Budget Rocker choice

COMP Pro Magnums 1.6 or PRW stainless 1.6

  • Comp Pro Magnum

    Votes: 9 60.0%
  • PRW stainless 1.6

    Votes: 6 40.0%

  • Total voters
    15
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LMAO! YES!
The head itself is fine. Once you start playing with the Dimensions of the parts being used, you start running into issues. Another good example of the milled heads is that I had to mill my intake .070 on the intake to head surfaces. The bottom of the intake is very close to the blocks China wall.

This particular block is not milled but the heads were. An amount I have forgotten long ago. That is less than a 3/16 gap. Mill the block & heads enough, that will disappear and the intake will have to be milled more as well as the bottom of it.
image.jpg
 
LMAO! YES!
The head itself is fine. Once you start playing with the Dimensions of the parts being used, you start running into issues. Another good example of the milled heads is that I had to mill my intake .070 on the intake to head surfaces. The bottom of the intake is very close to the blocks China wall.

This particular block is not milled but the heads were. An amount I have forgotten long ago. That is less than a 3/16 gap. Mill the block & heads enough, that will disappear and the intake will have to be milled more as well as the bottom of it.
View attachment 1715492441
Holey gap Batman!
There are those details again.
 
The gap was much larger when I started that mess...
LMAO
 
Aftermarket roller rockers are seldom accurate on ratio except for T&D and Jessel stuff.

Use beehive springs and your clearance issues disappear.
 
How much is "tiny"? That's a relative term. It can't be measured. I can tell you that I've seen geometry that was in error well over 50%, and the average is about 30%. That is measureable, and hardly tiny.
Can we ask 30% or 50% of what parameter or indicator that we are measuring?

There is a point where what you get can be lived with in lower performance uses and cruisers, etc. There is always a cost-benefit to all of this.
 
Can we ask 30% or 50% of what parameter or indicator that we are measuring?

There is a point where what you get can be lived with in lower performance uses and cruisers, etc. There is always a cost-benefit to all of this.
Every engine is different and has different requirements, so there is no set parameter. Those numbers are from of the corrections I have done, based on where the geometry was, compared to where it should be. As the Trick Flow heads become more prevalent, that average number will go down because they have raised the stands, which requires less correction.

If everyone is so anxious to "just get by" without fixing this, why does anyone modify anything? After all, it would be "good enough" with a stock motor. Why mess it up with aftermarket parts? It's not a race engine, and you can lose just as easily with a stock motor, as with a modified motor that isn't done right. And, if it's all about the sound, you can get that with a lazy cam that uses mild spring pressures that won't kill the stock rockers.

I'll say it again, if it isn't worth setting up a roller rocker correctly, it isn't worth the roller rocker to begin with. You're better off leaving it stock. The cost vs benefit argument means you either can't afford roller rockers, or you aren't willing to spend the money to install them properly. The correction should be considered part of the rocker budget, just like boring and honing is part of the cost of installing oversize pistons.

In all seriousness, what other aspect of an engine build would guys readily accept even a 30% error? Balancing? An 1800 gram bobweight is now either 1200, or 2400 grams, depending on whether it is heavy or light. Bearing clearance? A targeted .0025" oil clearance is now .00175", or .00325", again depending on whether it is big, or small that percentage. Ring gap? A typical .020" gap would now be either .014", or .026". Oh, here's a good one. Guys are always stressing over net valve lift. Let's take a simple .500" lift. At 30%, you could be at .350" or .650". Some would love to see the .650", but imagine getting the .350" when most guys complain about losing .010". There would be a national day of mourning.

For everyone who says "it's not that bad", when it comes to rocker geometry, I challenge them to tell me exactly how bad it is. Not with relative terms, but with actual measured numbers. If you can't do that, then you can't truthfully say "it isn't that bad", because you don't know. I don't say that to come across as a jerk (I don't try to belittle anyone, ever), but to say that if everybody knew and understood this subject, they wouldn't put a motor together without making it right. I'm confident of that!

Forgive me for the lengthy post, and again, I'm not trying to talk down to anyone, and I hope it isn't taken that way. I'm just trying to help folks understand, using pure logic, why it's so important.
 
Aftermarket roller rockers are seldom accurate on ratio except for T&D and Jessel stuff.

Use beehive springs and your clearance issues disappear.
Agreed, and if using factory rockers, especially ductile irons, that is a good way to gain clearance.

With a roller rocker, you may gain clearance, but what other issues remain? My point, fix the main issue (geometry), and they all go away.
 
A simple question was asked: We still don't know 30 to 50% of WHAT parameter. Is this sweep pattern width? Reduction in loss of lift from theoretical maximum lift? Variation in some part of the valvetrain speed compared to theoretical optimum?

A percentage without it referenced to anything is meaningless. A number was thrown out trying to say something but no one knows what it is you are saying!
 
A simple question was asked: We still don't know 30 to 50% of WHAT parameter. Is this sweep pattern width? Reduction in loss of lift from theoretical maximum lift? Variation in some part of the valvetrain speed compared to theoretical optimum?

A percentage without it referenced to anything is meaningless. A number was thrown out trying to say something but no one knows what it is you are saying!
And, the question was answered. I said geometry, which is the shaft height for a given combination, which varies. But, if you need an example of what 30% is, here you go.

If the shaft needs to be .300" below the perpendicular plane, and it is .400" below, then it is .100" more than .300", so it is 30% in error (technically 33.333333~%).

Now, if the shaft should only be .250" below the perpendicular line, and it was .400" below, then it would be in error 40%. I've had shafts as much as .380" lower than they were supposed to be. How much error is that when the shaft is only supposed to be down .300"? How about 127%. Is that bad?
 
And, the question was answered. I said geometry, which is the shaft height for a given combination, which varies. But, if you need an example of what 30% is, here you go.

If the shaft needs to be .300" below the perpendicular plane, and it is .400" below, then it is .100" more than .300", so it is 30% in error (technically 33.333333~%).

Now, if the shaft should only be .250" below the perpendicular line, and it was .400" below, then it would be in error 40%. I've had shafts as much as .380" lower than they were supposed to be. How much error is that when the shaft is only supposed to be down .300"? How about 127%. Is that bad?

Quick question from a bonehead - Has any testing been done to actually quantify what that 30% results in, in term of lost duration/lift, hp (verified on a dyno), etc? At what point does valve train geometry that's not perfect actually become something that's noticeable in the real world?
 
Quick question from a bonehead - Has any testing been done to actually quantify what that 30% results in, in term of lost duration/lift, hp (verified on a dyno), etc? At what point does valve train geometry that's not perfect actually become something that's noticeable in the real world?


Broken parts. Needing more spring pressure for the same or less RPM. Rapid guide wear and the beating up of the valve job that follows.

Mike will have more Im sure.
 
Broken parts. Needing more spring pressure for the same or less RPM. Rapid guide wear and the beating up of the valve job that follows.

Mike will have more Im sure.

Tell that to everyone who's been running aftermarket rocker arms without any fancy geometry correction kits with zero problems. Sorry - not buying it! Actual empirical data would be useful for your argument. Anecdotal **** doesn't cut it. We need numbers.
 
Tell that to everyone who's been running aftermarket rocker arms without any fancy geometry correction kits with zero problems. Sorry - not buying it! Actual empirical data would be useful for your argument. Anecdotal **** doesn't cut it. We need numbers.


I didn’t give you anecdotal ****. I’ve been doing this **** since 1980 so ive lived it.

And then people like you, who claim your junk runs fine, who have never seen a dyno or had an engine on a dyno tell everyone that geometry correction is a waste of money. That is straight ignorant.

Mike just laid out the math. Even you should get that.

It used to be the only way to fix this junk was to mill the stands and use offset shafts and stands. It was expensive and most guys passed on it, with the results you don’t believe above.

Now, the way to fix it is very economical to correct it. But your no experience *** feels like you need to run into every thread and tell everyone how your **** runs fine with junk geometry.

Some day, when you discover how ignorant that is, you will correct your geometry.
 
Some day, when you discover how ignorant that is, you will correct your geometry.

I actually plan on getting one of his kits for the big block I'm building. But unlike the majority of folks, I am looking for every last hp I can for that particular build, and it's not a 'budget build.' I just wish there was actual test data available showing what real world difference a 30% difference (or any % difference) makes. In other words , at what point is there a real-world measurable difference in lift or power. Is it just valve train/guide life? Ok - how much??? Again - give us numbers. I'd bet Mike has those answers - I would hope so anyway.

Not sure why you pipe up if you don't have an answer to a question that specific. Maybe you two oughta get a room.
 
Quick question from a bonehead - Has any testing been done to actually quantify what that 30% results in, in term of lost duration/lift, hp (verified on a dyno), etc? At what point does valve train geometry that's not perfect actually become something that's noticeable in the real world?
30% is actually a little bit of a lowball number. With exception for the Trick Flow heads, the average is probably closer to 40-50 percent.

I have done dyno testing on a small block combo that had a 52% error. It went into severe early valve float, and limited rpm well below the intended shift rpm. After correction, the rpms were clean thru the shift rpm and beyond. We gained another 800 stable rpm, and picked up another 46 horsepower at the shift point. The conventional wisdom would have been to throw more spring on the heads to control the float, but it wasn't necessary. Valve side loading was reduced, which helped save the guides over the long haul. And, the jackhammering effect of being in valve float would have destroyed parts in short order. Oh, and this was a mild hydraulic cammed 9 to 1 CR 360.

While we didn't break anything on that engine, I've seen enough broken rockers, dropped valves, tore up guides etc, to know how critical this is.

Lastly, you're not a bonehead. A bonehead refuses to think or learn anything new.
 
I actually plan on getting one of his kits for the big block I'm building. But unlike the majority of folks, I am looking for every last hp I can for that particular build, and it's not a 'budget build.' I just wish there was actual test data available showing what real world difference a 30% difference (or any % difference) makes. In other words , at what point is there a real-world measurable difference in lift or power. Is it just valve train/guide life? Ok - how much??? Again - give us numbers. I'd bet Mike has those answers - I would hope so anyway.

Not sure why you pipe up if you don't have an answer to a question that specific. Maybe you two oughta get a room.


Did you miss the part where I said mike would have more to say? It’s his deal so I why not let him post the data? You wouldnt have believed me had I said it. I’ve seen engines pick up 600 useable RPM with just a geometry correction. No more spring load. That says a bunch right there. And, funny enough the power went up with the extra RPM, just like it should have.
 
And, the question was answered. I said geometry, which is the shaft height for a given combination, which varies. But, if you need an example of what 30% is, here you go.

If the shaft needs to be .300" below the perpendicular plane, and it is .400" below, then it is .100" more than .300", so it is 30% in error (technically 33.333333~%).

Now, if the shaft should only be .250" below the perpendicular line, and it was .400" below, then it would be in error 40%. I've had shafts as much as .380" lower than they were supposed to be. How much error is that when the shaft is only supposed to be down .300"? How about 127%. Is that bad?
If you don't mind, I have a question for you. You may or may not have an answer that I can comprehend but here's my set up. Block was checked for square and the j heads were shaved to 62 cc to get 10.2 comp. Pocket ported and 2.02s installed. Intake was cut to align ports etc. The machinist is a well known old salt that built race motors for years. I stuck the racer brown ssh 44 .510 lift 108cl 292 dur. hydraulic cam in it with johnson lifters. Comp pro 1.5 rollers. So I didn't have to shim much left or right to center them on the tips as they aligned well. Kept the adjuster 1-2 threads showing under and got pushrods to fit. Installed them .015 preload and blackened the valve tips. Was towards the exhaust slightly. Installed .010 shims under the shafts and then they rolled at center after a few revolutions. The mark of the roller was spot on and about .025 was the thickness of the line that the roller left. It was no where near traveling from the intake to exhaust side. Centered and about .025 roll on the tip. This may not be corrected by the way you explained so what would be my goal to correct geometry? I imagine a large solid cam would be way worse but I don't actually think this part has to do with the correct geometry but I am going to build more like it and the knowledge is appreciated.
 
I actually plan on getting one of his kits for the big block I'm building. But unlike the majority of folks, I am looking for every last hp I can for that particular build, and it's not a 'budget build.' I just wish there was actual test data available showing what real world difference a 30% difference (or any % difference) makes. In other words , at what point is there a real-world measurable difference in lift or power. Is it just valve train/guide life? Ok - how much??? Again - give us numbers. I'd bet Mike has those answers - I would hope so anyway.

Not sure why you pipe up if you don't have an answer to a question that specific. Maybe you two oughta get a room.
Get a room? Was that really necessary?
 
Tell that to everyone who's been running aftermarket rocker arms without any fancy geometry correction kits with zero problems. Sorry - not buying it! Actual empirical data would be useful for your argument. Anecdotal **** doesn't cut it. We need numbers.
The best I can offer is a fellow FABO member near me used a kit from B3 and his 1/4 mile ET dropped by a tenth and change. He told me it was worth my time to contact him for the kit.
 
NM mentioned low performance and cruisers above
I do not see where roller tip rockers are justified for these builds.
I think of the jackrabit oill pumper curved arm that keeps the cable straight and right above the hole when it goes up and down
move it up or down from where it was installed it would not work
I posted a quote from a well respected head guy/ engine builder who said that anywhere the stripe is on top of the valve (not running off the edge obviously) is ok
but if the stripe gets wide then guides are gone real quick
I think it was Chris Straub but could have been someone else
anyway back to the oil well analogy
Think not of the rocker and the valve tip but look at the motion from the side
like an arm coming from the center of the shaft with an ARC on the end - the arc is the length of the shaft to the middle of the roller of foot
now sit the end of your valve touching the arc and rotate that point on the arc
see what a difference it makes if the touching point is in the center of the arc
or if the fulcrum is high as in Crane's "quick lift" method
or low the way a lot of builds come out with no correction
two high u get overarcing with the rocker pointed way down
the other you get "underarcing"
You get underarcing with long valves or roller tip rockers,
What YR said
"Broken parts. Needing more spring pressure for the same or less RPM. Rapid guide wear and the beating up of the valve job that follows."
WHY?"
because you get the most rocker ratio when the (arm and roller) are at the point perpendicular to the valve stem
back to the ARC not hard to see when the rocker is up the arc or down the arc you have less valve motion per degree of rotation
or pushrod lift on the arc on the pushrod side- double trouble
NOw if we have that maximum multiplication nearer to maximum valve lift what is the cam trying to do
That's right
slow down the velocity to 0 when the lifter is going over the nose- and the rocker is fighting this deceleration
which is why you need the stronger springs, float the valves earlier, float the valves
and floating the valves brakes parts
As does closing to quick and getting valve bounce- that's where too low a piviot helps a too quick cam design like the Comp HL series by ODHarold
Harold learned and that's one reason the Lunati versions are a better compromise- Ultradyne somewhere in between.
Harold had enough computer power to be able to have many more polydines and many more paramaters in his later designs
You can look at the problem graphically as I suggest with my "MIDARC" or do the math
 
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