The Stovebolt Site Forums The Shop Area Engine Shop Hydraulic vs. Solid camshaft?

I'm sure this has been talked about before, but how do you determine a solid cam from hydraulic without some paper work or looking at the lifters or some i.d. numbers. Is there a way buy looking at the lifter bodies? I should know this, maybe a picture or too, thanks there Bolters.......

A solid lifter has no moving parts...

Stock hydraulic cams have equal lift on all lobes.

That's interesting Dave. Can you expand on that and explain why the intake and
exhaust valve lobe lift on a hydraulic cam would be any different than it is on a solid lift
cam?
I would have thought that the lobe lift would be the same in both engines and only the
cam profile different as a method of coping with thermal expansion and acceleration of
the hydraulic vs the solid lifter. I can understand there being differences in the ramps,
flank and nose of the cam to compensate for valve lash in a solid lifter engine and slight
differences in the duration.
Because the Chevy six head design is not the most efficient, I would have thought that
both hydraulic and solid cams for a Stovebolt would be dual-pattern designs.
Thanks
Denny Graham
Sandwich, IL

The exhaust lobe is taller on a solid cam to compensate for the wider lash setting(I believe).

Dave, that's a good guess- - - - -wrong, but good. It will work as an explanation for the low-information crowd.
Jerry

Don't keep us guessing Jerry, why is the exhaust lobe taller on a 216/235 solid cam?

Like I've always said that there Dude in Dellrose Tn. registered in Feb. of 2004 wrote the book on these here Stovebolters? Hey when Hotrod Lincoln talks everybody listens.

Since I'm just filled with low-information I guess that makes me
part of the low-information crow, so I'm all ears HRL, that's
why I axed.
Man, you must have been one tough teacher for sure.

dg

The clearance ramp on a mechanical lifter lobe has no effect at all on total lift, which is a function of the diameter of the base circle compared to the height of the lobe. Exhaust lobes have a wider clearance built in to accommodate the fact that exhaust valves run hotter than intakes, and the stems grow more at normal running temperatures. A "clearance ramp" is an area of slow, gradual lift just off the base circle designed to stack all the valvetrain parts together slowly before the lobe slaps the valve open pretty vigorously. Hydraulic cams also have acceleration ramps, but they're very short and they only lift 2 or 3 thousandths before the rapid lift begins. There's a corresponding slowdown area at valve closing to keep from battering the valve seat as the valve approaches, and then the clearance goes back in on the solid lifter shaft to reestablish the clearance. Different cam grinds have different amounts of clearance built in, so always use the manufacturer's lash specifications on a non-stock cam.

Higher lift on an exhaust valve usually develops more low-end torque, so solid lifter cams designed for use with standard-transmission applications probably used more exhaust lift to help with acceleration away from a stop. The hydraulic-lifter engines were originally used with torque converters and automatic transmissions, so the issue of breakaway torque was probably less critical since the torque converter essentially doubled engine torque when pulling away from a stop.
Jerry

...and when a frog jumps, he bumps his butt, unless, of course he were to have wings.
My point is, the question was about lobe lift on hydraulic vs. solid lifter engines.
How does a badly shrouded exhaust valve have anything to do with the OP's topic?
Thank you for sharing, but am I missing something?
Carl

You're just too clever for me.

I believe what Panic was stating,is the fact that the stovebolt combustion chamber has the exhaust valve up inside a big cavity, while the intake valve is flush with the deck of the head. This causes the exhaust valve to be more "shrouded" than the intake valve.

So, the way I am reading HRL's post, HE DOESN'T KNOW! If he does know, we are just too big of PEONS to grace us with his sort of sketchy knowledge. Anyone can look up the highly educated knowledgeable cam engineers answer. What we need is the SENIOR in high schools answer. But I guess he doesn't know that. I feel so sorry for his students. But then, my high school auto mechanics teacher was the coach too!

You know, this is a normal occurrence here. We are all stupid, and he is all smart. Have any of you noticed how you NEVER see pictures or links from this guy? He could be a 40 year old living in his moms basement who gets of all sorts of internet sites and just makes himself a nuisance. Who really knows?

Pre68Dave does not make guesses. He has what you call REAL experience with the very vehicles we talk about here. If I need to know ANYthing about engines, I have his phone number and I call. What we were hoping for, was teacher to student information, you know.. the information that leads us to understand the issue at hand.

Any of you lambasting me for saying this, please THINK about it first.. He has nothing good to say about anyone, yet wants to lead us all on and NEVER give direct answers. Its getting so tiring, I just HAD to say something. Plan on MUCH MUCH more!

Sometimes one must first shut the mouth and pay attention. Then ask questions.

Or, Mr Post Count, maybe we could get the OP a real answer. One that many of us are interested in. Shut mouth until you KNOW the answer! Any of these posts, that are not directly related TO THE ANSWER should be deleted by the moderator. Mine included. Amazing how the guys you THINK know, don't know, but like to snipe at people instead. How does this serve the Original Poster and those who really want to know? Whoosh! Right over my head here!! Am I alone?

Off your meds again, Deve?

Jerry

No, quite coherent these days. In case you haven't figured it out, this is not the HRL 'belittle the other guy' show. Here, at least the way I understand it, we don't use ignorance to get our point across, we are NICE to everyone, and we give our information out freely FOR THE PURPOSE OF HELPING OTHERS!!!

Saying stupid stuff to other professionals like Pre68Dave like "good guess.. wrong, but good" doesn't make anyone feel like YOU are one of those willing to help. You do this all the time. How about we do some introspective analysis and just be the teacher?

We all want to know the questions we ask. Nobody here EVER that I know of asks a question just to annoy. There is a good reason for the question. This is the way we all should treat a persons question. Meds my arse! How about if you don't know, you don't lambast those who might? We all see this all the time. Its old now.

For what its worth, before this thread gets locked down.
I read it all, and use what I can sort out for my own use.
However, I've met, and chatted with HRL a few times and I'll bet he don't go into much more detail because his answers will be far far about our understanding....although I like to read it.

I'd suggest this may be a time for one on one PM's and then perhaps, in the end, it all gets posted in plain English?
Does anyone understand what I'M trying to say?? Probably not.

Thats the problem for me. Call me stupid, but I just dont know the difference between a solid cam and a hydraulic cam and why. Did I miss something? No, I didnt. This is normal operation for some folks. Dont profess to have EVER taught a group of high school students and then not be able to get that big brain to translate into student mode. Makes you look like you just like to take advantage of people's good nature. I am here for you people! Its no longer funny.

A normal person understands perfectly what you are trying to say. But in this case, we have people who think they are above everyone else and cant be bothered with us peons. YET THEY POST THEIR TRIPE ANYWAY!

I think the OP was wondering how you would tell a hydraulic cam from a solid cam if all you have is a cam sitting in front of you. (at least that sounds like what he is asking to me)

A very good question. My interest is genuine especially now. My machine shop ordered the cam and I would love to be able to tell if its the right one. Then, after that question is answered, I would like to know if the machine shop sent it off to the cam grinder to give me 'performance characteristics', and its hydraulic, what do they do to make it better? I have always been told that if you want performance, go with solid lifter cams. Its a worthwhile conversation to have.

I agree with you on that, and what Panic stated for that matter. But it would seem to me that a shrouded exhaust valve will still be shrouded regardless of whether you had a hydraulic lifter cam or a solid lifter cam. That is why I asked panic if I was missing something.
Carl

When I was in high school several of my friends were Olds freaks. I liked them so well that I bought a GMC 550 that was born with an Olds 371. It was common to put in solid lifters in those days simply because the radical cams were designed for solid lifters. These were usually high lift cams with a lot more duration than stock. I have been told that a cam for hydraulic lifters started lifting more abruptly than a solid lifter cam, but I never tried measuring the difference. I think this is the "clearance ramp" that Jerry is talking about. We had the idea that solid lifters were better at high RPMs, but again the really radical cams were solid lifter cams. I also played with GMC and Ford Y-Blocks which were born with solid lifters. Back in the 50's, a Y-block would wind up a lot higher than GM V8s that were born with hydraulic lifters. But there were other factors that we didn't consider.

I don't know much about cams past the Olds Rocket years, but I don't think anyone could tell the difference by looking at a cam for mild street hydraulic or a cam for mild street solids. I think a lot of engines were retrofitted with solids back in my day just for bragging rights. However, there were guys that went to the old Double Eagle strip in San Antonio and the serious competitors had solid lifters. I was down there with Y-Blocks that were born with solids. There is still a group of serious Y-Block guys. They are very serious about the sport and they now run roller cams. I'm not a participant, but I enjoy reading their literature.

The Engine Pro MC323 Cam I started with (Hydraulic) got a 268 grind. Machine Shop has it listed as a "Torquer" grind. Apparently they take a precision amount of meat off the bottom of the lobes to increase height(?). Problem is, I can't find any information online about this cam so I can compare it spec wise to a solid lifter cam. Their web site has forgotten about us!

235 268H Cam is a 268 duration cam with a .525" lift. I just wish I had a solid lifter cam laying around.

A torquer grind is probably what later Oldsmobile people called an RV grind. An RV grind was used when Olds engines were installed in RVs and it provides more low end torque. What are you expecting to get out of your 235. There is really nothing wrong with hydraulic lifters. GM started using them in the early 50's and with a good detergent oil, they had no problems.

I am pretty realistic about these vintage engines. I do not want to RUN someone on the street, just have a clean, peppy engine that gets me from A to B. I know there is very little horsepower and reliability is the most important, yet I want the cleanest, best running build I can get. Yet QUIET is important to me. Clacking top ends are annoying. And then there is the level of experience. Its so much easier for me to just crank the rocker down plus 1/2 turn and it just works. Quietly, smoothly, yet produces the horsepower to make it a viable daily driver today.

Problem is, I don't know what I want really. So I tell the machine shop I want a little better performance on this engine, yet I do NOT want a RUMPY idle. He says, I know exactly what you want.. and HERE WE ARE! :)\

My next article will be on solid lifters. When I get there, I will be asking more questions and learning so much more. Can't wait!

Start learning more than just lift and duration. Lobe center, cam timing, effective compression ratios.
Not trying to be a smart [censored] but some stuff is mathematics and does require the aptitude to understand it and effectively apply it.
That's why sometimes the experts are needed even if one can't speak their language.

so now I am really confused the OP was ol'55, but somehow now Deve has assumed the role of OP, and I still haven't seen anything from ol'55 clarifying his statement(s) I don't know if he has a cam AND lifters in an engine, on the bench, in a box. Or if he just has a cam and is wondering which lifters to buy. Or is just curious. I do so wish ol'55 would reply. Whatever the case Deve, there is a pile of information on this subject online. and as Don said, just keep studying up, it is actually pretty interesting.

I am just providing the information on the hydraulic one, hoping someone else will chime in on the solid one. Is there no way to take a calipers and determine the differences that would only be apparent between intake and exhaust, or between solid and hydraulic?

A guy puts a solid lifter cam on the workbench alongside a hydraulic one. He comes in the next day and forgot which one was which. How does he tell?

I always put cams in V Blocks and turn them before I install them because no matter what some people say, I have seen old cams get bowed from long storage laying flat. I think this same setup could be used to compare 2 cams. Everyone I have known in days past seemed to agree that hydraulic cams lift more abruptly. I would think that mounting a cam on V Blocks, rotating it with a dial indicator on a lobe would tell the story. I would probably mount driven gear on the cam and use the teeth for reference points. I think you would find a hydraulic cam to move the dial indicator much quicker than the solid lifter cam. Total lift can be calculated by multiplying by your rocker ratio. I still think the abruptness of the lift is what Jerry calls "clearance ramp". I don't know technical words because my formal education was in accounting and pre-law. But I did build some pretty quick engines 50 years ago which disgusted my parents. My mother would have rather raised a lawyer like her family had been since the 1700's and my father would have rather seen me in a white shirt hiring maintenance done like he did. But I was happy with being called a hoodlum back then. I think now they call them motor heads. I overhauled my first Cummins Diesel over 45 years ago, and I still run all Cummins and supervise maintenance and do a lot of trouble shooting.

A "clearance ramp" is an area of SLOOOOOW lift where the base circle transitions into the lifting portion of the lobe. For instance, if a cam has a .006" intake clearance specification, that amount of lift (times the rocker arm ratio) is ground into the lobe to allow all the parts of the valve train to get into solid contact with each other before the faster lift associated with actually opening the valve gets under way. It's easy to see if a degree wheel is mounted on the crankshaft and a dial indicator is positioned to monitor cam lobe or valve motion. The dial indicator will show a slow lift until the clearance is taken up, then the rate of lift will increase quickly as the valve is forced open. On the closing side of the lobe, the rate of closure will be very rapid until the valve ALMOST touches the seat, then it will slow down and drop it onto the seat gently- - - -then the clearance gets re-established.

Adjusting to the wrong clearance will result in battered valve seats, and/or incorrect timing of the opening/closing event of the valve. Since hydraulic lifters never actually have any clearance, the slow beginning and ending portions of the lobe are much shorter duration and of less "lift" than with a solid lifter cam. It's possible to run solid lifters on a hydraulic cam, but the clearance MUST be adjusted to approximately .003"-.004", and the valve action might be noisy unless the clearance is monitored and corrected very frequently.
Jerry

Re: "235 268H Cam is a 268 duration cam with a .525" lift"

Did you actually measure the valve lift, or the lobe height (the bump's height above the base circle)?
From that lift figure, I suspect that the spec he gave you was for that grind installed in the 250/292 Gen-3 engine with its higher rocker ratio.
To get .525" lift in a 235, the lobe would have to be .355" tall which I suspect is beyond the safe limit for a 235 cam (which has an original lobe height of about .210"). There's just not enough material to do this.

That was the machine shops numbers. I really don't know for sure how its measured. Fascinating conversation for sure. Jim, the machine shop owner is very very busy, so I dont like to pester him with more information unless its really important. He is second generation and has racing roots and connections, so I am sure he knows what he is doing. Wish I knew half.

You should get the real numbers before you assemble the head, because that lift will be really tight for coil bind, and also puts the intake valve very close to the piston dome @ TDC.
To get the approximate lobe height:
You need the camshaft, and a caliper.
Usually the critical lobe is the intake, remember that they are positioned on the stick in the order that the valves sit in the head: Ex In In Ex Ex In In Ex Ex In In Ex.
Place the cam on a flat surface with the subject lobe pointing directly up. Now measure the width across the lobe - this will be the base circle diameter (but only because this is a mild cam).
Now rotate the cam 90° in either direction and measure across from the lobe to the opposite side. Subtract the base circle (above) from this - it's the lobe height. Multiply by 1.477 (the stovebolt Gen-2 rocker arm ratio) to get your gross lift at the valve.

268H is a Comp Cams number- - - -Engine Pro cams all have 4-digit numbers and they don't make cams for Chevy inline sixes.
Jerry

That makes sense. Even though the color sticker says Engine Pro with the number MC323 is on the box, but then he shipped it off for the performance grind. Now I can go to the Comp Cams site to learn more! Thanks!

I never really thought much about the cam other than it needs to be hydraulic for hyd lifters and solid for solid. I should have it running here in a few weeks. Cant wait. Great information Panic. Thanks! Anytime I can pick up deeper information, I appreciate it very much. I just hope the OP got his question answered. Best way to tell the diff between the two at a glance.

Well I'm back here to check out my original post here on the subject of the difference between the two camshafts. I was quite surprised to see how many Bolters submitted there replys, most time I submit a question I'm lucky to get abot 2 or 3 replys, so looks to me you Bolters pretty much summed her up, or should I especially credit Hotrod Lincoln. I believe Jerry even had something to do with a frozen whale going up over the Fwy. 5 Grapevine in a Diesel at over 100 mph? THATS A WILD MAN THERE.

LOL! Forgot about that post! I never had the opportunity to meet Tyrone Malone, but we were both in central California about the same time in the mid-1970's. He had an Allison V-12 gasoline engine out of a P-40 fighter plane in the rig that topped the Grapevine at 120 MPH (loaded) and got that famous speeding ticket. It ran 115 octane aviation gasoline at the rate of 7 gallons per minute at full throttle. He built some killer Diesel trucks a little later. Quite a guy!



Jerry