Sounds like the cam isnt going flat, and the valve stems, pushrods and rockers are ok, but I dont know about the lifters. You need to track down exactly where the noise is coming from. A mechanics stethoscope can be a lifesaver, and even a long 1/2" hose can work really well. If you have a soggy lifter, drain a quart of oil, and pour in a quart of marvel mystery oil. Drive for 500 miles, drain the oil and throw in another quart. Dont get synthetic oil. Get regular dino oil. Dont throw in any additives either, except for the MMO.
If you want to clear out any varnish from the lifters fast, get some engine flush. There are a few different types. I use the one in a clear bottle. The ones that say "engine flush" are too much like water. It can be really hard on parts. The one I use says right on the bottle, that it wont thin out the motor oil. This is the safe one to use. Warm the engine up, pour the whole bottle of this in, let it idle for 5 minutes. Let the motor cool down...wait a couple hours. Fire it back up and let it idle for another 5 minutes. Do this one more time, and then drain the oil. Keep in mind that this isnt the instructions they give you. Ive found this will get the solvent all over every surface inside the engine, it will soak and loosen everything up, and then fire it back up to wash it all out. Do your oil change, change the filter, and throw in 5 quarts of royal purple 10W-40. I actually did this routine on saturday, and I cant believe how much quieter and smoother my engine runs. I ran nothing but royal purple in my 600hp cobra. I used to fire it up cold in the middle of winter and go tearing down the street, bouncing it off the rev limiter at 7500rpm through the gears. I really beat on that engine, and when I sold it, the compression was like new, and the car had emissions WAY cleaner than stock. Their claims of less emissions is totally true. All the tiny microscopic crevices get filled in with moly and it increases compression, stops blow-by and protects all the bearings. It also is like a mega detergent that cleans varnish and sludge out like nothing else. Ive tried every synthetic on the market and their stuff is the best. There are some punch and die assemblies I machined and built at work, and I always had a guide bushing wear issue, using mobil1 synthetic grease. On a new assembly, I used Royal Purple synchromax for manual transmissions. Just a drop on each guide. That thing ran 24/7 for a week and when I tore it down, it didnt have a single scratch on it. Im a big believer in their products. Ive had the worst luck by far with mobil 1. When I changed my oil the other night, when I pulled my filter, as usual some oil dripped all over my tie rod joint. I always wipe it off but the greasy road tar has always stayed on it. I ran the rag across this joint a couple times, and all that sludge literally melted off and it looked like fresh metal. I couldnt believe it. Like ive said in old posts, in my cobra, mobil 1 would drain out looking like nasty tar at only 4000 miles. At 8000 miles, the royal purple would drain out looking almost brand new. And the inside of my engine was immaculate, in spite of the fact I didnt change the oil as often as I should. I would go 10,000 miles at times without even changing the filter.
