mechanical vs. hydraulic cam
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mechanical vs. hydraulic cam
I have heard that mechanical or solid cams are better for overall performance but the reason hydraulic is preferred is because of noise and maintenance. How noisy is the valve train really and how often does it have to be adjusted? I have heard like 1 or 2 times a year. How hard is it to adjust? If mechanical and solid roller cams are better, why dont more use them? What is the diference between a mechanical and solid roller cam and what is best for performance?
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From: Escondido, CA
mechanical vs. hydraulic cam
The main reason people don't like to use solid lifters is because of having to adjust them. You have to go in and set the rocker arm to valve lash very often if it is a daily driver. Almost once a week if you have a lead foot. You would end up having to adjust the solids anytime you have a lot of slack in them. ie... the rattling noise. Any time that you use a roller lifter, whether it be a hyd or solid, you are reducing the amount of friction that is on the valve train, meaning more HP and TQ. Hyd lifters don't need adjustment if you set the preload right. Personally I am going to run a hyd roller cam in my engine once I save up the $340 for the cam and $430 for the lifters. The conversion isn't cheap. The advantage is maybe a whopping 40 ft-lbs of TQ and a few HP but the way the engine rev's to life is the differance. Hope this helps.
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From: Nevada
mechanical vs. hydraulic cam
I've used solid lifters in a variety of engines, including FEs and 385s, and once the engine is broken in, they require no more maintenance than hydraulic lifters. But I always check the preload on hydraulics when changing plugs as a preventative maintence item. And retorque the intake manifold.
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Joined: Jan 2000
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From: Crooked River Ranch, OR
mechanical vs. hydraulic cam
Solid lifters make more noise than hydrulics because of the slack that has to be taken up in the valve lash each time the valve opens.
The biggest advantage for solids are they can rev higher without valve float than a hydraulic and for drag racing they are more consistent when trying to run within a few hundreths or thousandths of a second repeatedly. Figure hydraulic upper RPM limit to be around 6500 and solids over 8000 RPM when the valve train is setup correctly.
Solid roller cams should be considered "race-only" as the very high spring pressures are hard on parts. They do make more HP but the initial cost is high and your valve train longevity is short. I used to go through a minimum of two sets of valve springs ($250 set) and usually a titanium retainer or two each summer...but then my 514 was spun to 7600 RPM.
As far as adjusting a solid cam, I only need to adjust once a summer on my blown drag car but the engine never sees more than 6500 RPM. A street driven engine shouldn't need much more than that on average. Deen
The biggest advantage for solids are they can rev higher without valve float than a hydraulic and for drag racing they are more consistent when trying to run within a few hundreths or thousandths of a second repeatedly. Figure hydraulic upper RPM limit to be around 6500 and solids over 8000 RPM when the valve train is setup correctly.
Solid roller cams should be considered "race-only" as the very high spring pressures are hard on parts. They do make more HP but the initial cost is high and your valve train longevity is short. I used to go through a minimum of two sets of valve springs ($250 set) and usually a titanium retainer or two each summer...but then my 514 was spun to 7600 RPM.
As far as adjusting a solid cam, I only need to adjust once a summer on my blown drag car but the engine never sees more than 6500 RPM. A street driven engine shouldn't need much more than that on average. Deen
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From: Nevada
mechanical vs. hydraulic cam
Not hard, just tedious. Most shop manuals cover adjusting hydraulic lifter preload on a cold engine. Solid lifters are the same type of a job, only using a feeler gauge to establish the required clearance between rocker arm and valve on a hot engine (operating temperature) instead of rocker arm and pushrod as with the hydraulics.
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