quick question about the valvetrain

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Nov 23, 2004 | 06:53 PM

supasam

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From: New Orleans

quick question about the valvetrain

Which is better for performance applications, solid or hydraulic, and which part of the valvetrain is it that is actually hydraulic? Is it the connecting rods? If so why does everyone refer to them as lifters but only when comparing them to solid type, uh, or is that just me?

Is it hard to adjust the heads like you do on the solid ones? Do I need a really good torque wrench or will my cheapy from the parts store do fine? Or should I just go with the hydraulic ones? Thanks!

-sam

Nov 23, 2004 | 07:58 PM

Daijin

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Solid refers to the lifter, and they are usally better for performance. You just have to stay on top of valvelash.

Nov 24, 2004 | 02:43 AM

supasam

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Ouch, actually, I meant pushrod, not connecting rods, ie the ones in between the rockers and the cams. What I don't get is where the hydraulic part comes into play. The rods are still solid, right? Does the hydraulic action just take up the lash? And thats it? or are the rods somehow like two parts in a cylinder and theres oil in between that acts like some sort of hydraulic piston inside of the block its'self? Now that I word it out like that it just sounds crazy, so I'm thinking the pressure from the oil takes up the lash in the spaces between the pushrods and the rockers? That makes sense, but why would you take a performance hit for something like that?

-sam

Nov 24, 2004 | 09:20 AM

beartracks

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From: Albuquerque

Hydralic lifters are like little shock absorbers. They take up the slack in the valve train and make it quiet and are generally better for low/mid range torque on the street. Everthing else in the valve train is solid.

Nov 24, 2004 | 09:29 AM

Mike G

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From: Littleton, CO

Quote:

Originally Posted by supasam

ie the ones in between the rockers and the cams. That makes sense, but why would you take a performance hit for something like that?

-sam

Cam drives the lifter, pushrod sets in the lifter and actuates the rocker which moves the valves. If you have hydraulic lifters, they fill with oil and as mentioned, act as little shock absorbers to keep everything acting smooth and quiet. These provide for a little more room or play in the valve train, hence the lowere performance. The solid lifters do not fill with oil and require occasional adjustment to keep everything working smooth. Without the room for play, they provide for a tighter tolerance in the system and produce better performance. Of course if you go from a hydraulic system to a solid system, you may need to modify the oiling system in your block...

Just $.02's, --Mike