Are Roller Cams Worth It?

[brianj5600]

I think that they are both only as good as the tuner. I have seen cars at the drag strip leave from idle and pull the wheels off the ground, I don't think they are giving much up in throttle response.

 

[68RCodeConv]

I can tell you the primary reason I went with a roller cam (solid) in my 347. Cam break-in and wiped lifters/cam lobes. Didn't want to waste a $5K motor because I wiped a cam lobe.

On top of that the roller lets me run a more aggressive ramp. 236/[email protected], .590 lift (.020 lash). Idles really well at 700 rpm (13 inches vacuum) and pulls to 6500.

I've got a 68 block with a custom ground cam (by Bullet) and linked solid roller lifters.

 

[mdjay]

I discussed my set up at length and in detail with Andy "the Butcher" Dunn and he opined that the roller cam I am currently considering would net me an additional 25 hp over what I have now.

Better understood!

 

[jerry S]

Better understood!

Andy just plain rocks. I sent him a one line email and he replied with a page after page analysis with links and attachments. He really took a lot of time to educate and help me and I cannot say enough good things about him. We then corresponded at length and he has shared so much knowledge and experience with me that I am almost a better person as a result.

 

[commonrail]

I have used both roller and flat tappet cams in my 351C motors. I have been successful with both. Both set-ups have definite advantages. I am currently running a hydraulic roller with EFI. I have more vacuum at idle with the roller cam. I had more peak horsepower with the hydraulic cam, due to turning the mill at 7400 vs 6500 with the roller. Average horsepower, and torque production is higher with my roller set! Some of this should be expected as a result of better engine building techniques, not just cam selection! I'm certain anyone's latest engine build is better than one done 10 years ago. As technology advances, we as a group advance (hopefully) !
The throttle response is better with the roller cam whether with carb or EFI ( I ran both on this motor). I can run higher lift and still have a decent streetable idle.
I liked the cost of the hydraulic flat tappet cams. I could own at least 3 or maybe 4 grinds to the one hydraulic retrofit kit. I am sorry this is a little vague, but I think much of this discussion is subjective opinion.
It all comes down to application. What will be your usage, do you need maximum power, or just a saturday night cruiser. You should plan how much use you will get from XXX horsepower, and be realistic. Are you really going to go to the track every weekend? If you are, then go for it. If is just for cruising, then you'll be more happy (reliable) with a mild-medium cam and a small carburetor.

 

[D.Hearne]

I believe there is at least one other benifit to having a roller setup, (reducing friction, increasing breathing), and that is an increase in responsiveness. I think in terms of how your car feels, that change can feel just as dramatic as an increase in HP. Hitting the pedal and having it push RIGHT NOW can be just as thrilling as extra HP's. In this case you may get some of both. Am I all wet or have any of you experienced this?

Any response gain from a roller over a flat tappet would be miniscule, and wouldn't register on the seat of the pants meter. The difference comes not from the friction reduction (there is some, just not as much as you'd think, as others have said here), the gain comes from the faster ramp profile possible with a roller. You get more area under the curve when relating to the time the valve is opened off the seat. Using a smaller carb also results in EFI-like response, and also using an EFI cam grind with less overlap helps too. I'm running a factory Ford F4TE hyd roller in the 5.0 in my Ranger and it behaves damn near the same as any EFI although it's carbed.

 

[Route666]

EFI is more responsive than a carb, but a hydraulic roller is not more responsive than a flat tappet hydraulic.

Don't roller cams allow faster ramps? Are the gains from having faster opening and closing and the same overlap and duration not worth it? They should allow better breathing but maintain more low-speed response than a similar-flowing flat-tappet cam with more duration / overlap right?

EDIT: - I just noticed D.Hearne just explained all this in the previous post.

Also I thought I might add in this nice idea I came across:

Roller lifters with no axle or roller bearings, runs like a plain bearing - floats on pressurised oil like mains and rod bearings. I'm not sure if they work that much better as they're made out though...

http://www.schubeckracing.com/rollerxb.html

Anybody tried them?

 

[Hack]

Don't roller cams allow faster ramps? Are the gains from having faster opening and closing and the same overlap and duration not worth it? They should allow better breathing but maintain more low-speed response than a similar-flowing flat-tappet cam with more duration / overlap right?

EDIT: - I just noticed D.Hearne just explained all this in the previous post.

The motor may have more power throughout the RPM range, but that is different than responsiveness. If you're going to define responsiveness as having more power, then anything that adds power adds responsiveness. You could also remove weight from the car and that would add responsiveness.

I always thought responsiveness meant the amount of time between a throttle input and an engine response and/or how fast the engine will rev without any load. Totally different. For instance a tunnel ram set up would have less responsiveness than a low rise intake because it takes longer for the increased fuel/air mix to get to the cylinders after stepping on the loud pedal. Or people use a light weight flywheel or remove mass from the rotating assembly to increase engine responsiveness.

edit: for example, I once had a Quadrajunk carb in a Generic Motors product that had really bad bog. If I floored it from an idle, the engine would bog for a second or maybe more - then it would finally take off. That's bad responsiveness.

 

[BlueMonster65]

ok, after reading this post i feel compelled to help or thouroughly confuse.
the roller cam allows for much greater HP and tq because of the more agressive ramp profiles possible. an engine is considered near zero friction anyway because of the oil. using an engine building program such as desktop dyno one can see that roller cam engines generate much more torque at lower rpms with relatively moderate profiles. also low manifold vacume levels are not a problem even with profiles that would be considered unstreetable for flat tappet cams. however, it is most cost effective to use a 5.0 roller block vs. converting a regular block.

and as far as carbs go, do not underestimate the efficiency and superior performace capability of the simple carb. expensive FAST efi systems do a good job of adjusting a/f on the fly. but factory systems such as the ford eec V are not very good. understanding how to tune a holley DP carb is easy and cheaper than any EFI system.

 

[Route666]

The motor may have more power throughout the RPM range, but that is different than responsiveness. If you're going to define responsiveness as having more power, then anything that adds power adds responsiveness. You could also remove weight from the car and that would add responsiveness.

I always thought responsiveness meant the amount of time between a throttle input and an engine response and/or how fast the engine will rev without any load. Totally different. For instance a tunnel ram set up would have less responsiveness than a low rise intake because it takes longer for the increased fuel/air mix to get to the cylinders after stepping on the loud pedal. Or people use a light weight flywheel or remove mass from the rotating assembly to increase engine responsiveness.

edit: for example, I once had a Quadrajunk carb in a Generic Motors product that had really bad bog. If I floored it from an idle, the engine would bog for a second or maybe more - then it would finally take off. That's bad responsiveness.

I didn't define responsiveness as more power, in fact I thought of it as you do. Have another look, I basically said what you did.

The advantage I see of the roller cam is the ability to maintain responsiveness (by not having too much duration and overlap) while allowing better breathing through the valves spending more time at full open than a flat-tappet cam with same duration and overlap. These things - power and response are usually mutually exclusive, because more breathing used to mean more duration and overlap which kills low-speed intake and exhaust velocity - leading to less air-fuel in the cylinder at low speed. Faster opening and closing gives more of BOTH.

What I'm wondering is if the benefits of the roller ramps is in the 2% or 20% range of "better" than flat-tappet.

 

[Hack]

I didn't define responsiveness as more power, in fact I thought of it as you do. Have another look, I basically said what you did.

The advantage I see of the roller cam is the ability to maintain responsiveness (by not having too much duration and overlap) while allowing better breathing through the valves spending more time at full open than a flat-tappet cam with same duration and overlap. These things - power and response are usually mutually exclusive, because more breathing used to mean more duration and overlap which kills low-speed intake and exhaust velocity - leading to less air-fuel in the cylinder at low speed. Faster opening and closing gives more of BOTH.

What I'm wondering is if the benefits of the roller ramps is in the 2% or 20% range of "better" than flat-tappet.

Ok, gotcha now.
I personally really like rollers for a couple non-performance reasons.
1. Modern oils don't have the additives that flat tappets really like for the best lubrication (although you can get Shell Rotella T as an alternative).
2. Worries about wiping the cam during break in.
3. The roller is the current hot set up, and it's easier to find a deal on one if you go to a roller block. The late 80's roller motors are really easy to find now-a-days for builds.

 

[Route666]

I personally really like rollers for a couple non-performance reasons.

I agree with those, the roller definitely is an improved solution. Cam break in has always worried me a little - something about revving a brand new, cold, unloaded motor gives me the willies.

 

[65ShelbyClone]

1. Modern oils don't have the additives that flat tappets really like for the best lubrication (although you can get Shell Rotella T as an alternative).

3. The roller is the current hot set up, and it's easier to find a deal on one if you go to a roller block. The late 80's roller motors are really easy to find now-a-days for builds.

1. Not just Rotella, but pretty much all the oils for diesel trucks. 4-stroke bike riders like me would rather get a gallon of it for the same price as a quart of bike oil. It has more zinc and less molybdenum. However, engine oils are vastly better than they were in the flat cam era so I wouldn't be concerned with one wearing out faster. Think about how many OHC engines these days run cam-over-bucket lifters or slider-type rockers.

3. The good thing about the roller blocks is that they were used from 1984 all the way until the 5.0 Explorer got a modular, I think in 2002. There are a lot out there and even though Ford quit building them, you can still find new bare blocks. That's what is in my '68.

Just FYI.

 

[bad68coupe]

an engine is considered near zero friction anyway because of the oil.

the coefficient of friction for metal on metal with lubrication is still very noteable.