TexasRoadRunner68
Well-Known Member
When do you generally start needing steel? High lift solid roller cams?
The tech at isky said 1.6 all the way, since it’s hard getting lift on a 1.5 ratio.
If you had one set of roller rockers, would it be 1.5 or 1.6?
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The tech at isky said 1.6 all the way, since it’s hard getting lift on a 1.5 ratio.
Past 800 lbs steel is a must..700 lbs is a good idea to run steel as the aluminum ones start to show some weakness. Depends on other factors as well.... A hydraulic roller will have a slow ramp compared to a racing solid roller.
I believe?? harlan sharp are rated 850 or maybe 800 lbs??? .9 lift( as the mopar one are from there heavy duty series). Mancini rockers are also made by harlan sharp and use the same rating.
When it comes to aluminum if you are pushing their max rating the aluminum will fail eventually. There is no duty cycle like steel. Steel for a certain load you can design how many cycles it will do before it gives up. Aluminum the only thing you can do is over build it for the application. I would say a rocker rated for 800lb+ is over built in a 415 application. Should last a long, long time.
I believe?? harlan sharp are rated 850 or maybe 800 lbs??? .9 lift( as the mopar one are from there heavy duty series). Mancini rockers are also made by harlan sharp and use the same rating.
When it comes to aluminum if you are pushing their max rating the aluminum will fail eventually. There is no duty cycle like steel. Steel for a certain load you can design how many cycles it will do before it gives up. Aluminum the only thing you can do is over build it for the application. I would say a rocker rated for 800lb+ is over built in a 415 application. Should last a long, long time.
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Why not just get a bigger lift cam and use the 1.5s to minimize the pressure created from the leverage, instead of using a smaller cam lift and the 1.6s with more leverage pressure, to compensate for the smaller cam? More lift and less pressure.
TexasRoadRunner68
Well-Known Member
I think the 1.6 gives you room on the more extreme end in the future. If Isky Racing Cams recommended that, there must be a sound reason. I’m thinking I’ll keep the 1.6 and just have the room to go more radical in the future.
70ChargerRT
Well-Known Member
Are we talking steel shaft and aluminum rockers?
451Mopar
Well-Known Member
On the Edelbrock Victor heads, I have the 1.6:1 ratio T&D Aluminum rockers and #275 seat pressure, about #750 Open spring pressure. At that point the rocker shaft and 5 hold downs studs are more an issue than the rocker arms.
On the split intake/exhaust rocker ratios, the intake is opening with about zero pressure in the cylinder (intake valve diameter / area * cylinder pressure) added to the spring seat pressure. The exhaust is opening the valve with much higher cylinder pressure, so the valve train will think the seat pressure is much higher.
Also, you might want the exhaust to open and close at a slower rate and max lift is not as big a concern because the exhaust cylinder pressures are way higher than the 1 atmosphere trying to fill the cylinder on the intake stroke.
On the split intake/exhaust rocker ratios, the intake is opening with about zero pressure in the cylinder (intake valve diameter / area * cylinder pressure) added to the spring seat pressure. The exhaust is opening the valve with much higher cylinder pressure, so the valve train will think the seat pressure is much higher.
Also, you might want the exhaust to open and close at a slower rate and max lift is not as big a concern because the exhaust cylinder pressures are way higher than the 1 atmosphere trying to fill the cylinder on the intake stroke.
No reason to be afraid of 1.6s.
I don't think there is such a thing as Aluminum shafts.
Yes...I was referring to a top of the line steel rocker like a T&d. Not a cheaper stainless set.
I don't think there is such a thing as Aluminum shafts.
Doorkicker
Well-Known Member
Ugh! I read this and I get a pit in my belly... I should have gone 1.6. We essentially have the same setup - your heads are a bit larger, I have the 240s.
Don't be me... go alum 1.6. When I upgrade this animal again (and I will)... I'm going with alum 1.6 rockers and never looking back. Steel is overkill, alum is way strong for street/strip and will take you far into cam/spring upgrades later on.
70ChargerRT
Well-Known Member
Yeah I’m using 240 heads, 1.6 HD Rockers. I think the rockers are aluminum but the shaft is steel. Don’t know a lot about rockers but that’s what I’m using lol
451Mopar
Well-Known Member
I don't know that aluminum alloy or treatment processes T&D use, but their aluminum rockers are tough! Mine even have a few dings from the pushrods from when the rocker stands failed, and they still work great.
gtxdana
Well-Known Member
While those T&D rockers are nice, they are way beyond what you need for the spring pressures you are running.
I prefer steel rocker arms, especially on a motor that is going to be run for hours on end, like on a long trip.
You could by a set of Comp Pro Magnum roller rockers, which would be more than adequate and have an extra $1900 to spend on other go-fast goodies over the T&D.
The only way to find out which rocker arm ratio would be best would be to book some dyno time and take two or three sets with you to test back to back.
ozzymaxwedge
Active Member
We run Hughes Ali 1.6 on our 500+ Indy head engines, they go to hell and back running in Drag week type events, they have been amazing .
cdr
Well-Known Member
THIS ^^^^^^^ I have the alum 1.6 T&D on my junker, LOTS of miles on them, so far so good about the same springs as the OP
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My cam was already specced for a 572 stroker "street/strip" engine, and I have longevity, reliability, and relative ease of maintenence as important aspects of the build.
I found the 1.6 T&D roller rockers were the ones B3E wanted me to use.
I'm also using the B3E valvetrain geometry correction kit.
I asked my builder if the 1.6 ratio was ok with him and got the "good to go".
I'm happy I'm getting a little more lift.
I found the 1.6 T&D roller rockers were the ones B3E wanted me to use.
I'm also using the B3E valvetrain geometry correction kit.
I asked my builder if the 1.6 ratio was ok with him and got the "good to go".
I'm happy I'm getting a little more lift.
fourgearsavoy
Well-Known Member
The valvetrain may be noisy with that much spring on a hyd. roller cam. I done a lot of research before I went to a solid roller -VS- hyd. roller. Talked to a few vendors and they both stated that even the best lifter can't tolerate the spring pressures recommended by the cam grinder.
As far as rockers go I prefer steel for something that is going to be driven for an hour at 3000 RPM like going to a show or race. I have had a set of 1.5 Isky rockers bushed by RAS going strong on my head Indy 493 for about 10 years now. My new rockers are bushed stainless 1.6 units from Speedmaster and I hope they last a while.
If budget is not an issue get a set of steel 1.6 rockers with bronze bushings and hard chromed shafts.
Gus
As far as rockers go I prefer steel for something that is going to be driven for an hour at 3000 RPM like going to a show or race. I have had a set of 1.5 Isky rockers bushed by RAS going strong on my head Indy 493 for about 10 years now. My new rockers are bushed stainless 1.6 units from Speedmaster and I hope they last a while.
If budget is not an issue get a set of steel 1.6 rockers with bronze bushings and hard chromed shafts.
Gus
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