Would there be much advantage running a solid flat tappet cam with 224/230 duration as opposed to a hydraulic roller cam?
The exact cam is 230/236 110*LCA 268/274 .489/.503 solid flat lifters. I'd like to run it with 1.6:1 rockers though. The roller is the XE224/230HR by Comp.

I'm not that concerned about the extra maintenance... if that was the case my vehicle wouldn't have a carb on it!

I'm wondering now... If I am swapping out my hydraulic flat tappet 212/222 112LCA for a hydraulic roller... if I just shouldn't go for a solid cam.

I'm not looking to make a lot of HIGH end HP, I'm looking at the swap for more torque. Looking to maximize area under the power curve. I want to spin it to 6000 RPM max.

What do you guys think? If you're reading this thinking that it's honestly not worth the gains being that we are talking about mild solid cams... LET ME KNOW!

Looking for a lot of torque to get a heavy vehicle moving.

I really don't know why I've been scared of solid cams. I think I'm staring to like them!

I'm not completely opposed to a solid roller either. I'm really liking the mild 230/236 268/274 .522/.564 with 1.5:1 rockers and on a 110LCA. Comp says it's good for power in the 2000-6000 rpm range, but from what I've been reading solid cams with short durations should be ran as solids and not mechanical rollers. The solid flats are lighter and although the rollers are heavier, they are better suited to long duration numbers. I really don't want to run that much duration anyway, and I'm not going to need a whole lot of torque. The roller would be harder on valve springs too as opposed to the solid. The roller parts are also WAY more expensive.

If anyone is wondering which heads I am running they are the GM vortec heads. They are as cast now, but when they come off to be machined for the new springs they will be ported. Compression is to be 9.5:1. Gearing is 3.42:1 with a 2.48:1 first gear. I will run a dual plane intake on it. A modified 750cfm Holley is going to fuel this combo.

As I'm sure everyone knows the xe268 (hydraulic flat tappet) is very powerful when teamed up with the stock vortecs and makes good power... to the order of >400hp at the crank.

I believe the solid will out perform the hydraulic flat, but I want to know how the light weight solid lifters and matching cam would compare to a late model (and maintenance free!) hydro-roller.

This vehicle is driven daily 50 miles and good economy is important. Weighing in at 4200lbs I need the most torque available. Please advise me. Some of you guys have been building engines longer than I've been alive.


Ben T.

 

It's difficult to compare solid lifter cam specs to hydraulic specs- let alone flat tappet to roller all at the same time. I'll make a few generalizations.....

For a street (torque) engine I have long been a fan of flat tappet solids. Not becuase you can't beat them with a roller but the bang/buck is much higher with a flat tappet cam in this area. Roller cams really shine when you have high flowing heads and other stuff that can really BREATHE when the RPMs come up. When you get down into daily-commute RPM range and start talking about short duration cams my personal opinion is that they just don't help enough to justify their cost (which can be substantial to convert an earlier engine to a roller cam).

I am SURE there will be a line around the block waiting to disagree with me on that but I've been building dirt-cheap street engines for a while and I never felt like I was missing much by never using a roller cam. None of my friends who I built motors for did either.

One critical thing to remember when looking at the specs on a solid cam- ANY solid cam. It will act "smaller" than the specs would otherwise indicate. Remember that a solid cam has a "lash" spec. On a typical flat tappet solid cam that's usually around .022-.025" or thereabouts. The first thing that does is to subtract that amount directly off of the max lift number. In your example, starting from a max intake lift of .477" subtract .025" lash from that number and it's down to .452" lift at the valve. ALSO, the lash shortens the EFFECTIVE duration of the cam. I won't go into all the whys and wherefores but subtract about 5-6* from the .050 duration numbers and that's about what the cam will effectively ACT like. 224* @ .050 starts acting more like a sub-220* cam. Suddenly that 224* duration solid cam doesn't seem very big, does it?

In short- don't compare .050 duration numbers or lift numbers directly between a solid cam and a hydraulic cam. It's almost apples and oranges (not quite, but close).

As for running solid lifters on a hydraulic cam of any kind..... you're on your own on that one. I have not done it so I won't comment. Sounds like asking for trouble to me.

 

Solid lifters on a hydraulic cam!? Did I say that? I didn't mean to. PM the confusing part in my original post to me and I'll fix it!

Well, I actually knew that you subtract around 6 degrees of the @ .050 lift if you want to dare to compare duration, BUT I had forgot about the lift and lash. Now, I'm not just saying that... honest. I know some people do that sort of thing. I really did know this!!!

So, you have to subtract the "vavle lash" from the advertised lift number of the camshaft, and that will give you the effective lift. Thanks for reminding me of this.

Okay, guys. School is over for the week, and my gf is out of town... so I'm done a little figuring. Let me know if any of this is off track, ESPECIALLY THE LIFT NUMBERS @ .200".

Here's some camshaft lobe info. All of this comes from the Comp Cams website,

http://www.compcams.com/Technical/Ca...L/238-273.html .

Here's the information I've come up with lately trying to see what's best for a short duration engine seeking to make a lot of torque.

If I understand correctly, hydraulic rollers off improved ramp rates, BUT initially they are slower getting the lifter up on the lobe then a hydraulic flat tappet and way slower than a solid lifter. So, with this said here is my 'numbers'

lobe type adver .050 .200 lobe valvelift
5443 hyd,f 268 224 137 .318 .477
5445 hyd,f 274 230 143 .325 .488
3314 hyd,r 276 224 145 .335 .503
3315 hyd,r 281 230 151 .340 .510
6053 soli,fl 262 224 135 .319 .479 .511-lash
6054 soli,fl 268 230 141 .326 .489 .522-lash
6055 soli,fl 274 236 147 .335 .503 .537-lash

Whew! So, here we go. Now, wanting to keep economy up and wanting to make as much torque as possible I want to run the least amount of advertised duration as possible. After all, when ever you figure out trapped/dynamic compression ratio you use advertised duration, right!? So, according to the data I have presented it seems that the solid lifter lobes win hands down, but I think it's a little bit more than this. Now, the extrem lobes that comp has recently came out with use fast ramp rates with provide for wide .050" numbers and lowadvertised duration numbers. The cam I would interested in running would combine the 6054 & 6055 lobes. When you take away 6 degress from their .050" numbers, low and behold, they seem to be the exact same as the Extrem Hydraulic flat tappet specs.

224/230 VS. 268/274
224/230 VS. 268/274

So, those numbers are the same. Next, we can go further by looking at lift at .200"

137/143 hydraulic flat tappet
141/147 solid lifter.

Now, we see that the solid lifter cam has more lift up high. This would make the hydraulic flat tappet shaped more like a Christmas tree compared to the broader solid that would be shaped more like an umbrella.

Now, this seems like where the solid cam would win! The only thing is I don't know if there is an accepted norm for comparing the durations at 1/5 inch lift.

***So, if someone could chime in and help me out. I'd appreciate it! Join me in some speculation/entertainment***.

If you compare where Comp says the cams make best power from their theory whatever it may be you also find interesting information. The solid lifter cam has the biggest 'powerband'. It makes power soonest and makes it the longest. This comparison uses a solid cam with 6 degrees more duration on both sides than the hydraulics do.

For your review (all based on the SAME LCA),
1600-5800 RPM Hydraulic flat tappet
1900-5600 RPM Hydraulic roller
1600-6000 RPM Solid flat tappet

This makes for 'power bands' of
3700 RPM Hydraulic roller
4200 RPM Hydraulic flat tappet
4500 RPMSolid flat tappet.

This information is probably all theoretical, but comp cams published it in the catalouge. I would say the reason why the hydraulic roller has a narrower operating range is because of the extra advertised duration it packs. This bleeds off a little more pressure and such cam timing doesn't do well until apparently 1900RPM. Now, remember, I'm looking for max power on the street with best economy. This would seem to look like the solid cam wins again, but the hydraulic roller may be a player too. Even though it is lazy getting the valves open, it has roller needle bearings and could be run with a higher static compression ratio than the others. ***So, that is another topic I'd like to get some input on. Please speculate with me.***

One last thing that I want to point out is some info from the same engine but with different cams. Same engine with 224/230* specs first set of numbers is from a hydraulic roller second set is from a hydraulic flat tappet. This is a 9.25:1 357ci chevy with a dual plane on it:

Max Torque 427 ft*lbs @ 3700 RPM Max Power 373 HP @ 5200 RPM
Manifold Vacuum 12" Hg @ 800 RPM & 14" Hg @ 1000 RPM w/ no load.


Max Torque 413 ft*lbs @ 3800 RPM Max Power 342 HP @ 5000 RPM
Manifold Vacuum 15.5" Hg @ 800 RPM & 17" Hg @ 1000 RPM w/ no load.


First off, this contradicts the above info that comp published that said the hydraulic roller likes to rev higher than the hyrdraulic flat tappet. That's not that important though. Now, examine the difference in vacuum. Looks like that hydraulic flat tappet makes more vacuum and I would speculate would be more efficient at idle and at cruise speed. The roller does make 30 more hp than the hydraulic flat tappet does. When you go back up and look at the duration figures (we really can compare these) I would think by looking at the duration at .200" the hydraulic roller would have done such. It also makes more lift too. So, clearly the hydro-roller makes more power, but at the cost of how much efficiency I don't know.

Unfortunately, I don't came the same information for the xs268r cam. Wish I did! That would make it easy.

So, here's where I need some input! You guys (or girls?) tell me what you think. Talk to me from your experience building engines... I've never built one, BUT if I keep this up my first one will hopefully come out well when I start modifying my 350HO chevy crate engine.

I've also included lift numbers with 1.6:1 rockers in that first 'numerical cluster'. Anyway, tell me you guys think.

The hydraulic flat tappet has made ~400hp with vortec heads. If we add the same 30hp to this number that was added earlier... this would be vortec heads and XE224/230HR makes ~430hp. That's starting to really look nice, huh?!

Skim though all of that 'stuff' above or digest it, but you guys help me out. I'm trying to do my homework, but I want some help. If you make a post you could consider yourself my "tutor".

The information about the hydraulic flat tappet is there to aid in the decision to go with the hydraulic roller or the solid tappet cam. So, I would either do the XE224/230 276/281 .503/.510 or I would do the XS268S 230/236 268/274 .502/.517 (that's lift with 1.6 rockers and -.20 for lash). Again, looking for max street power and highest miles per gallon.

If you bore with me and got this far down... thanks!

Ben T.

 

I would first start from- what kind of cam does the motor have in it right now? If it's a flat tappet the conversion cost of the roller lifters, spider, possibly machining the block, machining the heads for bigger springs, shorter pushrods, etc. can add up quick. If this is your first motor I wouldn't recommend diving stright into a roller cam conversion. If the motor already comes with a roller cam (don't know if the 350HO does or not) then buying an aftermarket replacement for it would be much more stright-forward and might be worth doing. Whatcha starting with (engine and cam specs)?

 

For those who don't know this engine,

http://www.sdpc2000.com/cart.asp?act...id=120&pid=462

That's the one that's in there. Cam specs are 212/222 on a 112LCA lift comes in at .435/.460 and this is a hydraulic flat tappet cam. Damon, this is the revised GEN I block with the 1-piece rear-main seal and provisions for the factory roller cam.

I actually have 95% of the hydraulic roller cam parts already. I don't have the springs or the spider, but I have all of the other parts; retainers, lifters, pushrods, etc. Oh, and I'd need a timing set too. Exclude the cost of the head work too. We'll call that 'free' in the analysis. I wouldn't mind doing the roller, but if I can find more street performance with the same economy I'm willing to go solid and adjust some valves once in a while and change a $50 set of springs every two years.

Daman,
I'm ready to hear why! Would you explain this to me. Exactly why, is what I am looking for.

Ben T.

 

Whew!

Lots of reading there.

Thoughts:

For low-mid range torque you really can't tolerate much overlap.

If rpm is limited to 6000-6500 or so, HR works fine if you use the correct valvetrain bits.

If you use aggressive HR lobes they have very good initial lift (velocity actually as in inches of lift per degree of rotation). They will get you where you want to go, and with relatively short durations give minimum overlap, and therfore maximum idle vacuum and low rpm grunt.

One of the problems with SR profiles is that there are not many good, agressive ones below 235* or so @ .050.

IMO, you will get close to what you want with a lot less than 235* if you use the correct aggressive HR. A comp 3190/3192 comes to mind on something like a 110 LCA. This is a 214/224 cam with a LOT more lift than your flat lifter. It may even be too much for the Vortec heads and a "softer" HR grind will probally be better. Get professional advice on cam selection.

The exact specs should be determined base on the entire engine and vehicle combination. Getting a couple of tons moving is the problem.

My $.02

 

Ben, for similar reasons to why you subtract lash from max lift on a solid it also shortens the EFFECTIVE duration. On a hydraulic you have zero lash. .050 at the lifter all goes straight to making the valve move (theoretically, .075 at the valve with 1.5 rockers)

On a solid .050 at the lifter does NOT all go to moving the valve. The first .022 lash at the valve (therefore .015 at the tappet, assuming 1.5 rocker arms) goes strictly to taking up the play in the valvetrain. Only once you have taken up the lash does the valve start to move. In this example you wouldn't be moving the valve at all from 0 to .015 tappet lift and THEN the valve would be moving from .015 to .050 tappet lift (for a total of only .035" effective tappet lift, i.e. actually moving the valve, at the stated .050 lift point). You'd have to be at .065 tappet lift before you got to the same .075 valve lift as the hydraulic cam from the previous paragraph (again, assuming theoretical 1.5 rockers)

Why? Because on all cams .050 tappet lift is measured at just that- .050 tappet lift. NOT .050 OVER LASH SPEC.

Net effect is that it shaves off a few degrees of effective duration on both the opening and closing side of the solid's cam lobe. Net net, 5-6* less effective duration, give or take as a rough rule of thumb. I'm sure some really smart person could do the math and come up with a really accurate number but this will get you in the ballpark.

Next question- can you increase or decrease a solid cam's effective duration by tightening or loosening the lash? You betcha. Racers and sharp street tuners use this as a fine-tuning aid all the time.

 

Hey guys just reading through the post and thought I might have some info that would intrest some people. I have a lt1 motor and am running the comp 306 cam and had comp pro mag hydralic roller lifters. After floating two lifters I talked with a local speed shop and we called crane. They sent me a set of soild roller lifters to fit the block and told us to run the lash about 4 to 6 thousands. I know this might sound weird I didn't know that you could use soild roller on hydralic roller cam but this does work and the car sounds better and I don't have to worry about floating the valves out. Just wondering if anyone else as tried this.

 

Good reading / learning here in this thread.
Thanks for the education.

Damon, can you shed any light on this last question by jonesy?

 

I've heard of a few people doing this. You have to run real tight lash because a hydraulic cam doesn't have "lash ramps" ground into the cam profile like a solid cam does- it starts lifting in earnest right from the get-go. I know one persona who's running .002" hot lash on a setup like this. I have not done it so I can't really comment. I don't have the money to build "Frankensteins" like that and take the risk. I stick to known-quantity valvetrains.

I would think that a hydraulic roller, if matched with the correct valvetrain parts and assembled correctly should work just fine with hydraulic roller lifters it was designed to use. I have a feeling that dropping in a set of solid roller lifters is a kind of "crutch." It's STILL going to encounter valve float, but there's just no hydraulic lifter to "pump up" when it does.

 

Thoughts:

.002 "hot lash" sounds tough to get with engine at operating temp.

When engine gets hotter than lash temp, won't valves start to stay open slightly? How will exhaust valve then transfer heat to seat?

I'd worry more about closling/bouncing than opening.

Cam/valvetrain designers spend lots of $ and Spintron time trying to get compatible valvetrain pieces. Playing mix-n-match sounds like a dangerous sport to me. I agree with Damon.

How about the opposite approach if you are restricted to using hydraulic lifters: reduce travel of lifter to a couple of thou, and run SR cam. Not a new approach.


My $.02