I have a 61 Dynamic 88 with the 394 2bbl. Just recently it started making a fairly loud lifter/valve noise but only at highway speed around 70mph. Sometimes all I have to is get off the highway and cruise around 50mph and it goes away, other times I might have to let it sit for 10 minutes and then it's fine. If I cruise the back roads around 50-55 mph It will go all day without any noise at all I'm not a mechanic but I'm not mechanically challenged either so I was thinking possibly a gummed up screen on the oil pump or something like that perhaps? Any thoughts on this would be greatly appreciated thanks, Jeff.

 

My old 63 394 would go 3000 miles between oil changes without a noise any miles after that and a lifter would stick. Try a oil change and a pint of your favorite upper valve train lubricant and see what happens. Sticky lifters are common on all first generation Old's V8's.... Tedd

 

Sorry, forgot to throw that in there, I did an oil change last week and threw some Wynns lifter quieter in it.

 

Do you know what your oil pressure is? With a gauge you can monitor what its doing when it acts up. How much crud has built up under the valve covers?

 

I haven't pulled anything apart yet and I was thinking a gauge would be a good idea, I thought I would do a little fishing for ideas before I get the tools out.

 

What weight oil are you using? Factory spec was 20 weight but a straight 30 weight oil should work for your 394. Sure it's lifter noise and not rocker shaft?

 

If it is lifter noise and not rockets then you should use E.O.S. engine oil supplement which was designed for the 394 lifter noise. I add it when I do an oil change and it works, the product is available here at any GM dealer and any AC Delco dealer/jobber parts supplier.
Steve