What's the difference between a hydrolic cam ,roller cam, and flat tappet? whats the difference in performance? Which is the best for high performance? I've also seen some cams on ebay reguarding the LT1 cams to be hydrolic and some non hydrolic, which is right?

Thanks

 

<b>Hydraulic</b> = uses oil pressure to keep tension on valvetrain.

<b>Solid</b> = solid hunk that requires different valve adjustment and a lot more often. Usually used for high RPM (+6500) racing apps only.

Each of these options are available as flat tappet or roller.

<b>Flat tappet</b> is just flat steel that slides over the lobes on your cam. More friction.

<b>Roller</b> has a bearing on the bottom of the lifter that rolls over the cam lobes and allows for a much more aggressive angle on the lobes which opens the valves to full lift faster and much less friction. Roller cam also requires retainers of some kind to keep the lifters straight in the hole.

Less friction and faster valve opening = more hp on the same duration and lift.

 

This is probably a dumb question, but I'm gonna' ask it...

On my 92, the cam is hydraulic roller... right?

can i replace it with a regular hydraulic cam if I buy the approprite lifters?

I ask because a hydraulic cam kit with lifters and all is about the same price as just a hydraulic roller camshaft without lifters. hydraulic roller lifters are like $200 for a set by themselves.

I may just be reading all this camshaft stuff all wrong, but it would really be nice if someone could clarify the hydraulic roller/hydraulic regular thing for me.

One more thing... If I did do a cam swap and just put a regular hydraulic cam in and not a hydraulic roller cam, would I lose alot of performance?

thanks

 

Recently I learned that solid lifers are better for high rpm because they are lighter than hydraulic lifters. Never thought about it that way, until I read that recently. It does seem to me that you'd always want a roller lifter (or rocker), barring the price difference. Hydraulic or not depends on the application...

 

if i were you i would run a roller cam. when you buy a hydraulic roller camshaft you dont need to buy new lifters. for instance if you bought my ZZ4 roller cam for ~$120 then you could use you stock roller lifters w/o any problems. i dont know if you can just throw a hydaulic flat tappet lifter cam and lifters in your engine but i bet you can. but why? i have a hydraulic flat tappet cam, but that is because i have a 1974 block and i didnt want to try to mess with roller cams. so even if you did go buy a hydraulic flat tappet cam and lifters for ~$100 you should have just popped for a roller cam.

 

Also hydraulic lifters tend to "pump up" in higher RPM's (even the anti-pump ones still do), usually past RPM's of 6000+. Obviously solid lifters will not "pump up".

 

I've had a couple cars with solid cams, albeit the funnest one was a '72 Nova.

It had a 355, 462 Camel Hump heads, Holley 750 DBL-PMPR, Holley high rise intake, and a Crane FireBall cam. Adv. dur. was 302* @ .510 lift. Not SUPER radical, but FUN!!!!!! 7500 RPM no problem

I didn't do that a lot (probably once or twice) since the crank and rods were stock cast units. But it wasn't abnormal for me to wind her to 6500. Of course it had 1.6 full rollers, guide plates, and hardened PRs so the valve train had no problem at all.

I need to stop talking about it ..... I miss that car

This is my first car with a hyd. roller cam. From what I've read and seen, it's a blessing in disguise. :rockon:

AJ

 

A flat tappet cam can be used in a roller block, but like you say, what the h@ll for?

 

Thanks for all the input... I guess I'll stick hydraulic roller when the time comes

 

brharris27370:

Today I disassembled an old HYDRAULIC lifter: It's like a cylinder with a small piston at top and a little hole in it. But, since that I see the piston can't moves into the cylinder I can't understand how the hidraulic lifter works with oil pressure. For me, with oil or without oil into the hydraulic lifter is the same piston position, then pushrod, rocker arm and valve position. ???????.

I'm a little confused.

Thanks for 1 reply.

 

If you took a hydraulic lifter apart, then you should have found a spring inside also.

The spring helps keep tension on the valve train when the engine's off, but once the engine's running, the hydraulic pressure is very high.

There should be a little hole on the side of the lifter. That's where the oil goes "in and out". When the lifter rides the cam lobe and it's on it's way up, the resistance from the valve spring will compress the oil inside the lifter. This takes the shock out of the movement.

Perhaps you took apart a solid lifter?

AJ

 

Mmmmm,

If the spring keeps tension on the valve train when the engine is off, then the max. way up (or "high level") that the PUSHROD can be, with valve fully closed, is the same for a hydraulic lifter with 1): spring and engine off, or 2): oil into the lifter and engine running.

The only difference will be the pushrod PRESSURE against the lifter with oil. I'm right??

Conclussion: No differences adjusting the valves with engine off or running?

 

Right. No difference.

I've never adjusted the valves with the engine running. I think it's just a phobia I have or something. I just can't bring myself to do it for some reason.

Anyway... some people will tell you that doing it with the engine running is the "best way", but I can't see how other than it might be faster to do it that way.

AJ

 

Yes,

Some people says: "when the noise stops..., then turn the rocker arm nut 1/2 additional turn or so".

But, with the engine running the problem is: Too many noises, sounds, movements, etc., like: tick, tick, clank, clunk, tung, ruuuunnn, pot, pot, pot, clink, clink, hoooo, and others like waaaaaahhhh, when you touch some hot part.

I prefer the engine off, without noises nor movement, exhaust gas, hot parts, etc.


Thanks,

 

The clack that a rocker arm makes is very distinct and you will pick up on any sound that is well just wrong with an engine.

I tried every single way to tighten the rocker arms to get the proper valve lash and I ended up using the with the engine running back off till it clacks, tighten to remove clack and then give it a 1/2 turn. Every other way made the engine feel weird as I was driving/starting the engine.

Well the proof is in the 1/4 mile times, I got an extra 2 tenths out of it and consistently break 90 mph trap speeds. The engine's been running great for the last 500 miles, no oddball sounds and checking on the rockers seem like they don't mind the adjustment.

 

the sound of a clicking rocker is very distinct. What I did was tighten them all so they stopped...most were to tight at first then i backed them off one by one... then i loosened one at a time until it ticked and turned it another 1/2 turn...worked well...ran good for awhile then i broke a brand new valve spring in 3 places and thought the motor was dead. started tearing into it and figured out what it was and decided to pull the 305 anyways