MILD THUNDER

iTrader: (3)

I've recently read some articles on valvetrain setups, and some words from a highly respected builder who's spent an enormous amount of time on spintrons. One of the things he said, while generalizing, was that, for the longest valve train life, use a spring with the least amount of pressure, that will keep the valvetrain stable.

It makes sense to me, that as spring pressures increase, the loads on the cams, lifters, pushrods, rockers, increase. On my engines, I have been running 165psi on the seat, and 460ish open, for a long time now. They were setup that way for around 200 hours, and then I tore down in 2010, and everything looked good, so I went back with that setup, as the builder freshening my heads, agreed that was a good setup. Its been working since 2010 that way spinning 5800rpm, hyd roller, 6lbs of boost. On the dyno, we spun to 6400, without signs of float. I have the morel 4603 lifters, which call for 160-180psi of seat pressure, and continous operation to 6600RPM. Their 5045 lifters, which call for 200-225 seat, 550-575 open, supposedly can withstand 7000RPM. Which is great, but what is the penalty for running 5045 lifters, with 200/225 to 550/575psi, on an engine that will never exceed say 6000-6200RPM?

Now, I have seen other guys, running in the neighborhood, of 200-220, and 550ish over the nose on hydraulic rollers. I've never got a good answer from anyone running that setup, as far as how long their valvetrain has lasted? 100 hours, 200 hours, 300 hours, etc?

For me, I sometimes do lots of idling. Its not uncommon to have to idle for 15, 20 minutes sometimes, or even more.

I certainly know and understand the repercussions of an unstable valvetrain, lofting the lifters, and so on, when insuffucient spring pressures are installed. But, what are the repercussions, of having too much spring pressure, for the application?

When paging thru catalogs of basic bbc hyd roller cams, crane, crower, lunati, isky, howards, comp etc, I've never seen any of them recommend 200/500+ spring pressures for a bbc hyd roller. I'd like to think these companies have done a little R&D on this topic?

For the guys running higher spring pressures, what kind of life have you seen from your valvetrains?

BenPerfected

Our valve springs when new using solid Jessel lifters were 240 lbs on the seat....more like 220 with some hours. It you set your valve train up on the Spintron, you can get great valve train life with next to no valve train maintenance. Today we have 90+ hrs with many at 6000 + RPM. We only check the lash after each season. For us, a season is about 4 PR's around western Lake Erie to the Islands. The most we ever have to adjust is just a few lifters .001-.002. We will likely check the lash for 2015 tomorrow night....just to be safe. Where I am going with this is, are you sure you want to use hydraulic lifters?

Cole2534

iTrader: (1)

If you assume valve actuation forces are moot, more or less cancelled by each other as the cam spins, then I only see 2 downsides to excessive spring forces.

1) component strain. Lifters, push rods, rockers are all under extra stress for no real gain.

2) spring size. To get those higher rates the spring has to get larger in one dimension for sure, wire diameter. You can put that added material into length or OD.

This assumes good valves, keepers, valve seats, etc...solely the spring is in question.

SB

iTrader: (1)

More spring psi a lot of times means more mass. To control more mass,,,,is more tough.

However, cam lobe, rocker ratio, mass of other valvetrain parts - valves ! / retainers / etc , oil temperature, engine rpms, and etc,etc,etc effects every thing to.

Beenperfected - thats great !

Bawana

Joe, there is a video on youtube that was of a seminar put on by.. i believe crower. They talked in depth about valve train setups. They went on to say that the biggest mistake by engine builders is they use to much spring pressure. The guy said to use the least amount of seat and open pressure to make it work. He went on to say that more pressure then needed not only shortened life, but also robed power.

MER Performance

Joe,
I have read your "thread", I can only speak for myself as a engine builder. Max rpm for the Morel, hyd lifter you are mentioning with a set pressure of 165-170, I only use, up to 6k rpm either forced or naturally aspirated. I have used the lifter from Scorpion, .700 wheel in a 8.1 496 whipple turning 6k pushing 900 hp. I wouldn't say; its all focused on rpm. Lobe design, valve train mass, psi on back side of intake valve and if your using stud mounted rockers or shaft mounted. Pushrod diameter, resulting in deflection, is another important factor.
You can also have valve spring issues at lower rpms, with frequencies set-up from other issues. ( someone else can touch on this subject ) Harmonics from the crankshaft are transferred, from the crankshaft by using a timing chain, into the cam shaft also. In a perfect world, much of what you are saying is true. It would be nice, if everyone of one of us had a spin-tron, we could take our cam, lifters, push rods rocker arms and simulate that setup and rpm.
If you are running, boost on the backside of the intake valve, its going to be very hard to see, what that valve is doing, when its coming back onto the valve seat, can it bounce, yes. Will you see that on the dyno, most likely; not. You can float, your valves at high rpm, and not see, anything as far as decreased power or in extreme cases hear the engine flatten out or pop. You can see it in BSFC, to what point of slight to extreme, can't answer; that. My target rpms, are always, spot on within a 100 - 200 rpms.
Using a HI REV, lifter has its, time and place, I see it used for the guy; that never wants to lash valves. Set-up, is set as I stated above. I really prefer; a tight lash, solid roller over the hydraulic, HI REV. Valve spring set-up, goes the same way. I see it as not always by a set rule, but by, application and type of boat you are running, flat across the water or big water, with constant, increases in acceleration and deceleration in rpms. That holds true if you are racing or running in a poker run or decide to hit the ocean and hammer some waves.
Circle track, drag racing, and boats all run in different environments, and rpm conditions. I'm not disagreeing; with you, what I stated is true, for what I look at in determining, how I do my set up, for different applications. The camshaft, will tell you a story of whats going on after the fact, upon inspection, 8620 billet material and wheel contact, may not always tell the story. So, we may add more spring pressure.

Black Baja

iTrader: (2)

Joe, I can't give you an answer to your question because I didn't run the 5045 morels long enough before I changed directions with the motor. But as SB was hitting on. As the performance of the engine/ valvtrain increases so does the maintenance. When the cam gets more aggressive the need for more spring pressure is needed. A .600" cam doesn't need the amount of spring pressure that a .800" cam needs. The difference of .200" is a lot more work that the valvetrain has to do. With that said it only makes sense that the valvetrain with more movement wears out faster. With all things the same and a stable valvetrain it also would make sense that the "over sprung" valvetrain wouldn't last as long as the "correctly sprung" setup. I know of a builder down this way that swears by the 5045 but limited travel (whatever that part # is). He uses a lot of spring pressure .700" cams and has many trouble free engines in the field with lots of hours on them. One particular engine is a fellow OSOr's that is reluctant to post the build up due to all the bickering that goes on. It's a shame. Nice build lots of power with a boutique 4150 carb and trouble free build...

BenPerfected

MER,
You don't have to own a Spintron machine to test with one. You just have to have a customer that thinks $2000+ in Spintron testing is good/great value on a $10-40k engine. As you know, this technology is why the NASCAR SBC engines can live at 10,000+ RPM.

MILD THUNDER

iTrader: (3)

Good info guys.

I guess my question was initially about a concern of the lifter needle lifespan, with high spring pressures, in a pleasure application, that has to idle alot. So, was looking for guys to chime in with things like

"hey, i have a hyd roller 700HP 540 with 280 hours on it, running 220/550 spring pressures".

I guess it boils down to too many variables. The average bbc marine engine around here, has a valvetrain mass that is probably always somewhat similar by design. But, then we get into different lobe profiles, that can dictate the spring requirements needed. We all like to make more power with more aggressive lobes, but there must be a tradeoff somewhere. While a stock GM truck engine may go 300k miles on the original lifters, with gobs of idle time, obviously a custom, agressive lobe with mucho spring pressures, would not be able to do so.

I suppose in design theory, while valve lift is a contributing factor, rocker ratio can be as well. A cam that has more lobe lift with less rocker ratio, vs less lobe lift, more rocker ratio, can still net the same valve lift. But, it seems from what I have read about, is that the latter of the two, may provide less side loading of the lifter, allow a larger base circle cam. Seems in some applications, the aggressiveness of the lobe, can be tamed down, to take some load off the lifter, allow lighter spring pressure, but only if the cam is designed to be used, with the higher ratio rocker.

Its also interesting to know, that lifter wheel diameter, has an effect on things as well. A cam designed for a .700 wheel, should use a .700 wheel. A cam designed for a .750 wheel, should use a .750 wheel. A cam designed for an 800 wheel, should use an 810 wheel. While it has an effect on the timing/acceleration, apparently it can also be a cause of valvetrain instability. That chit is way above my head.

I guess it boils down to, is there is always gonna be a compromise. The guys who do this stuff day in, day out, really have it tough. Everybody wants more power on the dyno, but everybody also wants a long lasting valvetrain. So, if you do a long lasting mild lobe setup, the engine makes less power, and customer isnt happy. But, if you do an aggressive setup, the customer is happy at dyno day, but may not be happy 100 hours down the road. But, by that time, any failures will more than likely be blamed on something else. Like lifter issues, oiling issues, setup issues, etc. Which may or may not have been the cause of failure.

The more and more I am learning this valvetrain stuff, really is steering me towards solid roller profiles on my next build.

ezstriper

cam lift/ramp are going to be factors on the needed spring pressures, then you would need a lifter that would handle that, but yes the less pressure you can run will help them live