[68WarDog]

I'm aware we're putting solid roller lifters on hydraulic roller cam profiles, but has anyone did the opposite? I have a solid roller cam I would like to try hydraulic roller lifters on. I'm aware of changing out the heavy sr springs. Or are the sr cam profiles too harsh for a hydraulic profile to follow?

[tom s]

The cam makers say no.Solid roller cams are designed with a lash setting.Hyd rollers are setup with zero lash.When going the other way you use a small lash on the hyd roller cams.Contact Mike Jones at Jones cams if you need more info.Tom

[Steve C.]

https://www.motortrend.com/how-to/so...Dup%20problems.

https://www.onallcylinders.com/2021/...ic-roller-cam/


.

[Stan Weiss]

Originally Posted by 68WarDog

I'm aware we're putting solid roller lifters on hydraulic roller cam profiles, but has anyone did the opposite? I have a solid roller cam I would like to try hydraulic roller lifters on. I'm aware of changing out the heavy sr springs. Or are the sr cam profiles too harsh for a hydraulic profile to follow?

The quick answer is no. But it is possible it might work on a very tight lash solid roller cam. What does the cam card call for hot lash?

Stan

[68WarDog]

Originally Posted by Stan Weiss

The quick answer is no. But it is possible it might work on a very tight lash solid roller cam. What does the cam card call for hot lash?

Stan

Hot lash is .026, but I usually run .020 on street.

[Jay S]

Appears like you have an older Ultradyne or Lunati roller. R79 and R80 profiles. You could run hydraulic roller lifters on it with no issues other than having a bunch of extra seat timing. Hydraulic lifters would make it very soggy at lower RPMs, it will probably have about 320* of seat timing at .006” with hydraulic lifters on it. If I am correct and it is a Ultradyne, it is a .0175” lash ramp design and has pretty long lash ramps. Really way long too work well with HR’s on it. It is a relatively gentle street roller. 917s comp springs are extremely heavy springs for that grind with SR lifters.

[Stan Weiss]

I only have a couple of cam files. This is a Lunati UD Solid Roller 271 @ 0.050"

CAM_______Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea____ICL
_________0.00600____53.63_|__99.40_|_333.04_|__40. 99_|_112.89_<<_Where_Hydraulic_Rated
_________0.01000____49.22_|__92.96_|_322.18_|__40. 95_|_111.87
_________0.01333____46.06_|__88.68_|_314.75_|__40. 91_|_111.31_<<_Duration_@_0.020"_Lash
_________0.01733____42.84_|__84.48_|_307.32_|__40. 85_|_110.82_<<_Duration_@_0.026"_Lash
_________0.02000____40.96_|__82.08_|_303.04_|__40. 81_|_110.56
_________0.04000____30.52_|__69.37_|_279.90_|__40. 47_|_109.43
_________0.05000____26.48_|__64.76_|_271.25_|__40. 27_|_109.14
_________0.10000____10.92_|__48.17_|_239.09_|__39. 10_|_108.63
_________0.15000____-0.99_|__36.11_|_215.12_|__37.68_|_108.55
_________0.20000___-11.80_|__25.37_|_193.57_|__35.77_|_108.59
_________0.25000___-22.59_|__14.72_|_172.13_|__33.30_|_108.66
_________0.30000___-34.18_|___3.33_|_149.15_|__30.13_|_108.75
_________0.35000___-47.44_|__-9.76_|_122.80_|__25.89_|_108.84
_________0.40000___-64.18_|_-26.32_|__89.50_|__19.49_|_108.93
_________0.45000___-93.61_|_-55.55_|__30.84_|___7.04_|_109.03

Stan

[ponjohn]

Don't the solid roller ramps accelerate too quickly and compress the HY roller lifter?

[Jay S]

ponjohn, for sure the spring pressure required for a lot of SR cams really limits the possibilities of HR lifters on them. A tight lash street solid roller that does not require a lot of spring pressure would very likely work well. That 276 SR Ultradyne isn’t probably to bad of a candidate, except it is not a tight lash set up. The other type of SR profile that some have used with decent results on a SR profile with HR lifters is a high ratio rocker SR profile that lacks some negative acceleration over the nose of the cam, they use more moderate rocker ratios with it. Harold Brookshire said on a forum he had used HR lifters on some SR profiles. From what I recall, his thoughts were: Why would you want too? And: If you do it, you better know what your doing.


I think I was very likely pretty high on what I estimated the seat timing would be on that 276, 284 UD cam. The intensity at the lower lifts for the 276&284 Ultradyne looks similar to that cam Stan posted. If they are both .0175” ramp designs they likely are similar on the low lift accelerations. Looked to me like Stan’s example was likely a .0175” lash ramp like a .3883” UD. That would put the UD 276, 284 at 305* intake and 313* exhaust at .006”. It might be slightly more than that. But I think you could run HR lifter on it if you wanted.

Here is a Ultradyne HR profile for comparison
300* @ 006”
278*@ .020”
245*@ .050”
168*@ .200”
.3823” lobe lift

Versus that .3883” solid roller
305*@.006”. Estimated??
276*@.020”
243*@ 050”
162*@ .200”
.3883” lobe lift

The SR actually has less acceleration up to .2” lift than the HR profile, but above .2”the .3883” SR likely has a bit more negative acceleration over the nose than the .3823”HR I listed. You can hardly tell the difference between the SR and HR looking at those numbers.

[Jay S]

Originally Posted by Jay S

Here is a Ultradyne HR profile for comparison
300* @ 006”
278*@ .020”
245*@ .050”
168*@ .200”
.3823” lobe lift

Versus that .3883” solid roller
305*@.006”. Estimated??
276*@.020”
243*@ 050”
162*@ .200”
.3883” lobe lift

The SR actually has less acceleration up to .2” lift than the HR profile, but above .2”the .3883” SR likely has a bit more negative acceleration over the nose than the .3823”HR I listed. You can hardly tell the difference between the SR and HR looking at those numbers.

I should add some to this post…Even though these two profiles look kind of close, the Ultradyne’s mechanical lifter design ramp (what I called the .0175” lash ramp) is on the closing side of the cam. The opening side is a “no pulse” design ramp. Basically means the differences in low lift durations of the .3823HR and the .3883SR cam, are mostly put onto the closing side of the .3883”SR profile, essentially the HR’s having no lash will be retarding the cam timing quite a bit on the SR. If the cam is pretty small and wants less advance, the engine may very well like it. Starting with an existing set up, your best off tightening the lash on the mechanical set up before trying hydrualics. It will give you a pretty good idea of how it will work out and whether or not the engine is going to like the change to HR’s. Good or bad..

[Stan Weiss]

I see Jay found a real lobe. I modified the real lobe data I posted (271.25 @ 0.050 / 0.45654 lobe lift) above to have a max 0.3883 lobe lift and 243 @ 0.050". Note this also modifies the lash ramp.

CAM_______Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea____ICL
_________0.00600____41.19_|__81.95_|_303.14_|__32. 20_|_110.38
_________0.01000____36.68_|__75.57_|_292.24_|__32. 15_|_109.44
_________0.02000____28.64_|__65.18_|_273.82_|__32. 01_|_108.27
_________0.04000____18.43_|__53.02_|_251.44_|__31. 68_|_107.29
_________0.05000____14.43_|__48.58_|_243.00_|__31. 50_|_107.07
_________0.10000____-0.99_|__32.44_|_211.45_|__30.30_|_106.71
_________0.15000___-13.16_|__20.24_|_187.08_|__28.79_|_106.70
_________0.20000___-24.73_|___8.80_|_164.07_|__26.67_|_106.76
_________0.25000___-37.01_|__-3.28_|_139.71_|__23.95_|_106.86
_________0.30000___-51.28_|_-17.36_|_111.36_|__20.00_|_106.96
_________0.35000___-70.34_|_-36.23_|__73.43_|__13.82_|_107.06

Stan