So I haven’t changed out my hydraulic flat tappet cam in 15 years. Just wondering what everyone’s doing these days prior to new lifter installation? I’ve seen some people just soak them in oil overnight and I’ve also put the lifters in a cup of oil and push the plunger down with a pushrod to get them to suck oil inside. Anything better than the other short of making sure they have a lot of lube on them before initial fire up. Craig
I was of the same school of though as you. But read somewhere recently not to do that. Last set I installed a few months ago just put the break in paste on the bottom of the lifter, some assembly lube on the sides and dropped em in the holes. Removed the center valve spring and did the butt puckering 20 min break in run.
When I swapped out my roller lifters, I soaked them in oil overnight, and installed them the next day. I did NOT push the plunger down. The lifters get pressurized oil right away. They will pump up very quickly. For flat tappets, yes for the moly paste on the cam lobes and lifter bottoms. Probably wouldn't hurt to run some break in oil. This stuff is really good, https://www.amazon.com/Gibbs-Driven-Racing-01806-Break/dp/B002MTMLSG
As the Wizard says....do not pump them in oil. I did that years ago and valves hung open at initial startup....not good.
Do not put assembly lube on the sides of a flat tappet Lifter, it needs to rotate immediately just oil on the sides! Assembly lube on the bottom only!
When it's me, I pump the lifters with ATF from a pump-style oil can. This allows me to verify that the lifter will flow oil to the pushrod seat, AND allows me to do a quickie check of leakdown rate. "Soaking" lifters does nothing useful. Dunking them in oil and pumping the plunger takes ten times as long as just using the oil-can to pump 'em. I have better things to do with that time and effort. Yes, you then need to be fairly careful when setting lifter preload. Go slow, so the valve isn't pushed open before the lifter can leak-down. If you're using moly-paste based lifter and cam-lobe prelube, change the oil filter after 20 minutes. Moly paste can plug an oil filter in a short time. I use cut-open valve covers, and a paint stripe on the pushrods to verify that the lifters are spinning at start-up.
I install the heads, mock up the cam, lifters, rockers and adjust the rockers dry. Then I remove the rockers, pushrods, lifters and cam keeping everything in order. I make sure the rotating assembly is ready to fire #1 cylinder. I lube the cam lobes and bottom of the lifters with the lube supplied with the cam. I lube the valve stem tops and both ends of the pushrods and assemble the valve train. The assembly is not turned from this time until the engine to be started. I finish assembling the engine and prime the oil pump continuing until there is oil coming through all pushrods into the rockers arms. The engine is now ready for the distributor and to be started for the 20 minute breaking process.
I took mine apart one by one and cleaned them, there wasn't necessarily grit in there but the rag was not exactly clean after giving the plunger a quick wipe.
