Isky E-4 , hydraulic equivalent ?

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rustytoolss

rustytoolss

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Seems everyone likes the Isky E-4 soild cam for their 273's .I'm not well versed in camshaft selection. At this point I would like to run a hydraulic cam. I read that a solid vs. hyd cam are two different animals. (but don't know much about that either).
So if the Isky E-4 is such a good cam...What would be the hydraulic equivalent ?
Who makes an E-4 hydraulic type cam ( part #s )
Big question here will a cam of this size kill my vacuum & mileage ?
 
Generally speaking, to get the same out of a hydraulic, you want about 10* less duration @.050 compared to the solid, all else being equal. Because of the lash and the lobe differences, a solid with similar specs will "act" smaller than they hydraulic.
 
Isky makes the E-4. Give them a call, I'm sure they could steer you in the right direction. Sometimes mileage can go up if the engine works better at your cruising RPM and you need less throttle to stay there. That is where a vacuum gage is handy. E-4 has plenty of vacuum.
 
66fs said:
Isky makes the E-4. Give them a call, I'm sure they could steer you in the right direction. Sometimes mileage can go up if the engine works better at your cruising RPM and you need less throttle to stay there. That is where a vacuum gage is handy. E-4 has plenty of vacuum.
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So what kind of vacuum are you pulling at idle ?
 
RustyRatRod said:
Generally speaking, to get the same out of a hydraulic, you want about 10* less duration @.050 compared to the solid, all else being equal. Because of the lash and the lobe differences, a solid with similar specs will "act" smaller than they hydraulic.
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Rusty, don't you mean 10 deg. more?
 
rustytoolss said:
So what kind of vacuum are you pulling at idle ?
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I truly can't remember, and my 66 is at our retirement house in South Carolina. I feel like 15 or 16 but that is a guess. I'm sure I will not get down there before you need to know. Hey ToolmanMike, Is your 66 tucked away for the winter? Do you remember idle speed and vacuum on your 273?
 
I think my vacuum is a bit low because I advanced the valve timing 2degrees to give me more bottom end. I don't think it made that much difference.
 
toolmanmike said:
Rusty, don't you mean 10 deg. more?
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No. A hydraulic with the same duration @ .050 as a solid will act about 10* bigger than the solid. So if you want a hydraulic to be about the same as a solid, you need to choose one with duration @ .050 figures about 10* less.

In other words, a solid with 240 @ .050 is about the same as a hydraulic with 230 @ .050. Get it?
 
RustyRatRod said:
No. A hydraulic with the same duration @ .050 as a solid will act about 10* bigger than the solid. So if you want a hydraulic to be about the same as a solid, you need to choose one with duration @ .050 figures about 10* less.

In other words, a solid with 240 @ .050 is about the same as a hydraulic with 230 @ .050. Get it?
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This is what I've heard when comparing a hydraulic to a solid. I'm pretty sure that this is because they do not figure in valve lash when they provide the measurements for solid cams.
 
73Scamp318 said:
This is what I've heard when comparing a hydraulic to a solid. I'm pretty sure that this is because they do not figure in valve lash when they provide the measurements for solid cams.
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Yeah. Exactly what I said in my first post up there ^^^^^^.
 
rustytoolss said:
So what kind of vacuum are you pulling at idle ?
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I'm pulling 14 inches steady at 700 rpm. Timing at 0 degrees BTDC to be able to run 93 octane fuel. I know this is very old but I was just down in SC and remembered to check it. Maybe it will help someone.
 
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