so don't depend on them for that kind of capability.
They only needed pieces that would see lifts UP TO .600, so that's what we get.
Anything above that, roll your own or use the aftermarket.

Ls7colorado

iTrader: (3)

Were do you see high RPM engines that dont have accelerated valve train wear?

dreadpirateroberts

iTrader: (1)

That video isn't too surprising in terms of what happened to the bushings, but I expected more mileage out of them. He had roughly 6,000 miles.

I wonder what lift he was running?

Guess it's time to throw these out and go for a different design when the time comes.

dreadpirateroberts

iTrader: (1)

I think they can design around the material limitations. We use lifts that high because we aren't designing the whole engine from scratch. They can do computer aided head port and cc chamver design and make the engine perform how they wish with a relatively milder cam and valvetrain that will last 200,000 miles.

00pooterSS

iTrader: (40)

All of the modified engines I have had over 20+ years. My first build had a 8100 rev limit. No wear on the valve train over years of daily driving. All my LS and LT engines have the rev limiter turned up. No wear anywhere or failures other than valve spings, which I have seen many times on stock engines too. All of my friends that have turned up rev limiters that haven't had failures. Tons of guys on here going years on modded setups...


But we were are talking about the valve tip and rocker tip on the post you quoted.
Where are all these threads where people have worn out valves stem tips and rocker tips?

And really, most people are not wiping out valve train components. Thousands of stock engines have wiped out lifters, springs, and rocker trunions too so that kinda disputes your theory that higher power and higher rpm is the cause. Where are all the guys wiping out bottom end bearings from higher horsepower and higher rpm (there's increased load and rpm on the bottom end too)? And I'm not talking about when someone over revs and stretches the rod bolts and causes a bearing to spin. I'm talking when setup right and running for years without issues.

00pooterSS

iTrader: (40)

That is a concern when running high ramp rates, higher rpm, having springs that aren't strong enough to control it.. But it's an issue with the valve spring controlling the valve train and the reason why we upgrade/run the correct valve springs for the combo. You can have that same scenario with a stock cam if you turn up the rev limiter and the springs can't handle it. I broke 8 of 16 valve springs doing that on my SS lol. It didn't like going to 7000 every day on 140k mile valve springs. Put in LS6 springs and that fixed the issues.


If you haven't look up some videos on valve float and you'll see things bouncing and vibrating and what causes all the destruction. There's some pretty cool high speed film videos of it happening on youtube

Ls7colorado

iTrader: (3)

Not saying its enough to cause it to wear out fast enough to notice.. But with anything, you have to apply more pressure to more an object fast vs moving it slow. More pressure is more stress/heat/wear.... And you cant tell me that 10,000 rpm slinging a piston and rod around isnt putting more wear on bearings vs 5,000rpm, and the same goes for opening and closing a valve. How much more??? I dont know lol

tech@WS6store

iTrader: (2)

The tsp rockers are way better than any aluminum. Also they are "investment cast" just like stock. Not stamped steel. Not your fault for not knowing that.
They have an infinite fatigue life vs limited in comparison to aluminum and are much lighter over the valve PLUS you can use a shorter pushrod for less flex and they can use a CHE bronze bushing also.

Investment casting is where a wax positive is made of an object. Then casting put around it. Then the liquid metal is poured into the mold melting out the wax. That is how the structure can be so strong yet intricate with its trussing. Super strong and durable and lower price to manufacture so it translates over to the customer.

As far as the shops.
One was an engine machine shop. The other is a straight automotive repair that work on any type/brand of vehicle but do see ALOT of chevy trucks from 99-16. They also see quite a few stock spring failures and burned valves. Which I have referenced before.

Been sick so catching up. Any other questions i missed? Or references?

Our interlocking bearing design will hold up better than stock. You have to LITERALLY destroy the race to get the rollers out and they are not needles like stock either.