krill

What is the easiest way to find out if its a mechanical or hydraulic type of camshaft/lifters in a sbc 350? I dont know what year it is from but it is rebuilt to a 355 with a holley carb and edelbrock intake manifold, its sitting in a 1978 caprice but its not the original engine.

Its got a tick/knock coming from the valvetrain area when letting off the gas, its not there when accelerating.
I want to adjust the rockers to see if it helps but I dont know what type of lifters and camshaft is in there!

Thanks

ZONES89RS

iTrader: (25)

Pull the valve covers and see if you can get a feeler gauge under the rocker on the valve tip. If it has self aligning rockers, it is a flat tappet probably with hydraulic lifters. If you can get some lash reading on them, then it is a mechanical.

fleetmgr

Usually you can tell just by listening. A hydraulic valve train is usually silent, with a solid valve train there is usually some noise as there is clearance being taken up at every valve when the cam comes around.

ZONES89RS

iTrader: (25)

If it has a big enough cam, it can be hard to tell. I have heard some noisy hyd cams, but they were usually roller.

nlawson6.0

iTrader: (26)

mech lifters have a snap ring on top. hyd has a small bar in the shape of a u

ZONES89RS

iTrader: (25)

We are assuming he doesnt want to pull the intake, he didnt specify.

krill

Thanks for the help guys! Right now I would rather not pull the intake and just try to adjust the rockers first to see if it helps, if it doesnt we are prepared to pull the intake and see whats going on and maybe replace the lifters.
I think its a pretty big cam because the idle is set higher then normal and it sometimes stalls and dies when you put it in D.
Another question, if its flat tappet lifters you want to replace both the cam and lifters right?

ZONES89RS

iTrader: (25)

New lifters are OK, but a new cam and lifters is a more direct way to make sure everything will be fine.