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Old 02-02-2005, 03:13 PM
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Solid cams vs Hydraulic cams, preference or power?

So I've been thinking lately about my next upgrades for my motor. One thing I have noticed about the motor is that it swallowed a lot more cam than I thought it would. The 280 comps magnum flat tappet grind is nice, but it really doesn't cam all that much, and I think my motor could use a bit more cam on the top end. This is not to say it doesn't set you back in your seat...

That aside, I'll surely go roller on my next cam. But this really begs the question: hydraulic or solid? I've read quite a lot of threads on the database just to see what the classic arguments for each are. It seems most people don't recommend solids for the street, or anything that doesn't see the north side of 6000 RPM very regularly. However, companies like comps make solid and solid roller cams at durations as low as in the advertised 260 range. These cams have powerbands that top out around 6000 RPM or lower, which sort-of defeats the above logic by showing that a large company makes and sells cams, and people are using cams that are solid for low to mid RPM applications.

Another argument against the use of solid cams is that they require maintenance and are therefore street-unfriendly. I would suppose, like anything else in hotrodding, this is also a partial truth. I.e. if you have some nice rockers like the harland sharp units I've invested in, this is probably not as much of a problem. I would also argue that this is not really a daily driver car (although in a pinch it could be). Its got lots of compression and runs a stall, and is getting some pretty nasty gears; it was never meant to be too awfully friendly in the first place.

Lastly, some argue that given that the technology of hydraulic cams has advanced so much in the last 20 years, solid units are really obsolete for anything but the most hardcore racing applications. Surely technology has advanced, but probably on both ends of the fence. I suppose what would be a great test of this theory is to take a similar grind cam and run them on the dyno, do a 1/4 mile pass and see what the differences are.

If you have a hot motor, why not run a solid? Is there really anything other than the half-myth about constant adjustment to deter one from using it in a weekend car?

Obviously I'm looking for an excuse to buy one. What do you guys think?

K
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Old 02-02-2005, 03:19 PM
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Do it. You'll get more area under the curve by means of faster ramps. Something hydro's can't do. Lash adjustment's are periodical. I check the lash on our open engines every race. Not to readjust but to look for signs of failure.
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Old 02-02-2005, 03:24 PM
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When the hot rod world for factory cars exploded, just about all you could get was a solid cam as the factory guys knew this was the way to go. there`s more you can do with a solid than a hydraulic performance wise, but the added hassle of having to adjust the valves can get old fast. Some say they`ve never had to readjust the valves, I`ve never worked on one where they didn`t need readjusted. Others don`t like the nice little "tick" they give off and would rather not hear it.
However, Roller cams leave both in the dust as far as technology goes, so if you`re gonna go roller and don`t mind the added work, go with a solid. It`s said valve train parts can and will wear out sooner, as the solids aren`t as easy going and "soft" as the hydraulic. the engine I`m putting together now will have a hydraulic roller, why hydraulic? since it`s my daily driver and I`d rather not hear them tick, and I don`t want to have to readjust the valves anytime soon. The hydraulic is the lazy man`s cam, not to say I`m lazy or anyone else is that runs one, but to adjust them and not have to worry with them or hear any ticks is rather nice.
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Old 02-02-2005, 03:41 PM
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One advantage of a solid is that you can set them and know each rocker is spot on. no guessing if you need a 1/4 turn of a full turn of preload.
I prefer a solid and would have gone with a solid roller if the budget allowed, but as it didn't and i already had hyd roller lifters...
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Old 02-02-2005, 03:42 PM
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Only one choice

Hey,
If you are going to go solid, why not go solid roller?

Solid roller cams do make alot more power for a given level of streetability. That is a fact. You can get faster ramp rates and more lift for a given duration. No flat-tappet can match a roller cam unless you are running a chrysler engine w/solids where tappet velocity can be higher due to larger lifter diameter.

If I had an adjustable valvetrain setup on my engine, I wouldn't hesitate to run solids. I think they are a very good bang for the buck. I have also heard that materials and metallurgy are alot better nowadays and they don't need as frequent adjustment (used to be every 750-1000 miles?).

If you are lazy but still want a roller cam, run a hydraulic roller. The only issue is you are limited to around 6000-6200 rpm MAX because of spring force limitations and heavy lifters.

The real issue about roller stuff is cost, as well as some of the solid roller lobe profiles being really hard on valvetrain parts (drag profiles).

I have heard you can gain up to 40 hp by switching from a hydro cam to a solid roller with similar duration specs. Have not personally tried a back to back comparison, though.

If it was me and I had the funds, I would stick a nasty solid roller in there with +.650 lift and hold on to my britches.

Good Luck
Andy

PS Don't assume a "stall" will be sufficient for your cam. It is good to know the actual stall speed, otherwise you are not applying your engine's power efficiently. The rear gears are a great idea, though. No need to have 4.56 gears with a 220@.050 cam, make sure to match.

Last edited by fearsomefairmont; 02-02-2005 at 03:47 PM.
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Old 02-02-2005, 05:18 PM
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If I ran a solid I wouldn't bother with a flat profile.

.650 lift would be a little too radical for the heads I have, plus I don't have a rotating assembly that's going to handle the RPM's that that profile of a came is going to deal in.

I have run rollers before, just not a solid. I'm interested in a racey ride.

Part of my question is when you take away the high R factor for needing a solid roller (which I won't be spinning) how much more are you getting by going solid than hydraulic when you go roller? The way a cam is going to make more power is area under the lobe, and given that roller cams have very few limitations on angle of attack on the lobe ramp, how much difference is there?

K
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Old 02-02-2005, 06:02 PM
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Well I see a lot of people saying "just go solid roller" I would be willing to bet most if not all of them have never run a solid roller cam on a real street car. They have come a long ways but they are still not street worthy (IMO). I did run one on the street and it was a disaster. Now before someone says, it was a fluke or I did something wrong. That is not the case. When I bought my "street" roller, I was told it "should live about 25K miles on the street. It didn't make 2500 miles before the roller lifters started breaking. You haven't seen damage until you see what a bunch of little roller bearings running free do to an engine. I used all name brand stuff (I will not mention the company) I bought every recommended part as a kit (cam, lifters, valve springs, rev kit, button, stud girdle).

Solid rollers are very rough on valve springs and you MUST keep a close eye on your spring pressures and lash. Idling is also rough on them.

You will hear people swear up and down they know someone that runs a solid roller and never had a problem with 50K street miles. I highly doubt it. If you don;t keep an eye on your spring pressures and they get weak, the lifter will bounce on the cam and the little rollers will get flat spots on them shortly after that they fail. For every success story I bet there are two disaster stories from running a solid roller on the street.

The only real reason to run a solid roller is if you need a cam so radical (to match the rest of your combo) that you can't get there with a flat tappet solid cam (IMO). While it is true you can get more lift with less duration with a solid roller and higher lift rates, unless you are on the ragged edge (which most pump gas cars aren't) then there just isn't "much" benefit in it.

Now remember I am talking TRUE street cars (meaning get driven often on the street/highway and run on pump gas). A engine has to be built different when you are talking in terms of miles versus 1/4 miles. A street car goes thousands of mile between any maintenance, a race car only has to make it a fraction of a mile before things are checked tuned, etc... If you don;t plan to do that with your street car a solid roller is not the best choice. If a roller starts going bad in a race car it is found within 1 mile even in the worse maintained cars, in a street car if it starts going bad it may go un-detected for thousands of miles (by then it's too late). You won't even notice the decline in performance because you will not be driving around on the street at full throttle so you won't see the performance fall of or valve float (which is an early sign the springs are going away).

If you are talking a race car then a solid roller is a great choice.

There are only two good lifters that have a chance to live on the street, they have direct oiling to the lifter bearings. Look into the price of those. You will be about $650-750 lighter in the pocket when the roller is set up (correctly). You can't tell me for that kind of money you couldn't gain the same amount or more performance in a street car by doing something different.

I spent a lot of time and money on my blown engine, I could have put any cam in there I wanted to, I chose to go with a solid flat tappet cam. I check the lash when I do oil changes and I have yet to see it need adjustment.

That's my $.50 worth

Royce
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Old 02-02-2005, 08:24 PM
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solid vs hydraulic

As was mentioned earlier, you will have a lot more area under the curve with a solid lifter vs hydraulic. That being the case, solids generally have a higher lift per duration than do hydraulics.
One thing to consider when looking at durations.
As a general rule, given a solid lifter and a hydraulic lifter cam, with the same duration, the hydraulics operating range will be roughly 500 rpm higher than the solid; IE: a 230 degree hydraulic cam will have the same power band as a 240 degree solid lifter cam. At least that is what Ive been told in past conversations with various cam grinders.
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Old 02-02-2005, 08:26 PM
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Good points

I have to agree with all of your points about a roller cam. From his original post he stated he was building a "hot" motor, perhaps a weekend cruiser/strip ride.

I would never put a solid roller in a daily driver or touring type vehicle. In my opinion, it would be only for a mostly strip car.

Idling is such a problem for solid rollers because the mondo springs used build up heat really quick. Most people running any sort of endurance applications with a solid roller run oil spraybar valve covers to keep the springs cool.

Retainers and such don't last real long either. However, I have heard the new street rollers have better durability, although I have to say I don't have experience driving them on the street for a long period.

For a heavily modified motor looking to rev, solid rollers are the answer. For anything else, they are a hassle. Remember that solid lifters always have a "tick" to them, that can drive some people nuts.

About the lifters, word among the oval track community says the Crowers are a good "cheap" choice and the Iskys better but in the $700 range. Jesel Ultralights are the best but real pricey at $1500+ a set. The jesel have all the best features, coated aluminum/steel bodies, direct pin oiling, etc. but you really pay.

For a street car that isn't going to rev high, I would just put in hydraulic roller cam. Their durability is proven in OE applications and I don't like to worry about breaking in a flat-tappet.

Andy
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Old 02-02-2005, 08:27 PM
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solid vs hydraulic

As for maintainance and adjustment, while never having an engine around long enough to require readjusting the lifters, I have put in excess of 50,000 miles on a couple engines with solid lifters, and only then did I ever have to check the lash on them.
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Old 02-02-2005, 09:03 PM
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Well, contrary to most folks experiances I've had good luck with the two engines I've built that used solid roller cams. Granted the lobe profiles were very mild and the lifters had pressurized oil to the needle bearings.

Looking at the lift a 0.050 intervals versus duration at the same points, the cams I used were almost identical to hydraulic roller profiles from the same companies. One from Reed Cams and one from Lazer Cams, both custom grinds. The springs were only slightly stiffer than the springs recommended for most large hyd. roller cams.

The use of stiffer springs for an extended rpm range is the only real advantage that solid roller have over hyd. rollers on a street engine. If the revs are to be kept at 6200-6300 rpm I'd choose the hyd. roller. You'll make the same power without the worries of checking lash. If you intend to go above that and want ever available horsepower, solid roller cam will help you reach that goal. Be prepared to do the routine maintainence and don't use cheap parts or you will be sorry.

Above all, educate yourself before you do anything.

Larry
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Old 02-02-2005, 10:16 PM
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flat tappet solid vs hydraulic

If there ever comes a time when you decide to try to swap from a hot hydraulic grind to a solid with specs near the hydraulic you will definetely pick up bottom end and rpm at the same time.
Yes the hydraulic hardly needs to be touched, but the solids are also pretty trouble free if you stick with a modern profile that is street freindly. My BBC had run both a crower and a crane hydraulic and I was happy with them, but when I went with a solid crane blueprint version of the 396/375 I really noticed that the small rat woke up! In any event my .02 worth.
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Old 02-02-2005, 10:54 PM
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When I get rich I'd like to try these. Roller lifters with no needle bearings!

http://www.schubeckracing.com/new2/i...position=55:53

Larry
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Old 02-03-2005, 02:54 AM
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For that price they can keep them.
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Old 02-03-2005, 08:33 AM
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You would need to have a big wallet and a little one on the side to afford them. And hope the old lady doesn't find the receipt. Dave
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