Hydraulic lifters

Hi Pancho,

The Chevy 454 stock, plain vanilla,marine engine uses hydraulic lifters, not solid lifters, therefore the valves adjust using the zero lash, plus another 3/4 of a turn tight. You would not adjust these valves with a feeler gauge. A good shop manual can explain it in better detail than I can here, but you can perform the adjustment with the engine not running, which is a lot less messy. You could have a lifter sticking but not necessarily out of adjustment in which case the top end lubricants might help. Some people use a quart of ATF to loosen them up, but I would agree that MMO would be better. There a lot of opinions about what home remedy works best. Has the engine been sitting unused for a long time? YOu could also have a cam lobe wearing out causing the excessive lash. Or you could have a valve sticking, which is the worst case because it will contact a piston top breaking stuff. Not good. Or the ticking could be something else entirely such as a wrist pin. Try killing ignition one wire/cylinder at a time and see if the noise changes pitch or goes away. A valve train noise generally would not change if you cancel the ignition on a cylinder.

At any rate do the simple things first, MMO in oil. Give it long enough time to get in there and work. Check compression to see if you have a low cylinder due to a stuck valve. Pull the valve covers and roll the starter with no ignition and carefully watch each valve looking for sticking valves or a valve not opening much or none.

Or do what a lot a people do. Ignore it until it blows!

Good luck, Greg