Don Terrill’s Speed-Talk

Ford Y block lifters, also found in 223-6 and 134/172, 4 cyl.

Aluminum bushings with oil passages for lifter oiling, in the lifter holes and overhead oilers for the valve covers. Mocked up, using a CC .904 lifter cam. Everything fits, with lift to spare.

Since the title is,

duration @ .050"/ .200"

. Let me ask another question. Is there any reason to believe that a solid lifter cam, with the same .050 & .200 duration as well as lift, would perform any different than a roller lifter cam?

The 1" solid lifter 260*, appears to be, right in between the CC, RC & TK, Sprint Car roller lobe duration @ .200, with the 1" having slightly more lift (.007 lobe), based on the .050 & .200 duration.

frnkeore wrote: ↑Sun Oct 25, 2020 12:40 pm Ford Y block lifters, also found in 223-6 and 134/172, 4 cyl.

Aluminum bushings with oil passages for lifter oiling, in the lifter holes and overhead oilers for the valve covers. Mocked up, using a CC .904 lifter cam. Everything fits, with lift to spare.

Stock lifters? What spring pressures do you plan to run? what oil?

Yes, stock Y block lifters, Manely 625# springs and 30 wt, 3600 ppm zink for break end. Tool steel lifters if, the combo shows promise and they show any signs of wear.

dan miller wrote: ↑Mon Aug 23, 2010 11:51 pm Could someone please ‘splain what can be discerned by comparing two cams with the same duration @ .050", but different @ .200"?

For instance, consider a cam, 236 @ .050", 150 @ .200", .340" lift, 108 lsa, as compared to a similar cam, but 152 @ .200".

Does a degree @ .200" make more or less difference than a degree @ .050"? I’d guess more. If so, how much? Does 2 degrees @ .050 have about the same impact as 1 degree @ .200"?

Thanks, Danny

IF the lobe lifts are about the same it would be sort of a way to compare the actual area of the lobes to one another.
That leaves a whole lot more which could and probably would be different to make those lobes act differently.

Using duration at 0.050" lift is like evaluating a fine wine by biting the cork. It tells you very little about what
is in the bottle.

Cam profiles are very complicated shapes not easily reducible to single data points.

A proper starting point would be a lift curve plotted in 1 degree increments, from base circle to max lift.

The curves can be overlaid for examination or the angle areas calculated for comparison.
We can compare the blowdown period, IVC, ramp slopes, and overlap areas.

Next the derivatives should be calculated to determine velocity and acceleration values for each lobe.
This is extremely useful when evaluating used camshafts. And to determine minimum lifter diameters.

You can stare at a wedding cake all day and never know what is in it.

then you can run a simulation to see which the engine prefers for optimisation of VE at a specific rpm range if it’s not immediately apparent

frnkeore wrote: ↑Sat Oct 24, 2020 5:17 pm This is a cam that I'm having Howards make for me, using 1" mushroom lifters, in a SBF, with 280 cfm heads and four 4412's on the Holley 300-275 TR. The intake lobe is for a 1" lifter and the Exhaust lobe is a .904 lobe.

I would love to see that intake, do you have any photos of it?

There's too many other variables, to make an accurate assumption, based off of .50" and .200" durations.
You would have to assume the lash heights were the same, and that the velocity curves were close.
I just designed 2 lobes, changing the shape, and the lash ramp by .003".
Both had the same lobe lift, and were the same at .050", and .200", but cam "A" was bigger above .200", and "B" was bigger below .050"(4 degrees bigger at the lash point.
When you adjust for the .003" difference in lash ramps, "B" is the same as "A" at .250" and .300", but 2-4 degrees bigger everywhere else.

A few weeks ago, I designed a lobe to replace a design by someone else for a steady-state engine. The shapes were completely different
They both had the same lash, and the same lobe lift(.377"). Looking at .050" and .200" would tell you nothing about these two designs.
Profile "A"
192 @.006"
173 @.020"
153 @.050"
103 @.200'
68 @.300"

Profile "b"
193 @.006"
178 @.020"
160 @.050"
104 @.200'
66 @.300"

Mike, this is the am that I'm having made.

Oldie but Goodie, Miss Ya Danny.

dfree383 wrote: ↑Fri Nov 20, 2020 7:03 pm Oldie but Goodie, Miss Ya Danny.

No Kidding!!

frnkeore wrote: ↑Fri Nov 20, 2020 5:32 pm Mike, this is the am that I'm having made.

What does the area represent and how is it figured?
Thx.

fastblackracing wrote: ↑Fri Nov 20, 2020 11:55 pm

frnkeore wrote: ↑Fri Nov 20, 2020 5:32 pm Mike, this is the am that I'm having made.

What does the area represent and how is it figured?
Thx.

If your asking me, I do not know. Mike would be the one that would have to answer that.

fastblackracing wrote: ↑Fri Nov 20, 2020 11:55 pm

frnkeore wrote: ↑Fri Nov 20, 2020 5:32 pm Mike, this is the am that I'm having made.

What does the area represent and how is it figured?
Thx.

The area is the area under the lifter raise curve. It is broke down / shown from a given start to stop lift point.

Stan