100# SEAT PRESSURE ON ROLLER CAM
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100# SEAT PRESSURE ON ROLLER CAM
I am curious as to how the cup engine builders are running 100# of seat pressure on a roller cam? I know part of the technology is using 7mm valve stems,light retainers,steel rockers,1/2" pushrods ,Jesel keyway lifters & high rate springs but there is bound to be a difference in the cam lobe profiles.I have heard of the controlled valve float principle but the setting of the valve back on the seat is what really mystifies me.
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Re: 100# SEAT PRESSURE ON ROLLER CAM
A lower seat force can be used if all valve train components are very light weight and the cam shaft acceleration profile is mild.perfconn wrote:I am curious as to how the cup engine builders are running 100# of seat pressure on a roller cam? I know part of the technology is using 7mm valve stems,light retainers,steel rockers,1/2" pushrods ,Jesel keyway lifters & high rate springs but there is bound to be a difference in the cam lobe profiles.I have heard of the controlled valve float principle but the setting of the valve back on the seat is what really mystifies me.
Re: 100# SEAT PRESSURE ON ROLLER CAM
Exactly and I'd say the super top Secret ramp profile is key plus the featherweight valvetrain Dave hit the nail on the head
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Re: 100# SEAT PRESSURE ON ROLLER CAM
What gives better high speed valvetrain control? A spring with a lower rate that is shimmed to give a high seat load or a spring with a higher rate that is shimmed less but has a higher resonant frequency and thus more resistant to spring surge in the operating range of the engine. Spring surge can cause a spring to have zero seat load at certain engine speeds so I'd put my money on a higher rate spring irregardless of the seat load.
Re: 100# SEAT PRESSURE ON ROLLER CAM
Remember, 100# with a 2.3:1 rocker ratio is 230# at the lifter.
Mike Jones
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Re: 100# SEAT PRESSURE ON ROLLER CAM
So called 'rev-kit', spring/s between the lifter & block besides the spring/s between the retainer & head?
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Also, smaller. it's spring isn't working at a mechanical disadvantage against the valve train's biggest mass.
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Also, smaller. it's spring isn't working at a mechanical disadvantage against the valve train's biggest mass.
Re: 100# SEAT PRESSURE ON ROLLER CAM
no rev-kitallencr267 wrote:So called 'rev-kit', spring/s between the lifter & block besides the spring/s between the retainer & head?
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Also, smaller. it's spring isn't working at a mechanical disadvantage against the valve train's biggest mass.
Mike Jones
Jones Cam Designs
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Jones Cam Designs
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Re: 100# SEAT PRESSURE ON ROLLER CAM
Rev kits went out in the 80's Most of the lifters made today won't even take a rev kit..9500 with no rev kit equals not needing a rev kit.
Re: 100# SEAT PRESSURE ON ROLLER CAM
2.3-1...wow that's a game changer. The lobe they are running must be pretty small then as far as lobe lift. I assume that is what allows them to do this, plus the lightweight valvetrain. That had been my point when talking about roller cams with some local people I race with. One builder goes by the 100lbs open per .100" of lift. That sort of makes sense to me, and I see his point but what makes a .600" lift roller different than a .600" flat tappet? The flat tappet spring is able to shut the same valve at 7000rpm why wouldn't it be able to shut a roller tappet?
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Re: 100# SEAT PRESSURE ON ROLLER CAM
Larger wheel diameter on the lifters too.
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Re: 100# SEAT PRESSURE ON ROLLER CAM
The first solid roller I ran was a used .550 lift with 2 different brands of lifters and I ran this spring...
"Upside down" Conical Valve Spring
Rate: 362 lbs
Inner Diameter: 1.070'' Top, .866'' Bottom
Outer Diameter: 1.454'' Top, 1.250'' Bottom
Seat Load: 100 lbs at 1.750''
Open Load: 281 lbs at 1.250''
Coil Bind Height: 1.135''
It would turn 7000 with out missing a beat, I guess it worked because I didn't know any better.
"Upside down" Conical Valve Spring
Rate: 362 lbs
Inner Diameter: 1.070'' Top, .866'' Bottom
Outer Diameter: 1.454'' Top, 1.250'' Bottom
Seat Load: 100 lbs at 1.750''
Open Load: 281 lbs at 1.250''
Coil Bind Height: 1.135''
It would turn 7000 with out missing a beat, I guess it worked because I didn't know any better.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Re: 100# SEAT PRESSURE ON ROLLER CAM
It worked because it was a mild .550" lift cam. If the lift curve is the same, the valve doesn't know if it's a roller cam, or a hydr flat tappet.GARY C wrote:The first solid roller I ran was a used .550 lift with 2 different brands of lifters and I ran this spring...
"Upside down" Conical Valve Spring
Rate: 362 lbs
Inner Diameter: 1.070'' Top, .866'' Bottom
Outer Diameter: 1.454'' Top, 1.250'' Bottom
Seat Load: 100 lbs at 1.750''
Open Load: 281 lbs at 1.250''
Coil Bind Height: 1.135''
It would turn 7000 with out missing a beat, I guess it worked because I didn't know any better.
Mike Jones
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Re: 100# SEAT PRESSURE ON ROLLER CAM
Yeah it was one of Comp's old "Street Solid Roller" I think it was something stupid like 255/555 if memory is correct...Long, Slow and not a street cam.CamKing wrote:It worked because it was a mild .550" lift cam. If the lift curve is the same, the valve doesn't know if it's a roller cam, or a hydr flat tappet.GARY C wrote:The first solid roller I ran was a used .550 lift with 2 different brands of lifters and I ran this spring...
"Upside down" Conical Valve Spring
Rate: 362 lbs
Inner Diameter: 1.070'' Top, .866'' Bottom
Outer Diameter: 1.454'' Top, 1.250'' Bottom
Seat Load: 100 lbs at 1.750''
Open Load: 281 lbs at 1.250''
Coil Bind Height: 1.135''
It would turn 7000 with out missing a beat, I guess it worked because I didn't know any better.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
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Re: 100# SEAT PRESSURE ON ROLLER CAM
camking,
i am going to guess,
low seat pressure,high spring rate to control the valve at high rpm,and valve loft but they probably like the valve lofting if it stays in control
low seat pressure to save the valve face and seat from getting beat to hell because of the 55 deg plus seats angle for 500 mile race
again i am usually wrong most of the time but happy to learn
steve c
i am going to guess,
low seat pressure,high spring rate to control the valve at high rpm,and valve loft but they probably like the valve lofting if it stays in control
low seat pressure to save the valve face and seat from getting beat to hell because of the 55 deg plus seats angle for 500 mile race
again i am usually wrong most of the time but happy to learn
steve c
steve c
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Re: 100# SEAT PRESSURE ON ROLLER CAM
how many remember the 1/4" X 1/4" steel bar that went into the lifter oil galley and fit thru a slot in the roller lifter to keep it from rotating ?? I remember using this in the 60s but I don't remember the brand