can someone explain the difference ..

[LoudLT1]

between a roller camshaft and a hydrollic camshaft?
what type does LT1 fall under?

eddie

[ConElite]

between a roller camshaft and a hydrolic camfast?
what type does LT1 fall under?

eddie

If im not mistaken You have Hydrolic Roller cam. The difference is that where the pushrod connects to the lifter. The hydrolic ones have a spring that allow for a little travel for the pushrod to go into the lifter. The Roller ones are Solid I believe.

[Injuneer]

There are two kinds of valve "lifters"..... solid, and hydraulic. (forget about "roller" for now). The "solid" lifter is a simple cylinder of metal, that sits on the cam lobe, and accepts the bottom of the pushrod at the top of the lifter. That type of lifter produces a valve train that requires "slack"..... a space in the system so that the components of the valve train are not always in contact with each other. The slack ends up being the clearance between the tip of the rocker arm and the top of the valve stem. That clearance is set to a specifiec gap (in the range of 0.012-0.018") using a feeler gauge while adjusting the rocker fulcrum.

A hydraulic lifter adds a small hydraulic cylinder to the valve lifter, immediately under the bottom of the pushrod. That hydraulic cylinder uses oil pressure to expand the lifter, and hold the valve train components in constant contact, eliminating the "clearance". This eliminates the need to set the valve train clearance periodically, and eliminates a lot of mechanical noise associated with the clearance periodically being taken up as the pushrod rises. The hydraulic lifter still needs an initial adjustment to put it into the correct operating range.

Your LT1 has hydraulic lifters.

So far, we haven't mentioned the "roller". That's a separate topic. A lifter can either use a hardened flat surface to ride on the cam lobe, or it can be fitted with a small roller that rides on the cam lobe, eliminating a lot of friction. You can use a flat surface or a roller with either a solid lifter or a hydraulic lifter. Your LT1 has a "roller" on the bottom of a hydraulic lifter.

I don't tnink anyone uses a "flat" lifter any more.... the rollers have gotten a lot more reliable than they once were. Few production cars use solid lifters, because of the noise and high maintenance. The trend toward buiulding an engine that can be "sealed" for 100,000 miles rules out solid lifters. The advantage of using a solid lifter is the ability to run the engine at higher RPM. A hydraulic lifter will eventually not have enough time at high RPM to release the hydraulic pressure as required and will "pump up" holding the valve open. Additionally, solid lifters are often used with very high lift camshafts, because these cams require beefy valve springs with high spring constants, and the pressure of the spring can be high enough to "collapse" the hydraulic system in the lifter.

My stroker uses a solid roller camshaft. It allows the engine to operate at 7,000+ RPM. But, the related mechanical noise pretty much rules out the use of the knock sensor.

[ConElite]

Thats exactly what i meant.

[Mark B]

Great explination guys. I have always wondered what the difference was.

[Joe 1320]

And that roller lifters will allow a slightly more aggressive cam to have the idle characteristics of a more mild cam.

[LoudLT1]

thanks injuneer,
great info
thanks again,
eddie