Roller cam idea that I'm rolling around in my noggin....

[lilcuda]

Oh boy, here we go again! "I've heard" is not a good enough reason to diss possibly the best selling line of camshafts and related components on earth. Take a walk through the pits at any NHRA event and talk to the racers and engine builders attending. Sure, now and then you're going to hear a negative comment but who knows how the engine was built, broken in or treated? Do the same at local bracket races where a lot of street cars show up. My experience, both for my cars and those I talk to have been overwhelmingly positive when dealing with Comp Cams. And certainly, get professional opinions from all brands that interest you.
I don't want to say you don't have a right to your opinion, but "I've heard" is so not that...

Not getting into a pissing contest over this, but do you really think that Joe Shmoe who buys an off the shelf grind from Summit gets the same quality components as a racer or engine builder with big time sponsors and a well known reputation?

I have a friend who runs a performance shop in NC and his engine builder doesn’t use Comp anymore.

It’s all over many of the car forums. Do you think people are making it up?

 

[Kern Dog]

Since Comp Cams sells about half of the aftermarket cams we all buy, they will be the name that gets mentioned the most for every issue, good or bad.

 

[Geoff 2]

^^^^^This. More sold, more failures. It is all about percentages.

 

[PsyOps]

I spoke to my cam grinder & machinist. Both said the problem lies at the foundries where the cam cores are produced. Second cause, in their opinion, was lifter failure which many novice builders blame on the cam. I agree with the statement that Comp (and the smaller cam companies they run) sell more cams to the common public than everyone else so the failure rate may be equal in percentages to the other companies. Plus, there is no way to determine if it was a parts failure, bad installation, poor break-in, low oil, or a myriad of other problems that caused the cam to fail. I too have listened to the "I heard" crowd but no one (that I know of) has produced a comprehensive report across the cam community to bear out the negative statements. Use Comp or don't, I don't, but that's what's great about this country - freedom of choice. To the OP, my performance machinist opines for a hyd roller for mostly street driving under 6500.

 

[rikkitik]

Just my 2 cents, but cam manufacturers notwithstanding, it's important to understand why your current cam isn't performing as you would like.
While the cam is a bit on the large side (duration wise), it also appears to be an older design. The "advertised" number is very long, particularly for that lift.
Some quick calculations with that duration and installed CL, gives an intake closing point of 84 degrees ABDC. Then the 9.8 compression, and you're at about 125lbs cranking pressure (6.5:1 dynamic CR). You are simply bleeding too much compression.
Remember, you can't build cylinder pressure until the intake valve is on the seat.
With a "street" engine, ALL duration numbers are important, advertised, .050, AND .200 (regardless of manufacturer).
I like Bullet/Ultradyne myself, but there are plenty of others too.
For me, it's important to talk to the right "tech" on the other end of the phone. Unfortunately, (in my experience Comp, Howards, Lunati) it's kind of a "crap shoot" who you talk to.
Tim Goolsby (at Bullet) is super sharp, and tremendously helpful (patient) in his explanation, and recommendations.
As someone previously mentioned, SFT should be quicker off the base, but roller allows more ramp velocity after the base.
I'm just running a crummy little 440 (w TF240's, and 9.8:1), with an SFT Ultradyne profile. The "tale of the tape"....adv. 270/274, .050 243/247, .200 162/164, lift (w/1.6) .584/.596 108LSA, 104 installed (thats quicker than a lot of HR's).
But a solid roller will certainly go into it's next "iteration" (plus cubes).

 

[Kern Dog]

This same cam was used in my engine awhile back with 10.18 compression, advanced 4 degrees and gave cranking compression numbers in the mid 160s.

 

[rikkitik]

A slightly shorter. 050, (and a lot shorter advertised) 110 LSA, in at 104 CL would probably make you much happier.
Getting up around 170/175psi will sharpen response and still be liveable with California "gas".......

 

[Kern Dog]

Currently, I have a vacuum pump to provide enough power to run the power brakes. The last time I used this cam, I was running a bit more compression but the idle vacuum was too low.
The '528 cam actually made a LOT more idle vacuum...enough to power the brakes without the vacuum pump.
I'm interested in knowing if a powerful roller cam arrangement could provide enough vacuum to run without the vacuum pump.

 

[mentor70]

Kern, I've read your exploits a few times, I also live in California, LA for 23 years, built a 496 in 2000 for my Cuda, I started the build in Salt Lake City, Utah where I'm originally from...at over 4000 ft above sea level, building a high compression pump gas engine is something seldom second guessed, but I got schooled when my 11.6 to 1 engine came to life at 800 foot elevation...91 octane???....NOPE! Cam was a good street choice, but too small for the cylinder pressure...ended up selling the whole car...new owner immediately put in a cam similar to what you have now, and with some distributor work and carburetor tuning, got it usable. ..

I'm currently doing another 496...same pistons as your currently using, but with Trickflow heads...I have a hand full of cams I could use, and my car has no power anything so not too worried about manifold vacuum...but I am concerned about engine optimization.
So with this in mind, if I were you, I would first see what your cranking cylinder pressure is, before any cam selection is made.

My guess is that you are in the low 150s now, but Id definitely be interested to see what is really going on.

One of my cams is the Trickflow hydraulic roller cam, it's.243 at. 050 and .600 lift.

It's designed around a 10.1 compression, so it would probably work well for my setup and probably yours too...cylinder pressure IMO should not exceed 180 psi, preferably a bit less. Maybe 170-175 for 91 pump.

 

[Kern Dog]

Years ago, I had a combination that I was told would be street friendly.
It was NOT.
10.8 to 1 with Edelbrock aluminum heads knocked with every cam I used including the famous MP '509, the Comp Extreme Energy 545, This Lunati too.
I had as much as 180+ cranking compression. A switch to thicker head gaskets dropped compression to 10.1 and those numbers to the 165 range. It was then that I was able to drive it with 91 octane with no detonation.
At 9.8 with quench and dished pistons, I haven't knocked at all.

 

[Cranky]

Years ago, I had a combination that I was told would be street friendly.
It was NOT.
10.8 to 1 with Edelbrock aluminum heads knocked with every cam I used including the famous MP '509, the Comp Extreme Energy 545, This Lunati too.
I had as much as 180+ cranking compression. A switch to thicker head gaskets dropped compression to 10.1 and those numbers to the 165 range. It was then that I was able to drive it with 91 octane with no detonation.
At 9.8 with quench and dished pistons, I haven't knocked at all.

What was your quench distance with those other cams?

 

[Kern Dog]

It varied a bit but started out with a deck clearance of .017 and a head gasket of .039 compressed. That is .056 right there. Later after 2 cams went flat, I pulled the engine, honed and re-ringed it, had the heads gone through and had a slightly smaller chamber size and .012 deck clearance. Then I was at .051 "quench".
It was not optimal. Cranky...YOU were one that advised against me using thicker head gaskets to lower compression based on the history of how mid 70s 400s and 440s had no quench and still detonated.
Somehow, the thicker head gaskets actually did stop the detonation for me but I knew it was a band-aid. The proper choice was to use dished pistons with quench pads like these:

These very pistons are in the engine now.

 

[BSB67]

I'm interested in knowing if a powerful roller cam arrangement could provide enough vacuum to run without the vacuum pump.

Yes.
But there are at least two caveats:
What is powerful to you?
You cannot have your cake and eat it too.

Think of a roller cam the same as any other cam. They can be as mild or wild as you want. With that there is also a continuum of how hard they can be on valvetrain parts (agressiveness) . Furthermore, how hard they are on parts is not a function of how big they are. So it is a three way balancing act. Idle/low speed quality, power, agressiveness (i.e. hard on parts).

Comp Cams has about 100 solid roller cam lobe families (design characteristic). Each "lobe family" probably average 20 different lobe sizes (smaller to larger). Generally, the lobe family (design) dictates the aggressiveness of the lobe (i.e., how fast it moves the valve).

Here is a way to maybe think about lobe agressiveness. You can have two solid roller cams with 0.580 valve lift (assume 1.5 rocker). One cam is less aggressive and you can use valve spings with 160 lb seat pressure and 400 lbs open pressure. The other cam is aggresive, and requires 250/600 pressures. The same analysis goes for duration too. You can have two solid roller cam with 244 degrees duration @ 0.050". But one can use the 160/400 spring, the other will need the 250/600 spring. The cams that will idle the best in these comparisons will be more agressive lobes and require the higher valve spring pressures, but will make more power.

So, you can have a solid roller that will give you similar idle vacuum as the MP 528 that makes a little more power, or one that makes a lot more power (and everything in-between). Obviously, the higher power making cam will be harder on parts and require greated valve spring pressures.

The cam that I recommended in my earlier post is what I'm guessing would be a good balance for you. It will definately idle way better than your large solid cam that you have now, but not as good as the MP 528. It will likely make more power than your larger cam, but will tolerate a less valvespring pressure and won't be too hard on valvetrain parts. But this is just my opinion on what might work for you.

 

[Kern Dog]

Thank you, BSB. I appreciate the helpful advice.

 

[beanhead]

I've been pondering a roller setup for my next buildup as well. I've also learned they aren't infallible like popular wisdom says, and have seen a few wiped rollers up close. Some were factory parts, LS and gen3 hemi.
Here's the first few of the many pictures that came up on a gaggle image search of "lifter failure". Ouch!

 

[Kern Dog]

I run a Howards .545 lift, 234/241 @ .050 hydraulic roller in a 505. Absolutely love it! It makes great power but has good street manners, too, and is super quiet. It's been in for over 7 years now and virtually no issues.

I came back to your response now and am curious.
I'm curious about the idle quality, vacuum and a few other things.
What RPMs does it feel like is the peak? Is your setup somewhat maintenance free? What did the setup cost for the cam and lifters? I'd love it if you could elaborate a bit more, thanks.

 

[gkent]

Go ahead and laugh but ... when I was chosing my can I ran the various choices through "Desktop Dyno". Prior to doing that I decided on what gear I was running and what sort of bottom end torque I was looking for. With that as my target I plugged in all the various engine info then ran the numbers and graphs for each cam I was considering. If you're any good with Excel you can plug all the numbers in there and do a graph showing all of them. Keep in mind that unless you have a very common engine build most opinions are going to be just that. Desktop Dyno may not be perfect but I figure its margin of error would probably be the same for each combo so its still comparing apples to apples.

 

[Kern Dog]

KD, I have run a solid roller cam in my 500 motor. But my motor is too different from yours to recommend it.

You didn’t ask for opinions, but I’ll give one. For your application I would recommend the Comp Cam’s Extreme Energy solid roller. It is advertised as a street roller, but it’s no lollipop either. It’s the XR286R. It 286/292 advertised and 248/254 @ 0.050. I think you’ll be close to 0.600” lift with the 1.6’s.

Let the fun begin

Interesting. Some others have suggested a solid roller as well.
Here are the specs on my current camshaft:

I don't think this is soft on the bottom end but it did seem like the MP '528 solid I ran before was a bit more peppy under 3000 rpms than the Lunati.
You asked about what I consider "powerful". I wish that I could define it. Some would do so by posting an ET goal or rear wheel HP. I don't drag race but I'd like to some day. In the meantime, I want the most power that the engine can make while also having more idle vacuum. I wasn't disappointed with the 528 or this Lunati in regards to power but more is always welcome. The Lunati doesn't idle that bad...I have a 5 speed so it isn't as if I'm idling in gear at stoplights. I recall being able to accelerate in 5th from 1000 rpms with the MP 528. The Lunati doesn't do that as well!
I'm drawn to the roller cam idea partly from what I have heard about them. Correct me if I have it wrong but I thought I've heard that the proper grind can run as strong as a flat tappet but idle better and make more vacuum. To me, that is a great advantage.
I'm sure that I can do just fine with a milder cam.

 

[JC Boatguy]

I was able to talk to an ACTUAL engineer at Tri Star motors. We buy almost all of our Inboard marine engines from them. I told him of a 440/505 I am building and I really wanted to run a vacuum advance and a power brake booster. He made it clearer to me than anyone else could.

Here is his advice...you have to keep the intake duration in the 220s @ .050 in order get good idle vacuum. Just look at Cams or custom grinds that play with lots of lift, but keep the duration down.

 

[Cranky]

I was able to talk to an ACTUAL engineer at Tri Star motors. We buy almost all of our Inboard marine engines from them. I told him of a 440/505 I am building and I really wanted to run a vacuum advance and a power brake booster. He made it clearer to me than anyone else could.

Here is his advice...you have to keep the intake duration in the 220s @ .050 in order get good idle vacuum. Just look at Cams or custom grinds that play with lots of lift, but keep the duration down.

And ya gotta pay attention to the valve events with cams with shorter duration or you could end up with too much cylinder pressure in the lower rpm ranges. I 'learnt' about that many years ago and Engine Masters did a show recently about that and dynamic compression. I did a Ford big block where the guy wanted this high lift cam but was short duration....don't remember the @.050 numbers though but questioned it and he said he already talked with someone about it and said to run it and even told me to set it up according to the cam card. The biggest problem was his static compression was a bit over 10-1.....and it fried a couple of pistons even though he had a retard setup on it.