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Old 04-13-2021, 07:24 PM
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Default Hybrid Roller

With all these threads on failed hyd rollers, how do you know if a hyd roller cam can be used with solid roller lifters?

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Old 04-13-2021, 08:28 PM
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In theory you can run solid rollers on any HR camshaft. The cam lobe does NOT know what type of plunger the lifter is using inside of it. A solid lifter on a HR cam basically takes the hydraulic action of the lifter OUT of the equation, the roller and body still function in the same fashion.

I've seen some folks say it's not a good idea but I've never had a single issue with mine now and it's been in service since 2009.

I run the lash at .005" and it's whisper quiet compared to any other type of cam/lifter combo I've used in one of these engines. I'd also add that it is NOT RPM limited like I've observed with HR lifters in these engines. I've had a few on the dyno with HR's in them that "nose-dived" right around 5800rpm's. My engine will pull HARD right past 6000rpm's without the first hint of giving up anyplace.........Cliff

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Old 04-13-2021, 08:28 PM
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I would say "never". But then, I'm not that adventurous. Cliff has actually done it, I haven't.

"Hydraulic" cams don't have the longer clearance ramps ground into them that solid-lifter cams do. You'd be pounding the lifters with every valve opening, and slamming the valve shut with every closing. 'Course, this is mitigated somewhat by running tight lash.

Hydraulic lifters on a solid cam isn't as horrible. You'd have extended but un-needed clearance ramps making for smooth operation but relatively-speaking, a lot of time with the valve at very low lift.

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Old 04-13-2021, 08:37 PM
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ask the cam maker!Tom

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Old 04-13-2021, 09:07 PM
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Response from Mike Jones / cam designer.....

A few years ago I e-mailed him and asked if 150 lbs seat pressure might be ok with using solid roller lifters with the Comp Magnum High Lift hydraulic roller lobes number 3122 & 3120 used for the Old Faithful cam. His response:

"I don't know enough about the ramps used on those Comp lobes to be able to tell you what seat pressure you need. If they're gentle, 150# might be fine, if they're aggressive, it could take 180# on the seat. Some hydraulic roller cams have an opening ramp that's too aggressive to run with a solid roller lifter. You'll need to check with Comp, so you don't run into any issues."



.

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Old 04-13-2021, 09:13 PM
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Quote:
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ask the cam maker!Tom
Exactly.
Steve's post is dead on as well.

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Old 04-14-2021, 12:15 AM
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If I recall correct, Cliff is running a comp XR XFI profile, if that profile is quiet with Aluminum heads, I am going to say there are not many HR cams more aggressive off the seat than those profiles. It is one of the more more difficult hybrids to set the lash with solids. Cliffs results speak for themselves, if he can make that profile work quietly with aluminum heads, then the list of cams that won’t work on a hybrid Pontiac is going to be pretty short.

The Hybrids are basically very tight lash solid rollers with constant velocity (CV) lash ramps. For it to work correctly the lash needs to be set so that the lash is removed by the end of the CV ramp. If the cam designer is no help, the easiest way to find the end of the CV ramp is to use a degree wheel and measure where the velocity changes on the opening side of the profile. On a HR it seems to be right before the cam has .001” of lifter rise per degree at the crank. Then multiply that tappet lift by the rocker ratio and and you will have a target for the max (hot) lash. Most of the HR profiles Brookshire designed hit that around .004” tappet. Some of the lazier HR’s like the CV is closer to .006” tappet, and can run .010”-.012” lash.

A proper designed ultra tight lash sold roller has a gentler lash ramp on the exhaust to allow for the expansion so they still operate quietly.

More problems occur with the hybrid when the expansion rates are higher. A example would be if you were running a Aluminum block, Al heads, and either a small 6 mm valve stem or a really long valve stem like a KRE high port. Even with zero lash, once hot they expand enough that the lifter is opening the valve well after the end of the CV ramp. In those cases your much better off with a solid roller design so the lifters stays on the CV ramp and not up into the profile. IRC, Bigger rocker ratios help with the expansion with aluminum components, not an issue on a cast iron stock valve Pontiac.

You can usually gauges the CV ramp on a HR cam by looking at the intensity from .050” to .006”. 54* or greater are usually better candidates for hybrids. But even most the 50* intensities seem to work ok, they are just more trouble some to set the lash on.


Last edited by Jay S; 04-14-2021 at 12:16 AM. Reason: Edit
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Old 04-14-2021, 07:33 AM
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Keep in mind here that a hydraulic lifter is basically a solid on the up stroke since oil is not compressible. There is a very slight "cushion" based on the bleed down rate of the lifter vs the number of cycles it's making per second. So if your lifters have a 120 second bleed down rate, for example, it's pretty much a solid lifter at any RPM and not allowing much downward movement of the plunger as the lobe comes off the base circle. A "fast bleed" lifter would provide more cushion, especially at lower RPM's.

I've never seen why we couldn't run tight lash solid rollers on any cam profile without issues. I've done it successfully here on several engines and all of them have been in service well over 10 years at this point. They are also very quiet and no indications of RPM limitations either.

Your cam manufacturer woln't really be able to tell you if it will work or not. To date I have not once read anyplace where going this direction has failed miserably. It's just one of those things you'll have to jump in and get dirty with. When I went that direction I experimented with lash, starting out at .010/.012" intake/exhaust. Once fully warmed up they would "grow" about .002-.003" or so. So I started lashing them tighter and ended up settling on .005" as a good place to be, super quiet even fully warmed up. I also could tell this was more effective as it reduced engine vacuum some, so also utilizing more of the lobe profile......

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Old 04-14-2021, 09:06 AM
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Unless changed Cliff, like so many, is using the Comp Magnum High Lift hydraulic roller lobes. As Tom S used with solid roller lifters.


.

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Old 04-14-2021, 09:26 AM
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If it's failure you're concerned with, using the solid rollers doesn't get you out of the woods. They can fail just as easily as the hydraulics. Link bars can break, wheels can break off, and on top of that, if you run enough spring pressure with some of these solid roller profiles, you then have to worry about needle bearing longevity, something that hasn't been an issue with hydraulics.

The whole reason that this hybrid deal got started in the first place was because of inconsistency with the internal bleed down rates of the hydraulic rollers causing noise that people just didn't want to deal with, it wasn't because of failures.

Quite honestly, the breakage is so few and far between when you consider the grand scheme of things, that I just don't concern myself with it. You either roll the dice, build yourself a roller engine, or put a flat tappet in it.

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Old 04-14-2021, 09:38 AM
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My hybrid has been humming happily along for eight years and 1000's of miles. IIRC mine are set at .005.

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Old 04-14-2021, 04:31 PM
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Quote:
Originally Posted by Steve C. View Post
Unless changed Cliff, like so many, is using the Comp Magnum High Lift hydraulic roller lobes. As Tom S used with solid roller lifters.


.
I was mistaken then. Must have been Cliff’s earlier engine that used the XFI lobes then with regular comp HR lifters and the current one is a magnum profiles with the Crower lifters as a hybrid. Maybe Cliff can correct that for sure, I thought he told me he was using XFI’s.

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Old 04-14-2021, 05:37 PM
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Quote:
Originally Posted by Jay S View Post
I was mistaken then. Must have been Cliff’s earlier engine that used the XFI lobes then with regular comp HR lifters and the current one is a magnum profiles with the Crower lifters as a hybrid. Maybe Cliff can correct that for sure, I thought he told me he was using XFI’s.
Thanks Steve. Went back and looked and I forgot Cliff is running a earlier Old Faithful cam with magnum lobes. Makes sense, XFI as a hybrid with solids would be noisy at .005” lash cold running aluminum heads once warm.


Last edited by Jay S; 04-14-2021 at 05:41 PM. Reason: Add
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Old 04-14-2021, 05:44 PM
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I ran a custom ground Comp cam with XFI lobes in my last 455. It was topped with HR lifters but it's been so long ago I don't remember who supplied them. Most likely they were Morel. I had to run the plungers DEEP in the lifter bodies to keep them quiet but they worked OK otherwise, unless you tried to go past 5800rpms. That was never an issue because the cam was done at 5400rpm's and I typically short shift when racing anyhow down around 5000rpm's.

The new 455 uses Dave's Old Faithful cam, the early version with the Magnum lobes. It's fine with Crower HIPPO lifters lashed at .005". It's by far and above the quietest engine I've had in the car as far as valve train noise is concerned, and it has no RPM limitations. I've spun it to and past 6500rpms a few times and it doesn't even think about quitting.....FWIW......

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Old 04-14-2021, 10:41 PM
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I also run a hybrid setup........ no issues so far and I hope to have long term success that others have had.

That being said, it is not for everyone. Like Cliff mentions, if you want to run a hybrid you pretty much need to dive in and get dirty. Very few are going to recommend or support you in the end.

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Old 04-15-2021, 07:29 AM
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+2

That's for sure Mike, at some point with ALL of these things you've got to just get out from behind the get off Google, get out from behind the keyboard and dive in. I've seen all sorts of folks bash the "hybrid" set-up but not in one single instance have I read anyplace that someone tried it and it failed miserably. It may be as I mentioned earlier in this thread that the lobe just doesn't know what type of plunger is inside the lifter. With a tight lash solid lifter set-up you are basically using a true anti pump-up lifter and nothing changes internally with it over the entire RPM range.

I've even pondered running the lifters at zero lash instead of .005" as they grow a few thou in use. That would sure be easier as far as adjustments are concerned as working with a .005" feeler gauge laying over the fenders, especially on the two rear cylinders is no fun at all!.........

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Old 04-15-2021, 09:58 AM
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As long as the valve terrain is opening on the constant velocity of the lash ramp, there should be no disadvantage to changing the lash narrower or wider on a hybrid.

I know plenty of people think they are great, but on the street I am not a fan of the cams like comps extreme energy XR or the XFI with shorter seat timings, and shorter CV ramps to match the profile. When the bleed rates of the lifters is enough that the valve is opening after the CV ramp, it is comparible to running a hybrid lashed beyond the CV ramp, only now it has a lighter duty lifter trying to control the hammering. Going that direction with fast ramps better step up and get a better quality lifter, or go the hybrid route and zero lash it cold. Some of the lifter problems are poor craftsmanship, but plenty of problems are also a miss match of components like the wrong HR lifters for for a profile. At least with the hybrid the SR lifter is rated for 700 or more lbs with a .75” roller versus the HR lifter rated for much less pressure a a smaller .70” roller. Plus your eliminating the random bleed rate. Pretty much all those aggressive HR hybrid guys end up going the zero lash cold.


Last edited by Jay S; 04-15-2021 at 10:11 AM. Reason: Typo
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