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Roller Cam question

15K views 23 replies 9 participants last post by  The Mad Porter 
#1 ·
I was only able to find a couple threads on roller cams using the search function. It seams the few that are here do not promote the hyd roller lifter conversion due to push rod angle if I understood them correctly. So my question is why would the push rods be at a different angle? The roller lifter will be taller and heavier but should still be in a straight line, right? Any other concerns with a roller cam conversion? besides the cost...
 
#2 ·
The pushrods angle in different directions because the valves are canted.
I run a hydraulic roller cam, and would not consider running anything else (price not considered). No break-in concerns, can swap cams without changing lifters, etc.)

I don't have a photo showing pushrod angles, but in this photo you can see the angles by looking at the rocker arm stud angle.
 

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#3 ·
I get that the valves are canted but they are in the same spot regardless of how long the push rod is. Why does a taller lifter/shorter pushrod change the angle? The lifter and pushrod are still in a straight line to the rocker aren't they? Or is it because of the arc the rocker arm moves on causes the pushrod angle to change during the cycle because it pivots higher? I think I answered my own question...
so if that's the case, did you have to modify the guide plates to use roller rockers?
I know the cost is 6-700 bucks for cam and lifters but I think my next cam will be a roller if there is no concern mechanically. My car is a daily driver (mostly) and needs to be reliable over the long haul.
 
#4 ·
tHE PUSHROD is not square with the rocker arm and not with the lifter like a inline engine. The hyd roller lifter measures about .600 taller than a flat tappet this increases the angle of the pushrod which increases the angle it sits in the cup.
If I WAS TO USE A ROLLER HYD in a canted valve engine would keep the lift like no more than .550 for a daily driver.

Now the 351M and 400 had much longer pushrods more lift might do better.

The 460 was the only engine ford never converted to a hyd roller because of it. One inline engine the 2.8 V6 converted to HYD lifters the pushrods short length caused the pushrod to have a bad angle but they went with it i did the layout for it. Tried to get them to do it like the 4.0 which has standard height lifters although rollers. They sort of did a keyway in the lifter bore and a key jammed into the side of the lifter.
 
#5 · (Edited)
When the lifter plunger or cup are in the standard location the pushrod is in plane with the rocker stud / bolt and esentially perpendicular to the pushrod cup in the rocker. When you shorten the pushrod the .600" give or take the pushrod then comes out of plane and tries to side load the rocker arm wasting motion. Increased noise and wear result.

The only time I would use a juice roller and juice roller lifters is IF the rockers are factory bolt down stamped rockers, Yella Terra bolt down roller rockers or shaft rockers (spendy). These set ups resist the side motion generated by a short pushrod where a stud mounted rocker is pushed to the side until the pushrod contacts the guide plate.

What we have done to address this is to use solid roller lifters on hydraulic roller profiles. This offers the benefit of a roller set up without the short pushrods. In addition the milder spring pressures required by said profiles make the set up street friendly significantly increasing longevity. I have been both surprised and pleased with the results with 0 problems in the crate engines so equipped. Keep lash near 0 cold on aluminum heads and at about .006" cold with iron heads as there are no lash ramps on the roller profiles.

Pictured is my 750+ HP AFR headed 557. 255 / 268 hydraulic roller cam with solid roller lifters, AFR 300 heads and comp XD rockers.
Note how the pushrods are perpendicular or square to the rocker arm pushrod cup and in plane with the rocker studs.
If hydraulic roller lifters were in place in the pictures the pushrod ends in the lifter valley at the lifter pair cups would be closer together. This would then introduct angular potential at the relative location of the pushrod in the rocker cup forcing it to move to the side before transmitting motion to move the rocker arm's pushrod end vertically. Wasted motion...

Note that some inexpensive solid roller lifters have a higher cup location so pay attention.



S
 

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#6 ·
thanks guys! that helped a lot.
So if I decide to go roller, would y'all recommend solid rollers? I drive the car a lot with some weekend track duty. I don't mind pulling the valve covers once in a while to check/set the lash. I have the Edelbrock RPM heads and Comp Cams roller rockers. I guess the Scotty option would have the same geometry as a solid lifter if I understand the description.
 
#7 ·
Use good quality pressure fed solid roller lifters and set up the rockers at 0 lash cold for first start. Aluminum heads with steel rockers typically open up to about .005". As all of the parts mate and the lifter wheel compresses the cam lobe surface a tic you will need to readjust a time or two. After going through this on my 460 currently in the LTD I've not had to jack with it more than once a year.

You will need the appropriate hydraulic roller springs for the eddy heads. Eddy springs are too light imo for good control. 160 seat and about 420 to 440 open. Beehive springs also work VERY well and are very stable at higher rpm than your typical dual with damper.


S
 
#9 ·
I'm definatley no expert but you may want to check out distributor gear options with roller cams. You mentioned your car is a daily driver it's my understanding that the 385 series engine with roller lifters have to run either a bronze or composite distributor gear, neither of which will i think will last in daily driver applications. Like i said i'm not an authority and may be wrong just didn't want you to buy a roller setup that doesn't fit your application.
 
#10 ·
The gear required depends on the material the cam is made of. 3180 billet requires bronze or composite. Comps cams dash 8 cams can run a melonized steel gear.

Directing additional oil to the distributor gear via drilling the right lifter galley plug or doing paul kanes mod from the from cam bearing saddle to shoot oil at the gear are both helpful.



S
 
#14 ·
Overhead cams don't have to deal with the mass of the tappet plus pushrod - but who knows. I doubt there will be many engineers interested in developing any new HLA technology for our old engines.
 
#15 · (Edited)
Good points. More mass, acceleration, velocity means huge amount of pressure in that little tappet. Probably an explosive amount. Probably need more square inches to spread out the load. Call the physicists.

If people ever trusted them there would still be a very limited market.

Long way around the barn for that 30hp or so. Whatever it is.
 
#16 ·
I was thinking more of durability than HP gains. Flat tappet cams are fine but I worry about oil choices. Right now I am running Valvoline ZR1 and I know there are additives but with a roller cam I wouldn't have to worry about the additives. Plus the extra HP is a nice benefit
 
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