roller rockers=power

[HSD]

anyone ever do a before and after dyno run after they installed roller rockers? wondering how much they really help

 

[BushogPapa]

Roller Rockers will add a small amount to your power...BUT, if your engine has the original cam in it, it probably should change to a cam with some real timing increases..
Many old tractors had NO over-lap at TDC and Roller Rockers will not change that..
You've got to Bake the Cake, before you Ice it..
The Roller Rockers should be like the Icing..!

Ron..

 

[Anonymous-0]

Roller rockers have bearings...stock rockers have bushings. Generally speaking, bearings have lower friction than bushings, and therefore require less horsepower to operate. Therefore, they don't CREATE horsepower; they just limit the parasitic loss through friction, and only to a degree.

NOW...is the difference substantial? Probably not. But when trying to get the maximum horsepower from an engine, they probably help. Obviously, for a stock overhaul, they're probably not gonna be worth the money. But if you're building some big HP, the change might be worth it.

 

[Anonymous-0]

Roller rockers have bearings...stock rockers have bushings. Generally speaking, bearings have lower friction than bushings, and therefore require less horsepower to operate. Therefore, they don't CREATE horsepower; they just limit the parasitic loss through friction, and only to a degree.

NOW...is the difference substantial? Probably not. But when trying to get the maximum horsepower from an engine, they probably help. Obviously, for a stock overhaul, they're probably not gonna be worth the money. But if you're building some big HP, the change might be worth it.

 

[HSD]

i was thinking the high ratio roller rockers

 

[gtx1967jewison]

The roller contributes more to longevity than power, HOWEVER its the high ratio that makes the difference. It is the nearest thing to getting the very fast lift rates that a ROLLER cam allows. the duration will NOT change, therefore not affecting idle quality. However the valve will open farther & faster. we dyno'd a stock late B jd before/after, on the belt, & it gained 3.5hp @ rated rpm of 1250. The gains would be more with higher compression, larger bore, head work etc. or a higher-lift cam. these were 2.0 ratio v.s. the 1.5 or 1.7 (cant remember) of the stock ones. Considering that the B only has around 26hp to begin with, as a percentage, this is a large gain. 10% would be only 2.6 hp, this is around 15% increase. Its a very fast, easy install in most cases. Be sure to keep in mind the possibility of valve/piston contact on some engines.

 

[Anonymous-0]

if increasing rocker ratio speeds up valve opening which it does .Then it most definately changes duration . Larger diameter mushroom lifters do this to. I cant seam to teach some anything.

 

[gtx1967jewison]

WOW! Please explain how the cam having not changed at all, can possibly act on the rockers (and therefore the valve) any sooner or later than before?! If the lash is set the same its not possible ! The valve begins opening at the same point in the cams (engines) rotation & finishes closing at the same point. THIS is duration. It is NOT open any longer. It merely opens faster once it begins to open, opens further, & closes faster. duration @ 0.050" is NOT changed. The valve stays at & near max lift longer but this is NOT an increase in duration. Its just a different curve.

 

[Anonymous-0]

when you increase the rocker ratio it affectively speeds up valve movement. This means the valve will reach opening height sooner than it would with a smaller rocker ratio. Since the increase in rocker ratio is seen on both sides of the cam lobe the overall valve timing lengthens (duration). Its about useless trying but it humors me.

 

[gtx1967jewison]

You are adding to the AREA under the curve, if viewed on paper, that the valve is open but NOT the duration. Duration is measured in degrees of rotation, which typically is counted from the time the valve has been opened 0.050" until it closes to the point of being 0.050" off the seat. A higher ratio rocker does NOT change this. therefore duration is not changed.

//when you increase the rocker ratio it affectively speeds up valve movement. This means the valve will reach opening height sooner than it would with a smaller rocker ratio.//

This statement is correct however the duration is measured in degrees of rotation which is the SAME. The valve still begins opening at exactly the same point in engine rotation & finishes closing at exactly the same point in engine rotation.

 

[Anonymous-0]

well they say three times the charm so 3rd try.
Duration is the angle in crank degrees that the valve stays off its seat during the cam rotation through the lobe lift.

 

[Anonymous-0]

...and how does the different rocker arms affect this????

 

[Indiana Ken]

(quoted from post at 16:50:30 01/20/12) WOW! Please explain how the cam having not changed at all, can possibly act on the rockers (and therefore the valve) any sooner or later than before?! If the lash is set the same its not possible ! The valve begins opening at the same point in the cams (engines) rotation & finishes closing at the same point. THIS is duration. It is NOT open any longer. It merely opens faster once it begins to open, opens further, & closes faster. duration @ 0.050" is NOT changed. The valve stays at & near max lift longer but this is NOT an increase in duration. Its just a different curve.

The cam determines duration however one has to define how it is measured. Typically the duration is measured at a specfic lift point, in this case we are talking about .050" as measured at the valve. Lets assume valve lash is set at zero; case 1) with a 1.5 ratio rocker the valve lift will be .050" at .033" cam rise, case 2) with a 2.0 ratio rocker the valve lift will be .050" at .025" cam rise. Since you are checking the duration at different starting/ending points on the cam the measurement will indicate that the duration has increased.

Another method is to check cam duration by measuring the lift at the lifter. This takes out the effect of the rocker arm.

 

[Anonymous-0]

(quoted from post at 17:51:40 01/20/12) ...and how does the different rocker arms affect this????

e would be running to be elected sooner and voting later

 

[gtx1967jewison]

they dont. just like i said. when your wrong your wrong. I mean no offense & enjoy all posts, one can learn from nearly all of them. but evidently he cant admit being wrong, idk. I myself am often wrong or misunderstand & then i appreciate other answers.

 

[gtx1967jewison]

correct. but for all PRACTICAL purposes, the miniscule amount of
valve duration at 0.050" is irrelevant. If you measure it at 0.005"
which is also sometimes done, the difference is almost nothing. &
as you stated, measuring it at the lifter, its identical, BECAUSE as i
stated the high ratio rockers do not change duration.

 

[Anonymous-0]

(quoted from post at 18:14:25 01/20/12) correct. but for all PRACTICAL purposes, the miniscule amount of
valve duration at 0.050" is irrelevant. If you measure it at 0.005"
which is also sometimes done, the difference is almost nothing. &
as you stated, measuring it at the lifter, its identical, BECAUSE as i
stated the high ratio rockers do not change duration.

Miniscule amount of valve duration at .050 is irrelevant. All this time I thought being able to fill a cylinder as soon as possible was what performance was about.

 

[north puller]

Ken nailed it.

If you measure duration seat to seat, or 1 deg lift to 1 deg lift, there is no change.

If you measure duration fron degrees of lobe lift, then there is no change.

However, if you measure duration at 0.050" of valve lift, then changing the rocker arm ratio will change the point in crank degrees at which the valve reaches this set point of lift. High ratio rockers reach 0.050" of valve lift sooner, and fall below 0.050" of valve lift later, and therefore have created more duration at the valve. Not a lot, but a few degrees.

A bonus to roller rockers is that the rocker tip "rolls" across the valve smother and creates less side force on the valve and prevents premature valve guide wear.

 

[johndeereman]

Wow a lot of mumbo jumbo to explain a basic system I think you guys are confusing yourselves. I believe the question is about ratio roller rockers like what Murphy"s sell. Yes they work basically all they do is change where the pivot point is so the valve is open further therefore keeping it open longer. Go back to basics guys it"s a simple lever.

 

[Dick W.]

I just wonder if you have 1 to 1 rockers the push rod would move the same distance as the valve. With a 2 to 1 rocker the valve would move twice as far as the push rod. Would the valve not start to open just a little sooner on the start of the cam lobe?
The push rod would only need to lift half as much as the lash with 2 to 1 rocker while the push rod would need to lift the same as the lash on a 1 to 1 rocker. Never tried any of this on an engine with a timing wheel attached.

 

[Anonymous-0]

(quoted from post at 19:09:04 01/20/12) I just wonder if you have 1 to 1 rockers the push rod would move the same distance as the valve. With a 2 to 1 rocker the valve would move twice as far as the push rod. Would the valve not start to open just a little sooner on the start of the cam lobe?
The push rod would only need to lift half as much as the lash with 2 to 1 rocker while the push rod would need to lift the same as the lash on a 1 to 1 rocker. Never tried any of this on an engine with a timing wheel attached.

AT .050 Increasing rocker ratio from 1.5 to 1.6 is normally 3 degree increase in duration at .050 .it changes some at different lobe lifts if measured. Comp cams seams to think that a 7 to 8 percent increase from a rocker increase in valve lift is worth 1 to 2 degrees increased duration at 50

 

[RandyB(MI)]

GTX , below , has the correct answer/analogy. Your question ,as it is stated, insinuates that the ONLY change would be the roller vs non roller. NOTHING said about ratio. So the simple answer is NO. One doesn't need a dyno to prove it. The roller provides longevity and stability , the ratio provides HP / torque. The only place where additional side load/friction would cause any measurable parasitic power loss might be a racing engine with 4 valves per cyl and 8 or more cylinders.Even then , they do it for longevity , not as a power adder. Not knocking anyones answers , but re-read the exact question as he worded it.

 

[Anonymous-0]

(quoted from post at 20:55:47 01/20/12) GTX , below , has the correct answer/analogy. Your question ,as it is stated, insinuates that the ONLY change would be the roller vs non roller. NOTHING said about ratio. So the simple answer is NO. One doesn't need a dyno to prove it. The roller provides longevity and stability , the ratio provides HP / torque. The only place where additional side load/friction would cause any measurable parasitic power loss might be a racing engine with 4 valves per cyl and 8 or more cylinders.Even then , they do it for longevity , not as a power adder. Not knocking anyones answers , but re-read the exact question as he worded it.

The only place gtx went wrong was quote the duration does not change with a higher ratio change. murphys roker are 1,85 usually and replace a 1.48 at least that i am familar with which is a 6 degree increase that can be measured with a degree wheel and dial indicator set up on spring retainer. just saying[i:88100459c4][/i:88100459c4]

 

[DAVE CHASE]

JUST TO ADD A COMMENT, HAD JOSH BLACKBORN CUT AND REWELD MY STOCK JD 50 ROCKERS AND TRACTOR WENT ON THE DYNO FROM 29.5 HP TO A FULL 34 HP. ONLY PULL DEAD WT WITH NEW UNCUT 14.9 ON 14" RIMS AND NOW WHEN I START TO SPIN OUT CAN THROTTLE BACK AND PICK IT RIGHT BACK UP. IN MY CASE WELL WORTH TO DO.DWC

 

[RandyB(MI)]

That's good , and so is Josh at what he does but still doesn't address the "roller" vs not question.

 

[MandM56082]

I have a Farmall Super M that i put murphys roller rockers on i had dyno numbers before the rockers and have since dynoed and i gained about 10 to 15hp and i couldn't tell you the amount of torque i gain it was enough to notice.

 

[RandyB(MI)]

But were they the same ratio as the stock ones you replaced? I doubt it very much. Therefore it still doesn't answer the original question , which was roller vs non roller tip with no other changes. Hate to beat this to death but the question was very simple and everyone seems to want to overthink it. Leave the "ratio" out of it. He didn't ask that.

 

[Anonymous-0]

Roller tips give minimal gains over solid tips. At lower spring pressures the gain is way less.

As for increased rocker ratio let me put it this way...
1.5 x 0 is the same as 1.95 x 0. If the cam is not calling for lift then the valve will not move.

If you are going by .05 lift numbers then of course duration etc will change by a few degrees. Otherwise, like said before it is the area under the curve that increases therefore breath to the engine increases. Definitely a good thing.

 

[Anonymous-0]

Actually its at any degree of lifter rise you choose to measure from that a as comp cams states a 7 to 8 percent valve lift increase. Increases the duration by 1 to2 degrees.

 

[Anonymous-0]

You should stop quoting and start thinking. Please reread what I said. This time I will put it in simpler terms. If the lifter ain't movin the valve ain't movin either. No matter what the rocker ratio....

 

[Anonymous-0]

(quoted from post at 00:06:21 01/25/12) You should stop quoting and start thinking. Please reread what I said. This time I will put it in simpler terms. If the lifter ain't movin the valve ain't movin either. No matter what the rocker ratio....

eah I got it the first time but was wondering which cam manufacturer has a formula to use for a lifter on the heal of the cam. most I have seen do it from some known amount of lifter rise.