1.7 rocker effect

[Raleigh111]

   just curious here...but why did S&S design their new T143 crate engine and use 1.725 rockers arms in that engine?
It seems if the 1.725's didn't help...they would have ran the stock ratio arms.

Ray
i do not know the answer to what i am about to say so dont take this the wrong way, asking not stating or telling.

a while back i had a conversation with a guy that makes cams for a living and he said dont bother with those high ratio rocker arms it will rob you of horsepower as it takes more force to lift them. if you want higher lift buy a different cam, gave me some example of a tidder todder at a park? still trying to figure that out in my head. car guys use them all the time and have been for many many years.

i used them anyways and it helped me in my situation?

i thought that exact same thing when i saw they were using them!! if they rob horsepower why not have rocker arms with even lower ratio ? geometry ?

[pwmorris]

Here is some notes from Jim Hand, a Pontiac car guy, but the testing results were similar to mine.
Harley street motors with very moderate lift and compression don't exactly tax a valve train, but I have seen Jesel rockers in a VTwin with a 1.9 intake rocker ratio, so used wisely in the right motor combo, adding lift in either the intake or both rockers can see benifits-Including my current 126" street bike motor running 1.7's on just the intake (didn't test using both int and ex, as I was happy with the results as is, but maybe in the future).

JH-
" If the 1.5 arms are replaced by 1.65. Is this good? On any engine that can use the extended duration, it is very good. A 455 with the 068 will feel much stronger in the normal driving range and will pick up as much as .2 seconds in the 1/2 with this change. However, if the cam duration is already adequate with 1.5 ratio arms, the added duration caused by 1.65 arms may result in a loss of performance. We recently witnessed a 455 street car that runs in the 12.70 range with a 041 cam lose performance and driveability when the stock 1.5 rockers were replaced with a set of 1.65 Harland Sharp units. The 041 cam/1.5 rocker combination exactly matched the overall setup of this vehicle, and the increased cam timing unbalanced the combination.

A change in rocker arm ratio can provide a significant boost in usable power, or they can actually cause a loss, depending on what duration and lift the engine needs and what it has before the change. Note that push rod length and stiffness, and lifter leakage, can affect actual valve lift, but these factors will remain relatively constant. The real concern is not theoretical numbers, but how your engine responds to the overall combination."

[Raleigh111]

Here is some notes from Jim Hand, a Pontiac car guy, but the testing results were similar to mine.
Harley street motors with very moderate lift and compression don't exactly tax a valve train, but I have seen Jesel rockers in a VTwin with a 1.9 intake rocker ratio, so used wisely in the right motor combo, adding lift in either the intake or both rockers can see benifits-Including my current 126" street bike motor running 1.7's on just the intake (didn't test using both int and ex, as I was happy with the results as is, but maybe in the future).

JH-
" If the 1.5 arms are replaced by 1.65. Is this good? On any engine that can use the extended duration, it is very good. A 455 with the 068 will feel much stronger in the normal driving range and will pick up as much as .2 seconds in the 1/2 with this change. However, if the cam duration is already adequate with 1.5 ratio arms, the added duration caused by 1.65 arms may result in a loss of performance. We recently witnessed a 455 street car that runs in the 12.70 range with a 041 cam lose performance and driveability when the stock 1.5 rockers were replaced with a set of 1.65 Harland Sharp units. The 041 cam/1.5 rocker combination exactly matched the overall setup of this vehicle, and the increased cam timing unbalanced the combination.

A change in rocker arm ratio can provide a significant boost in usable power, or they can actually cause a loss, depending on what duration and lift the engine needs and what it has before the change. Note that push rod length and stiffness, and lifter leakage, can affect actual valve lift, but these factors will remain relatively constant. The real concern is not theoretical numbers, but how your engine responds to the overall combination."

good info thanks! Makes sense you use them to fine tune if the cam is one way or another? any mention of it taking more force to lift the higher ratio arm?

[1FSTRK]

You take the valve spring pressure and multiply it time the rocker ratio to get the pressure on the lifter.

The smart guys will account for this when picking cams and setting up springs for the ratio of the rocker.

[Admiral Akbar]

107 ci set at 10.8 (est) ccp 205 (est)
massaged on MVA'S
massaged on SE 58MM T/B---5.3 inj
TMAN 590 CAM
RUSH WRATH 2.50

With this build I would almost best that what Paul (pwmorris) says rings true... No gain maybe some loss..

[1FSTRK]

There have been several that have already posted that experience and testing is the only real way to tell for sure.

Here a good example of "you do not know unless you test".



Care to guess which run is a 590 lift 246 duration cam with stock ratio rockers and which is the .511 lift 242 duration cam with 1.725 ratio rockers. Both were fully tuned.

[Matt C]

Blue line - stock rockers

[1FSTRK]

Blue line - stock rockers

Buzzzzzzzzzzzz

Want to try the bonus round where the prizes are double?


ADDED
MCE, Not trying to be a knob, my attempt at humor, don't take it as a personal jab.

Here is a 105ci Woods 9F with Stock ratio rollers and with 1.7 ratio rollers.
It required bigger thunder jets and less timing.
They do not always work out like this but the test is the only way I have seen anyone know for sure.

[Matt C]

I'm ok with it 

Sometimes it works, sometimes it doesn't. Only one way to know. Right?

[jam65]

If you need to use high ratio rockers, you have the wrong cam.

So what is your position on this subject?

[Matt C]

If you need to use high ratio rockers, you have the wrong cam.

So what is your position on this subject?

I feel these are more of a fine tuning or an R&D tool, (to see if the motor wants more
cam).

I'm not a fan of using them as a permanent solution. Although that certainly has been
done by others. jmo tho

[PanHeadRed]

I'm considering adding a set of 1.7 rockers to my build, intake only,its a tman 590 cam, how does the additional lift figure in.

I'd put them in on both sides, assuming parts won't collide. If only one side I'd consider the EX side as strongly as the IN side as valve movement will speed up and that in it's self is a benefit. But as others have stated sitting on the bench they only offer potential, added to the engine is the only way to determine if your application will realize the potential.

Any part that opens the valves higher and/or faster has the potential to add power.

[Durwood]

If you need to use high ratio rockers, you have the wrong cam.

So what is your position on this subject?

I feel these are more of a fine tuning or an R&D tool, (to see if the motor wants more
cam).

I'm not a fan of using them as a permanent solution. Although that certainly has been
done by others. jmo tho

I agree, I did see some performance gains with them in my 103' with 204's, so I went to AP-57's.

I have seen two different builds with these ran long term, 15k and 25k, that an exhaust lifter took a dump, it actually took the roller needles out.

I can't say for sure that it was the 1.725 rockers that caused the failure but both builds had good quality tappets.

After some research I feel the leverage increase may very well have been the culprit.

Daren

[1FSTRK]

Lets look at the math rather than the myth.

First look at an example of close to stock numbers
Ratio    lifter seat    lifter open  spring seat   spring open
1.625   219.4 lbs   650.0 lbs   135.0 lbs        400.0 lbs

Now with the 1.725
1.725   232.9 lbs   690.0 lbs   135.0 lbs        400.0 lbs

And the increase pressure at the lifter with 1.725 ratio
Increase     13.5 lbs     40.0 lbs

Now say you buy some fancy high performance springs for your stock ratio rockers
Ratio    lifter seat    lifter open  spring seat   spring open
1.625   260.0 lbs   780.0 lbs   160.0 lbs   480.0 lbs

As you can see the spring kits far exceed the the lifter pressure of simply adding the bigger ratio rockers.

Now there are things to consider when using higher ratio rockers with performance springs when you set the spring pressure but any good cylinder head specialist will know this and take care of this when setting things up for you.

Some of the things to consider are the weight of the lifter and pushrod are not accelerated as quickly and do not move as far with the smaller cam and the higher ratio rocker for the same valve travel. Also because the valve spring not only closes the valve but also pushes the pushrod and lifter back down it's job is easier because it now has more leverage over the pushrod and lifter so less spring pressure would be needed to move the same weight. There is a lot more to it but simply put running a stage two cam with higher ratio rockers will not over load your lifters or hurt your longevity unless you really screw up something else in your set up.

[sfmichael]

good stuff 

[Durwood]

As I stated Eric, I am not sure exactly what caused these failures, but they were both hot rods, and both lost the rear exhaust lifter.

The set of SE 1.725 I took off of my bike with about 5k on them both of the exhaust rocker tips had some abnormal wear, one much worse than the other and it's not lube related as I use top shelf oil and change it often.

Could be a myth, but I wont ever run them on the exhaust side again. JMO

[sfmichael]

As I stated Eric, I am not sure exactly what caused these failures, but they were both hot rods, and both lost the rear exhaust lifter.

The set of SE 1.725 I took off of my bike with about 5k on them both of the exhaust rocker tips had some abnormal wear, one much worse than the other and it's not lube related as I use top shelf oil and change it often.

Could be a myth, but I wont ever run them on the exhaust side again. JMO

interesting

[1FSTRK]

As I stated Eric, I am not sure exactly what caused these failures, but they were both hot rods, and both lost the rear exhaust lifter.

The set of SE 1.725 I took off of my bike with about 5k on them both of the exhaust rocker tips had some abnormal wear, one much worse than the other and it's not lube related as I use top shelf oil and change it often.

Could be a myth, but I wont ever run them on the exhaust side again. JMO

What brand of rocker?
If they all had the same bigger ratio, why would one wear more than the others if the wear was caused by the new ratio?
I do not dispute the problems you had/found, I only question that you blame it on a ratio change.

[Durwood]

As I stated Eric, I am not sure exactly what caused these failures, but they were both hot rods, and both lost the rear exhaust lifter.

The set of SE 1.725 I took off of my bike with about 5k on them both of the exhaust rocker tips had some abnormal wear, one much worse than the other and it's not lube related as I use top shelf oil and change it often.

Could be a myth, but I wont ever run them on the exhaust side again. JMO

What brand of rocker?
If they all had the same bigger ratio, why would one wear more than the others if the wear was caused by the new ratio?
I do not dispute the problems you had/found, I only question that you blame it on a ratio change.

They were new SE non roller rockers. Only running them 5k I removed them when I changed my cams and noticed the wear only on the exhaust rocker tips, one is junk, and the valve tips were fine.
If you remember, I know Stroker does, I contemplated using them on the 57's before I pulled it down.

I reinstalled my stock rockers with the 57's and have had it apart 2 times in the last 16k miles for other reasons, once just a month ago and the stock rockers still look great.

Why ratio? It was a culmination of seeing the failed exhaust lifters, both had 1.7 roller tip rockers, and the abnormal exhaust rocker arm tip wear on mine, I decided not to try them again, at least not on the exhaust side.

Could be a huge coincidence, but one that I will be able to rule out of the equation moving forward.

Daren

[1FSTRK]

Your rockers, one worse than the other sounds like poor quality control at production. If both valve stems were fine than the rockers could have been too soft.

The lifter bikes there is just not enough information to make any type of call what the cause was. For me to come to your conclusion, all bikes with 1.7 on the exhaust would have to ruin both exhaust lifters and they do not. I also have seen many, if not most lifters fail when running stock ratio rockers.

I do not mean to challenge you, I just feel like when things come up and we simply blame a part and move on nothing is solved or learned. Thanks for sharing your experiences with the 1.7's, wish for you it had been better.


Added
Another thing to note on your bike is the valve arm end of the SE 1.7 rocker is identical to the stock one, it is the pushrod cup they move so the contact point and movement on the valve when opening is identical to a stock rocker with a higher lift cam. Just no way the failure was due to the ratio. 

[Don D]

Consider factoring if the valves turn or remain stationary

[Durwood]

Your rockers, one worse than the other sounds like poor quality control at production. If both valve stems were fine than the rockers could have been too soft.

The lifter bikes there is just not enough information to make any type of call what the cause was. For me to come to your conclusion, all bikes with 1.7 on the exhaust would have to ruin both exhaust lifters and they do not. I also have seen many, if not most lifters fail when running stock ratio rockers.

I do not mean to challenge you, I just feel like when things come up and we simply blame a part and move on nothing is solved or learned. Thanks for sharing your experiances with the 1.7's, wish for you it had been better.

Challenge is good. I too wondered about QC but it's funny that the 2 intake rockers were perfect, only the exhaust rockers were affected, rear more than front, maybe someone running them now could take a look to see how theirs are doing.

And the lifter failure was also the rear and could be the front was to follow? who knows as all 4 were changed.

I didn't spend the time to investigate further considering the fact that the higher ratio rockers seem to only help performance on the intake side and have read cases where when used on the exhaust side can actually make the power go backwards.

I still have those rockers and will be more than happy to snap some pics and post them when I am in the shop next week.

[1FSTRK]

It is curious about the intake both being fine. I was thinking about the geometry difference with the exhaust valve being at a different angle than the intake but none of that changes from stock rocker to the SE rocker so that is out. I could see if your bike eat the ball off the pushrod, that contact point is where the change takes place but the pressure and geometry at the valve stays exactly the same with the exception of the extra travel which it the same as adding some cam lift. Just does not makes sense.

One thought, inspect the SE rockers for the angle of the valve oiling hole and the size as well as condition compared to a stock rocker. Maybe a difference there or something not made right.

[kd]

Another consideration may be the difference in exh / int valve tip temp. A good quality oil should handle the difference though.

[1FSTRK]

Another consideration may be the difference in exh / int valve tip temp. A good quality oil should handle the difference though.

Yes that was why I was questioning the oil supply holes. It would not seem that the rocker pad on the stock would be able to handle any higher temp than the rocker pad on the SE.