finished sy build
- Thread starter sytydvr
- Start date
sytydvr said:
Nice build, nice to hear the board was a help....valve float is generally caused by weak springs or revving a motor over its intended RPM range, I'm not sure how oil pressure is going to cause the valves to float? If there is too much crankcase pressure (air) I could see it happening but how would that occur exactly? especially when your under boost? Maybe 2cold has seen this happen? Our motors are two very different beasts but I get 90PSI from my 3 stage dry sump pump and pumps harder the more RPMS I push, currently I'm spinning to 6500RPMS and I know my oiling is good as it pushes its way out of the breather on the valve cover. Remember oil is the life blood of the motor, most motors fail due to poor oiling, spun bearings etc...I would definately keep an eye on it but you should be OK...being oily is gooder :wink:
sytydvr
New member
awesome 
well the previous engine suffered 2 spun crank bearings.... so i decided to go with high press/ high vol to prevent any disaster.... oddfire thanks 4 your response and input.... definately helped out
hey falco u mentioned custom chipping would u think ultimate will suffice i was going to put it on my own christmas shopping list ....
thanks again
sy#682
ty#2351
well the previous engine suffered 2 spun crank bearings.... so i decided to go with high press/ high vol to prevent any disaster.... oddfire thanks 4 your response and input.... definately helped outhey falco u mentioned custom chipping would u think ultimate will suffice i was going to put it on my own christmas shopping list ....
thanks again
sy#682
ty#2351
I too rebuild my engine with a high flow/high pressure pump, i had the option to replce the spring but did not know about high pressure cause floating valves. After reading these posts i got a little concern about my engine.
So i asked a friend at work that competion drag races a SBC about floating valves with roller lifters at high rpm, here is his respons:
If you plan of reving your engine past 6000 rpm, yes it will float valves and they will hit pistons if you don't have enough clearence. It happen to him ones and he installed solid lifters after that, but he is reving his SBC to 8-9000 rpm. He told me not to worry if i stay at normal shift rpm = 4-5000 rpm.
You can eliminate some or most of the floating by installing harder valve springs. When i have some spare time over i will drop my pan and replace the spring in my oilpump just to be sure.
On my stock oil pressure gauge i have about 40psi on idle and 60-65 on the highway. I'm going to install a mec gauge later on in life both for oil pressure and coolant temp.
So i asked a friend at work that competion drag races a SBC about floating valves with roller lifters at high rpm, here is his respons:
If you plan of reving your engine past 6000 rpm, yes it will float valves and they will hit pistons if you don't have enough clearence. It happen to him ones and he installed solid lifters after that, but he is reving his SBC to 8-9000 rpm. He told me not to worry if i stay at normal shift rpm = 4-5000 rpm.
You can eliminate some or most of the floating by installing harder valve springs. When i have some spare time over i will drop my pan and replace the spring in my oilpump just to be sure.
On my stock oil pressure gauge i have about 40psi on idle and 60-65 on the highway. I'm going to install a mec gauge later on in life both for oil pressure and coolant temp.
2cold said:
Let see if i can explain this easy, with to much oilpressure inside the lifter it's no longer hydralic. The oilpressure is higher then the valvespring pressure, you have no play in the lifter (it's like a solid lifter) causing the valve to stay open all the time. I hope you can understand what i'm talking about
[quote="OddfireV6
I'm not sure how oil pressure is going to cause the valves to float?
:[/quote]
[quote="OddfireV6
I'm not sure how oil pressure is going to cause the valves to float?
:[/quote]
2cold
New member
just a 6 said:
just a 6, you explained exactly what I was talking about. Thanks for bailing me out with the technical explanation. I was just brushing up on my valve train theorey about to formulate an accurate response for sytydvr and you got it right. I didn't wanna word something wrong and screw everyone up.
Falco
Donating Member
sytydvr said:
I'd say no. The ultimate is a great product, but it was not tunned for aftermarket cams. There is a cam and head version of the 50's, but you have no 50's (no need for them till you upgrade to a larger turbo) . Even if you had 50's you still should do some custom tuning because the head and cam version was aimed to combos with CompCams and Vortec heads...
It will run, maybe will run just as well as with a stock cam, but won't be optimal.
Later,
myclone
Donating Member
Too much oil press cannot cause "valve float"(uless you have 500psi of oil press). Valve float is caused by over revving the engine to the point that the valve springs dont keep the valve train components in contact with their respective mating component.
In example: take a baseball and bat out in the front yard. The bat represents a cam lobe and the ball represents a valve, lifter, push rod, and spring. Take the bat and whack the baseball straight up in the air. Now, wait for the ball to come back down to the perfect spot for you to whack it straight up again. Repeat a few times just for the hell of it.
What you just did was simulate what the valve train does in a normal(non valve floating) situation. Well sorta...
Now, do the same thing but as soon as the ball leaves the bat on its upward journey take another 10 swings with the bat in the same manner as the initial one. Didnt do you a lot of good did it? The ball was still up in the air while you were swinging like a mad man.
Same thing happens with the cam and lifter. At low RPM the cam whacks(for lack of better words) the valve train "up" when the opening ramp of the lobe begins. The valve train continues its journey "up" until its at the nose of the cam lobe. This would be when the above mentioned ball would have traveled to its max height and moments from starting back down. Next the lifter starts down the back side ramp of the lobe of the cam. This is the downward journey of the ball. It gets whacked back up again as the cam lobe comes around again. This happens several times per second at, say, 5kRPM.
You could make the bat ball thing happen VERY fast if you attached a spring to the ball and anchored it to the ground. That way you wouldnt have to wait for gravity to bring the ball back down to you. Thats what valve springs do. They make sure the valve comes back to earth(cam lobe in this case actually) so the lifter("base ball") will be there for the cam lobe to whack again.
Now immagine for a moment that you are physically able to swing the bat fast enough to swing a few times while the ball is still in the air even with the above mentioned spring attached. Doesnt do you a lot of good to be able to swing that bat like a wild man while the spring is stretched out and the ball is still up in the air does it? Whats the solution? Stronger spring connected to the ball and the earth to bring it back quicker so you dont "waste" any swings. Same thing with the valve train.. If you want to spin the engine to high RPM you have to have a strong enough spring to keep the valve from "floating" in mid air while the cam spins worthlessly under it(bat/ball/you swinging like a mad man scenerio). Hence the term "valve float" due to the valve train just "floating" in mid air while the cam is down below swinging its little heart out for no good reason.
Lot more to it than that but hopefully you get the idea. If not get yourself a bat and ball and go out in the front yard for some batting practice.
In example: take a baseball and bat out in the front yard. The bat represents a cam lobe and the ball represents a valve, lifter, push rod, and spring. Take the bat and whack the baseball straight up in the air. Now, wait for the ball to come back down to the perfect spot for you to whack it straight up again. Repeat a few times just for the hell of it.
What you just did was simulate what the valve train does in a normal(non valve floating) situation. Well sorta...
Now, do the same thing but as soon as the ball leaves the bat on its upward journey take another 10 swings with the bat in the same manner as the initial one. Didnt do you a lot of good did it? The ball was still up in the air while you were swinging like a mad man.
Same thing happens with the cam and lifter. At low RPM the cam whacks(for lack of better words) the valve train "up" when the opening ramp of the lobe begins. The valve train continues its journey "up" until its at the nose of the cam lobe. This would be when the above mentioned ball would have traveled to its max height and moments from starting back down. Next the lifter starts down the back side ramp of the lobe of the cam. This is the downward journey of the ball. It gets whacked back up again as the cam lobe comes around again. This happens several times per second at, say, 5kRPM.
You could make the bat ball thing happen VERY fast if you attached a spring to the ball and anchored it to the ground. That way you wouldnt have to wait for gravity to bring the ball back down to you. Thats what valve springs do. They make sure the valve comes back to earth(cam lobe in this case actually) so the lifter("base ball") will be there for the cam lobe to whack again.
Now immagine for a moment that you are physically able to swing the bat fast enough to swing a few times while the ball is still in the air even with the above mentioned spring attached. Doesnt do you a lot of good to be able to swing that bat like a wild man while the spring is stretched out and the ball is still up in the air does it? Whats the solution? Stronger spring connected to the ball and the earth to bring it back quicker so you dont "waste" any swings. Same thing with the valve train.. If you want to spin the engine to high RPM you have to have a strong enough spring to keep the valve from "floating" in mid air while the cam spins worthlessly under it(bat/ball/you swinging like a mad man scenerio). Hence the term "valve float" due to the valve train just "floating" in mid air while the cam is down below swinging its little heart out for no good reason.
Lot more to it than that but hopefully you get the idea. If not get yourself a bat and ball and go out in the front yard for some batting practice.
2cold
New member
Myclone your right about the valve float caused by RPM, but your wrong if you think that oil pressure cant open the valve with a hydraulic lifter. When the valves are closed stock springs are only putting about 80lbs of pressure on the spring so your 500lb example isn't really right becuase even the pressure of the spring at open height wouldn't be that high.
myclone
Donating Member
2cold said:
Oil pressure can hold the valve off the seat if the pressure his high enough(ei: high RPM). Thats called "lifter pump up". Valve float and lifter pump up are two different things happening.
Lifter pump up happens at RPM, like valve float, but what happens is the plunger in the lifter that is compressed when the lash is set is pushed up against its retaining ring due to high oil pressure(like when the bypasses are blocked off). This is no big deal, for the most part, when the cam is not on the base circle but when it is on the base circle the valve never fully seats(closes). This causes reversion if the intake is held slightly off the seat or blows the cyl pressure out the exhaust if its the exh valve thats slightly open. While all this is happening none of the valve train components ever lose contact with each other which is one of the key differences between the two.
Valve float on the other hand is caused by over revving to the point the valve springs can no longer keep all the valve train parts tightly mated. There is actually a "gap" or "space" between the valve, rocker arm, push rod, or lifter.. Or all the above while valve float is happening. Kinda "bangs" the valve train componenets against one another as the valve spring tries to keep everything togeather while the cam lobe whacks the bottom of the lifter which launches the valve train over and over.
Lastly. Neither problem is good but an engine can actually live a somewhat long life if exposed to lifter pump up although power will be down while its going on. On the other hand "floating" the valves on a regular basis will destroy part/all of the valve train a lot quicker.
sytydvr
New member
i have done a whole new buildup on my sy and... i now need a custom chip..... when it comes to tunning, fixing, pretty much anything to a car im good at but chips i have no clue any local socal syty fellaws can help out with this..... willing to pay$$$$$$$$$$$ i want to keep my stock computer..
thanks again
sy#682
ty#2351
any local socal syty fellaws can help out with this..... willing to pay$$$$$$$$$$$ i want to keep my stock computer..thanks again
sy#682
ty#2351