im fairly new to engines and im looking around for a set of heads to get for my 350. i was wondering what the difference between a hydraulic and roller cam was and why you have to have a different set of heads or matching heads. i was the rockers have to match up. how can you tell and whats the difference between the two? which one would be better off to use? also on a set of heads, whats is the best intake/exhaust and cc to have? i appreciate your guys help.

 

Ok, here we go... Hydraulic flat tappet (hydraulic cam) lifters ride directly on the cam lobe, generating some friction. Hydraulic roller lifters have a small bearing on the bottom of the lifter body that rides on the cam lobe, reducing friction. There is no difference in heads between the two, except for pushrod guideplates. If you are running a roller lifter, you need pushrod guideplates. If you are not running a roller, you dont need them. THERE IS ONE EXCEPTION! If you are running a roller cam, AND have self aligning rockers, you DONT need pushrod guideplates.

The guideplates are needed to keep the tip of the rocker centered over the valvestem on roller cam motors. As far as telling apart the two different cam setups visually...you cant. You would have to reference casting numbers on the block as well as casting dates to determine if it is a roller motor or not. I believe that all chevy small blocks 87-up are rollers, but I could be wrong.

I hope this helps!

 

It's pretty easy to tell the difference between lifters. If it's a roller lifter, it has a bearing that "rolls." Regular lifters have a flat surface. Rollers are better performance-wise because they can achieve greater lifts faster.

 

Also...... there is no difference in the heads as far as which is for a roller cam and which isn't.

What DOES matter is the valve springs. As fast89rs said, roller cams open the valve quicker than a flat tappet cam. Because of the quicker "snap", stronger springs are needed to achieve higher RPMs and keep the valves from "floating."

The only difference in the "pre-1987" heads and the "1987 and up" heads (other than Gen III heads and Vortec heads) is the angle of the four center bolt holes for the intake manifold. GM figured out that drilling them at a 72* angle (in relation to the gasket surface) instead of a 90* angle, they leak less, if at all.

So..... I.E...... when the newer heads (87+) are on the engine, the four center intake bolts go straight down, or 90* to the ground below.

 

Sorry, when I said your cant tell the two different setups apart visually, I meant looking at a complete motor assembled. There are no visual clues externally on the motor itself, but of course, the cams and lifters look very different. Sorry to sound like a dumb*ss

 

You cant tell with the motor completely together, but if the intake is off, you can see the stuff that keeps the lifters straight. I dont know what this stuff that alligns the lifters is called though.