lifters

[shawnxj]

ok i was watching a speed show the other day and they were using solid lifters on i think it was a 383 but don't remember for sure and it got me thinking. why are we using hydraulic lifters instead of solids?. wouldn't solids be more reliable and easier to deal with?

[SilverXJ]

Solids need an adjustable valve train, are noisy, and require frequent adjustment.

[Alex22]

Solid lifters are used for race or street-strip engines because they can hold up to a stiffer valve spring and they are not limited by how fast they can refill with oil to keep the proper preload on the valve train (about 6400rpm)

not practical for a low rpm daily driver.

[5-90]

Solid lifters are used for race or street-strip engines because they can hold up to a stiffer valve spring and they are not limited by how fast they can refill with oil to keep the proper preload on the valve train (about 6400rpm)

not practical for a low rpm daily driver.

Alex - solids are simple metal slugs, and don't "refill with oil" at all. You have to figure out how to get oil up to the valve gear separately - often, shaft-mounted rockers are used, and the oil is pressure-fed up along a screw bore (or by way of a hollow screw, akin to the screw in a "banjo" fitting.)

OP - as mentioned, solid lifters require frequent adjustment, are noisy, and require a certain set operating clearance ("lash") in the valvetrain. Hydraulic lifters can be run with "zero lash" - which keeps the valvetrain nice and quiet, and saves us having to figure out if that knock we're hearing is normal or not (hydraulic tappets don't knock - so if you hear it, there's something wrong. A very slight "tap" is normal - but it's not something you're going to hear over an engine idling. A mechanic's stethoscope played down the passenger side of the AMC six will show you what I'm talking about.)

It's not worth the trouble to redesign to accommodate an adjustable valvetrain and "slug tappets" (what I first learned them as,) so don't bother. A hydraulic valvetrain is actually a bit more reliable and user-friendly anyhow, so what's the problem?

A laudable idea, and I'm sorry to shoot it down - but I've had to deal with solid tappet valvetrains before, and I honestly prefer not to...

[shawnxj]

good to know