What is the difference between a solid lifter cam and a hydraulic cam and the term flat tappet..

 

While there are some difference in the actual camshaft lobes, the real difference is in the lifters. A hydraulic lifter has a hydraulic piston mechanism that compensates for changes in the length of the pushrod as the engine expands and contracts with heat, and for wear in the valvetrain. A solid lifter does not do this. This is why you have to adjust solid lifter valvetrains more often, because the parts wear. Flat tappet refers to a solid lifter without a roller. In reality, the lifter is not flat. It has a curved surface that rides on the camshaft lobe. This is done to reduce the contact pressure between the lifter and the cam. A roller lifter actually has a wheel on the end of the lifter to reduce friction and allow for more aggressive cam profiles.

A camshaft designed for a hydraulic cam will have a different profile than a solid cam. The big difference is at the very beginning of the ramp and end of the ramps. Other than that, the profiles should be the same.

I hope this helps. There are a lot of details involved in the valvetrain, and it would take pages to describe them all.

Ken

 

tap tap tap tap tap tap tap tap tap tap tap tap tap tap tap tap
click click click click click click click click click click click click click

lol sorry I couldnt resist.

 

 

solids shouldn't be making a huge Tap Tap or click click sound...If adjusted correctly they are quiet.

 

A lifter is a tappet is a lifter etc etc.
Solid lifters are either flat or roller; valve train lash (aka slack) must be adjusted.
Hydraulic lifters are either flat or roller; automatically takes up lash (aka slack) in valve train.

As said, flat tappet's face has a slight crown (dome) and flat tappet cam lobe has a slight angle to match lifter's crown; available solid or hydraulic.

Roller tappets have a rolling wheel than rides on cam lobe having NO angle; available solid or hydraulic. Most overhead valve GM production motors since about MY1987 have hydraulic roller tappets & cams.

 

Is there a major performance diff. between the solid n hydraulic......The reason I ask is that I read a thread were guys were knocking the H-flat tappet which is what I was advised 2 use in my 454 rebuild........I hope I didn't make a mistake..Thanx...Jerrylee///

 

Depends on what you are going to use the car for...solid lifters allow for higher revs. Hydraulic lifters can only rev so high before valve float.

If it is a street car, then hydraulic is the way to go....set the lash once and you are done...solids will have to be adjusted.

The 1970 454/390 came with hydraulic....never have to mess with em.

 

Thanx...my 77' 454 is a street machine..i'm using cc-xe268h.....hopefully she'll b on the road in a couple of weeks......

 

depends on how you defne quiet... My 64 has solid lifters and I have been adjusting them for 25 years myself...

No way can that engine at idel be confused with a car with hydralixc lifters...

Noise is NOT HUGE...but baby its there...and I love it almost as much as I like the sound of a gear drive...

Bob G.
64 72 76 79 & 98 Corvettes

 

But hydraulics are still good till 6500.

 

Yes they do make some noise but not much....The one thing that Solids do is make better Hgs at idle....they seem to have better throttle response...IMHO
You can use oil restrictors with solids, Im not sure if it's a good idea with Hydraulics,
Any thoughts on this?