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BBC solid roller vs hydraulic roller.

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#22 ·
JIM said:
I’m in the middle of a freshen up of my engine in the Chevelle. I’ve been running the Comp XR286R solid roller for a long time. I see guys on here running fast ETs and making a lot more power than I am while using hydraulic roller cams. I can get a HR cam with similar duration numbers as my current solid but I realize there is much more to that. Like the ramp rates and area under the curve.
Keeping my compression the same while improving my heads slightly (new 11/32” valves vs the original 3/8” valves and a complete valve job) could I make the same or more power with a hydraulic roller while having a bit more reliability and no lash concerns?
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if you’re looking to switch from a solid roller to a hydraulic roller cam, it’s definitely possible to make good power while upping your reliability.

The key’s in those ramp rates and how they play out over the curve. With the head improvements you’re talking about, you should see gains.

Plus, less time dealing with lash adjustments is a win.

Just make sure the rest of your setup can handle the change.
 
#25 ·
mrpaticular said:
Even if the profiles are similar the hydraulic will fall off at a certain rpm where a solid will reach that same rpm and has the ability to carry the rpm out further.
That can give you more flexibility on shift rpm.
Rick
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As far as similar in cam specs they won't be. The solid roller will need to be larger to make up for mechanical lash. I've got hyd roller stuff stable to mid 7000 rpm range.
 
Discussion starter · #26 ·
cstraub said:
As far as similar in cam specs they won't be. The solid roller will need to be larger to make up for mechanical lash. I've got hyd roller stuff stable to mid 7000 rpm range.
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That part I don’t understand. Don’t the HR cams run a much lighter valve spring?
I believe you, but how do you not get valve float at 7500 rpm with without the big spring pressure that a SR runs?
 
#27 ·
JIM said:
That part I don’t understand. Don’t the HR cams run a much lighter valve spring?
I believe you, but how do you not get valve float at 7500 rpm with without the big spring pressure that a SR runs?
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I have access to the software that the OEM's use for simulated valve train testing by computer. We input all the weights of the components to be used and then design a profile that to make power in the given rpm range that is needed without valve float. With the the state of flat tappet cores we took the valvetrain limits of a class that has to use an 1.260 spring and designed a solid roller to run up to 7800 rpm with that valve spring on "computer". On the dyno it ran to 7800 and was stable.
 
#29 ·
Morel 7790 limited travel hyd roller lifter in a drag and drive. Just put 1100 miles on car and won his class out at the event just held out west.....
Image
 
#30 ·
So that's basically a solid lifter cam that they can call hydraulic. Limited travel lifters are more of a "grey area" to get around class rules where they require a "hydraulic" lifter. We used them in stock car engines that couldn't have a solid lifter.
 
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#31 ·
bracketchev1221 said:
So that's basically a solid lifter cam that they can call hydraulic. Limited travel lifters are more of a "grey area" to get around class rules where they require a "hydraulic" lifter. We used them in stock car engines that couldn't have a solid lifter.
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All correct, a lifter that functions like a hydraulic but you can put spring pressure to it like a solid. They are noisy but as you can see will take rpm. Available in BBC.
 
#33 ·
7000 rpm and under go hydraulic for street cat BBC 2.300 steel valve PSI max life valve springs good lifters Jonhson / Morel
 
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#34 ·
I think intended use of the car along with maintenance come into play. If you are not looking for that last hp and keep the rpms down (though they have gotten pretty good with hydraulic roller these days - short travel lifters, light weight valve train, good springs, etc). For a street car and not have to worry about valve lash the hydraulic roller is the answer. My LS motor goes to 7,000 rpm very easy but the titanium valve weighing only 75 grams along with the smaller 1.30 spring and a light weight rocker all helps. My BBC revs pretty good also a hydraulic roller but the valve is like 140 grams and needs more spring - I use the medium travel lifter in both engines (oil column is .093 tall versus .058 for short or .200 for OEM). The medium travel has a lot of the advantages of the short but not the exactness required for the preload and has a .025 to .045 preload window. This was more important on my LS motor as I do not run adjustable rocker arms.
 
#36 ·
Jim, as infrequently as you use the car why not keep that proven cam you already have?

Admittedly though, I had that exact cam in my 502 and did run the fastest mph the car ever did, but didn't lose a whole lot going down to a 224/228 HR cam. My OCD would not allow me to run a SR cam anymore.
 
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Discussion starter · #37 ·
Vince, I’m just not sure that cam is best suited for this combo. I’d like it a little smoother of an idle and a tad more tame. I’m leaning towards HR
 
#38 ·
Jim, contact Chris Straub and let him grind the cam suited for your combo and your needs/wants. Solid or hydraulic.
He spec'ed a solid roller for me that was exactly what I needed/wanted. 253°/268°, .654/.638, 108lsa. Drives around well at low rpms, (cleans up by 1700-1800rpm) and pulls hard past 7k. If you use good components with a solid roller setup, you won't have any issues and lash doesn't change. My Isky bushed lifters had 20k miles on them when I sent them back for a rebuild and after inspection Isky said they were good and didn't need rebuilt. Had them rebuilt anyway because I was switching to Chris's cam and wanted fresh lifters and springs.
 
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