[68WarDog]

I have been doing some research regarding putting hydraulic roller lifters on a solid roller cam. When I Google this it is suggesting tight lash of <.020
I'm aware for the past several years guys have been doing the opposite, installing solid roller lifters on hydraulic roller cams using real tight lash of .004-008. While at our local car cruise, there was a BBF and SBF running this setup. I'd like to give it a try with the UD 243/251@.050 sr assembly that's already in a short block I purchased several months ago. And I'm not convinced of the "morel" sr lifters durability that is in the shortblock. I have been running Crower Hippo on the street for about 15 years, I'd like to try something with less spring pressure. Anyone running this hybrid setup, and if so what is your lash setting and spring pressures?

[lust4speed]

To me lash equals gap. I would think you would still want preload with the hydraulic lifters and I can't think of any reason to run a gap. If anything that would hammer out the circlips on the hydraulic lifters.

[Steve C.]

Another Google search....

"To successfully run hydraulic-roller lifters on a solid-roller profile generally requires that the solid cam profile be a tight-lash grind (under 0.020-inch hot) in the first place, with less than 30 degrees difference between the 0.020- and 0.050-inch duration specs."

https://www.motortrend.com/how-to/hy...echanical-cam/


( Information provided in this post does not represent any endorsement and is offered for general interest only )


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[Jay S]

You won’t be able to run .020” lash and run less spring pressure, because it will take the same spring pressure as it would if you ran SR lifters with .020” lash.

The HR lifter will get beat up worse, they have smaller .7” rollers, not .75” like most SR lifters, and not as heavy built as a SR lifter.

If you want to run quite a bit less spring pressure (mostly less seat pressure) on a SR cam tighten up the lash with SR lifters. If you want to run HR lifters with less seat pressure install the Morel HR lifters then set the lifter preload like you would any other HR cam. It is a small cam, it will run ok like that, mostly just softer lower end power, probably be shorter on top end power also though versus the SR lifters running design lash.

[Jay S]

HR lifters on the SR profiles that work ok are generally higher ratio, high RPM SR profiles. The profiles that work ok are closer to what Steve posted, tend to look more like these:

[Stan Weiss]

This data is from a Cam Dr file of Comp Cams solid roller cam

It has about 32 degrees between 0.020" and 0.050"

Let say the hydraulic compresses 0.00364" (0.006" @ valve) you can see the different in seat-to-seat duration. There will also be an increase in overlap.

Stan

VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00000____84.25_|_131.75_|_396.00_|__64. 52
_________0.00600____60.72_|__97.35_|_338.07_|__64. 46 << Seat duration Hydraulic lifter
_________0.01000____55.91_|__92.85_|_328.77_|__64. 42
_________0.02000____48.24_|__85.02_|_313.26_|__64. 29 << Seat duration Solid Lifter
_________0.04000____39.09_|__74.43_|_293.52_|__64. 00
_________0.05000____35.62_|__70.48_|_286.10_|__63. 81
_________0.10000____23.06_|__56.89_|_259.95_|__62. 80
_________0.15000____13.90_|__47.33_|_241.23_|__61. 49
_________0.20000_____6.12_|__39.33_|_225.45_|__60. 01
_________0.25000____-1.05_|__32.01_|_210.96_|__58.62
_________0.30000____-7.97_|__25.09_|_197.13_|__56.36
_________0.35000___-14.85_|__18.16_|_183.31_|__54.36
_________0.40000___-21.92_|__11.05_|_169.13_|__51.30
_________0.45000___-29.27_|___3.64_|_154.37_|__48.24
_________0.50000___-37.21_|__-4.30_|_138.48_|__44.38
_________0.55000___-46.08_|_-13.15_|_120.77_|__39.60
_________0.60000___-56.44_|_-23.48_|_100.09_|__33.78
_________0.65000___-69.51_|_-36.47_|__74.01_|__25.59
_________0.70000___-91.47_|_-57.99_|__30.54_|__11.31
CAM_______________________________________________ ______ICL
_________0.00600____56.01_|__92.95_|_328.96_|__39. 04_|_108.47
_________0.01000____50.50_|__87.43_|_317.93_|__39. 00_|_108.47
_________0.02000____41.86_|__77.65_|_299.51_|__38. 83_|_107.89
_________0.04000____30.98_|__65.35_|_276.33_|__38. 48_|_107.19
_________0.05000____26.89_|__60.95_|_267.84_|__38. 29_|_107.03
_________0.10000____11.47_|__44.82_|_236.29_|__37. 07_|_106.68
_________0.15000____-0.70_|__32.36_|_211.67_|__35.53_|_106.53
_________0.20000___-12.08_|__20.95_|_188.87_|__33.37_|_106.52
_________0.25000___-23.72_|___9.23_|_165.51_|__30.83_|_106.48
_________0.30000___-36.39_|__-3.48_|_140.13_|__27.21_|_106.45
_________0.35000___-51.53_|_-18.59_|_109.88_|__22.27_|_106.47
_________0.40000___-72.76_|_-39.65_|__67.59_|__14.31_|_106.55

[Steve C.]

I suspect the OPs UltraDyne solid roller cam consists of lobes R79 & R80 listed here: https://www.bulletcams.com/Masters/u...nemasters.html

276/284
243/251
162/170
.3883" lobe lift


If this is correct I used the same series of lobes 29 years ago in a 412CID combo.
Keeping in mind at that time they were 30+ year old lobe designs.
The cam card stated .026" lash (hot) based on a 1.5 rocker ratio for both intake & exhaust.



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[68WarDog]

[QUOTE=Steve C.;6495765]I suspect the OPs UltraDyne solid roller cam consists of lobes R79 & R80 listed here: https://www.bulletcams.com/Masters/u...nemasters.html

276/284
243/251
162/170
.3883" lobe lift


If this is correct I used the same series of lobes 29 years ago in a 412CID combo.
Keeping in mind at that time they were 30+ year old lobe designs.
The cam card stated .026" lash (hot) based on a 1.5 rocker ratio for both intake & exhaust.


That's correct Steve, and with the information guys have shared in this thread, I'll stick with the old reliable
UD/Crower hippo combination. However lash is .026 intake/ .022 ex. hot setting.

[Steve C.]

No argument here, only a FWIW observation. Years ago I ran the .3883, .4176 and .4267 series of UltraDyne solid roller lobes and all the cam cards specified .026" lash on both intake & exhaust.
That said Harold Brookshire has commented you can tighten them down.

Interesting comments by Harold Brookshire regarding lash in his post #6 here:

https://www.chevelles.com/threads/ud...ngevity.90773/


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