454 Occasional Lifter Tick

[BigRandy]

My 74 C10 454 with 105,000 miles will occasionally develop a hard lifter clack after it's warm that will last for maybe a minute or two then go away. It's done it twice that I know of. The engine is smooth and quiet otherwise even when starting after sitting for days.

I don't know the full history of the truck but have service records from the original owner up to 89K when he sold it. I bought it with 103K miles and have put on another 2K, swapped it to HEI, new plugs, wires, fresh fluids and filters from bumper to bumper.

The engine is stock, and as far as I can tell it's never been open. The service records show it was in Wyoming most of its life whee it received regular oil changes with Quaker State 10W30. The truck is in S Texas now and I switched to conventional 15W40 HDEO with a Purolator filter.

The oil was a little dirty when I got it but not filthy black. I've seen a lot worse.

Oil pressure is 55-60 cold, 45+ on the highway and around 30-34 at hot idle in drive. Never lower.

Could it be the oil or does this sound like a lifter going bad? Maybe trash in the lifter caused by the HDEO loosening up some 44 year old gunk? I'm ready to change the oil again but if the 15W40 could be causing this I'll go with something else. Interesting note: The owners manual recommends 20W50 in hotter climates. Too bad the 20W50 today isn't the same as it was in '74.

She's an ugly old buzzard but I like her.