Don Terrill’s Speed-Talk

Belgian1979 wrote:what i said in the other thread about shockloads

Not to mention the massive surface speed changes as the roller acels and decels up and down the lobe, a bit hard to compare that to a uni joint or crank bearing !

CamKing wrote: As for running bushing lifters in a marine application,
Here's one of our "marine" customers, that's been running our bushing lifters for the last 2 seasons. Zero problems. 2 championships
https://www.youtube.com/watch?v=Zuo5p-K ... e=youtu.be

Nice, thats definetly one motorsport where you dont want to have an 'oh shit' moment and back off the throttle mid turn!

Also in all of this its interesting to note thay Iskys advertising for EZX's says low friction, and , increased horsepower. But compared to what? Not that im bagging them as i like and use them.

[1] Roller brgs in a lifter... are compared to a U joint...or a wheel brg....because they are ALL roller brgs. Just different sizes & shapes....

[2] Hammering loads. A hyd lifter bleeds down, certainly at low rpm, so when it seats there is clearance in the valve train & is subject to some amount of hammer. If the lifter floats at higher rpms, then at some point it will crash down on the lobe, giving new meaning to the word hammer....

[3] H-D roller brg big ends [ & other brands ]. The rods [ & brgs ] have to stop the piston as it comes to a stop at TDC. At high rpms at the end of the exhaust stroke, this load assumes several hundred pounds that has to be absorbed by the rod brgs. If that is not a hammer like load, then I don't know what is....

Geoff2 wrote:[1] Roller brgs in a lifter... are compared to a U joint...or a wheel brg....because they are ALL roller brgs. Just different sizes & shapes....

[2] Hammering loads. A hyd lifter bleeds down, certainly at low rpm, so when it seats there is clearance in the valve train & is subject to some amount of hammer. If the lifter floats at higher rpms, then at some point it will crash down on the lobe, giving new meaning to the word hammer....

[3] H-D roller brg big ends [ & other brands ]. The rods [ & brgs ] have to stop the piston as it comes to a stop at TDC. At high rpms at the end of the exhaust stroke, this load assumes several hundred pounds that has to be absorbed by the rod brgs. If that is not a hammer like load, then I don't know what is....

You are really comparing Apple's to bananas in an effort to support your views.

And for the guys preaching a rev kit as the holy grail of fixes, while they may reduce the rapid speed change during separation, they do very little to reduce the shock, as there is still separation/lash in the system, and the resulting shock loads are still transmitted to the needle bearing via the axle.
The only way to really reduce it, or soften the blow, is to eliminate the system separation all together. IE hydraulic lifters.....

Mike Jones, please be nice to me, I am old, besides, I have a gas oven.

And for what's it's worth, I am a successful drag racer with many wins and many years of experience. Simply an old country boy sharing his thoughts and experiences.

This is one of my projects http://classracer.com/classforum/showthread.php?t=54442

Warp Speed wrote:And for the guys preaching a rev kit as the holy grail of fixes, while they may reduce the rapid speed change during separation, they do very little to reduce the shock, as there is still separation/lash in the system, and the resulting shock loads are still transmitted to the needle bearing via the axle.
The only way to really reduce it, or soften the blow, is to eliminate the system separation all together. IE hydraulic lifters.....

Warp, a rev kit is only the holy grail of keeping the roller at lobe speed with an SR until an rpm is reached that allows the lifter mass to overcome the rev kit spring force. My point with the rev kit (should be renamed SR Street Kit for this purpose) is to keep that wheel on the lobe at idle and lower rpms, and it does that quite well.
Any shock loads that the valvetrain sees are of course felt by every moving part no matter what and the shock loads, at least the largest not considering valve float are only as harsh as the lash ramps allow.
Possibly the best of both worlds at least for a streeter would be a short travel hydro lifter on an SR lobe that has been tweeked to allow for the difference in said lifters characteristics.
May as well just run a big girly roller!

cjperformance wrote:

Warp Speed wrote:And for the guys preaching a rev kit as the holy grail of fixes, while they may reduce the rapid speed change during separation, they do very little to reduce the shock, as there is still separation/lash in the system, and the resulting shock loads are still transmitted to the needle bearing via the axle.
The only way to really reduce it, or soften the blow, is to eliminate the system separation all together. IE hydraulic lifters.....

Warp, a rev kit is only the holy grail of keeping the roller at lobe speed with an SR until an rpm is reached that allows the lifter mass to overcome the rev kit spring force. My point with the rev kit (should be renamed SR Street Kit for this purpose) is to keep that wheel on the lobe at idle and lower rpms, and it does that quite well.
Any shock loads that the valvetrain sees are of course felt by every moving part no matter what and the shock loads, at least the largest not considering valve float are only as harsh as the lash ramps allow.
Possibly the best of both worlds at least for a streeter would be a short travel hydro lifter on an SR lobe that has been tweeked to allow for the difference in said lifters characteristics.
May as well just run a big girly roller!

At idle and low speed, what is the rpm of the roller wheel, and how much does this rpm change as it rolls around the lobe, assuming constant contact?
At this rpm, with solid roller lash, is the inertia weight of the wheel itself enough to cause a rapid change above surface/lobe speed in the short time cam is on the base circle? Or are you saying the roller actually stops?
Is that what we're trying to cure with a rev kit or?

I do know one thing, that engines with revkits and needle bearing lifters, live longer than the ones without.

The automatic lash (compensation) mechanism need not be in the lifter... "hydraulic lifter"
In fact that is a bad place for it. It need not be hydraulic. It need not be in the lifter.

Hydraulic lifters were just a simple affordable adaption to existing OHV pushrod engines at the time for passenger cars. This works very well right up to the operation point where it does not.

There are better ways of doing this.

If valvetrain separation at lash causes roller lifter bearing shock then the camshaft lobes should be designed to reduce that lash ramp shock (or lack of a lash ramp shock)
Valvetrain running noise level is a good indicator of the mechanical lash shock on the opening side. And the shock of the valve seating on the closing side.

If you want less shock, design it into the cam lobe lash ramp. (length of and rate of)
A longer lash ramp on the lobe allows for more lash setting variance caused by engine temp change.
If less shock is better then a quieter running valvetrain is better.

The needed slightly more extended seat to seat valve event duration for this as a cam lobe design parameter can be offset by a slightly higher engine compression ratio. The keyword is "slightly".

Warp Speed wrote:...At idle and low speed, what is the rpm of the roller wheel, and how much does this rpm change as it rolls around the lobe, assuming constant contact?..

If we assume a 0.800" roller, a 1.0" cam base circle, a 0.400" lobe lift and a 1,000 RPM idle (500 cam RPM) the roller speed on the BC would be 500 x 1.00/0.80 or 625 RPM. At the top of the lobe it would be 875 RPM. Sounds a lot less drastic that the high RPM case: 5,000 & 7,000 respectively @ 8,000 crank RPM...

turdwilly wrote:Perhaps the benefit of pressurized oiling through the needle bearings of the lifter is not so much from the standpoint of lubrication, but of cooling?

Correct.

Warpspeed,
Lots of criticism of me by you, but no answers or objective opposing views. Just criticism. Any idiot can do that. There must be an agenda that I am missing...