Overhead-cam Engine

[Stallion]

What does this mean? I saw this being referred to in a spec list on an engine. And, if it's not this, what kind of engine could it be?

Thanks!

TR

 

[Stallion]

Anybody? I kind of just figured that it meant that the camshaft was somehow just located over the heads in relation to them. Is that right?

Thanks!

TR

 

[twiget]

Anybody? I kind of just figured that it meant that the camshaft was somehow just located over the heads in relation to them. Is that right?

Thanks!

TR

Pretty much. My uderstanding, is that there is two cam shafts per head. One for the intake valves, and one for the exhaust valves. The standard Corvette engine is a push-rod engine, with one cam shaft at the bottom, that moves pushrods up and down to accutate the intake and exhaust valves.

Jason

 

[90 Corvette ZR-1]

The LT5 that powered the ZR-1 is an over head cam motor. Instead of push rods opening and closing the valves the cams themselfs open and close them. The cams are located at the top of the motor above the heads.

 

[Stallion]

So the standard Vette engine isn't an overhead? I didn't konw that. I always kinda just assumed that the cam was at the top of the block. Now I know!

Thanks!

TR

 

[Tom73]

So the standard Vette engine isn't an overhead? I didn't konw that. I always kinda just assumed that the cam was at the top of the block. Now I know!

In the standard Chevy V8 the cam runs down the center of the block just above the crankshaft.

tom...

 

[Stallion]

Okay, I see now. Thanks!

TR

 

[Stallion]

"My uderstanding, is that there is two cam shafts per head."

So there are two cams in the V8s that our Vettes run? Or not? :confused

Thanks!

TR

 

[90 Corvette ZR-1]

on an over head valve motor (push rod) there is only one cam at the base of the V to drive the push rods

 

[twiget]

"My uderstanding, is that there is two cam shafts per head."

So there are two cams in the V8s that our Vettes run? Or not? :confused

Thanks!

TR

Sorry, I should have explained that better. In a Dual Overhead Cam (DOHC) motor, there are two cams per head. One for the intake valves, and one for the exhaust valves.

In the a pushrod motor (what's in 99.99% of 'Vettes) there is one cam shaft at the bottom of the motor that spins, and actuates the push rods which open and close the intake and exhaust valves. So a pushrod motor only has one cam shaft to run both the intake and exhaust valves.

Jason

 

[Stallion]

Okay, I understand now. Thanks!

TR

 

[JohnZ]

There are single overhead cams (one cam with both intake and exhaust lobes on it, just like the regular cam down in the block on a pushrod engine), and dual overhead cams, where there's an intake cam and an exhaust cam (like the 90's LT5 Corvette engine).

Most modern designs use separate (dual) overhead cams; they're more expensive, but they offer the capability of advancing and retarding the intake and exhaust cam timing separately with electronically-controlled hydraulic actuators based on engine operating conditions for improved torque, power, efficiency, and reduced emissions.

 

[Stallion]

I find it really interesting that things like retarding cams can help along torque and horsepower and all those sort of things. And if you have higher lift and lower duration on your cam, you get more low-end torque, rigth? Technically, why is this?

Thanks, John!

TR