IMM Engines 408 build

ou812 said

Every now and then we have a lifter that does this, however usually it does it before we ship the engine. I put an honest 1-2 hours on an engine during break in, and tuning session at a minimum....I like to also try and let the engine sit overnight and resume testing the next day. I've found this really helps with things that might go wrong so we can make changes before we ship the engine. Sometimes you win, sometimes you don't...but I stand behind our engines, and if there's a bad lifter, we'll make it right!

Click to expand...

Dunno if this will help Mullinax feel any better, but the new Crane flat hydraulics my son and I put in his 340 were fine up front but developed a tick after a few hundred miles and at about 800 miles, one of them was deadsville. The bad one felt like yours: soft all the time, even after running. We could hear it in one side of the exhaust. (Off came the intake due to Edelbrock heads.) Crane replaced it plus another marginal one, no questions asked, so I think they see this regularly now.

So the mileage when it happens seems to be rather random; it can be fine out of the shop and then go many miles later; sounds like your situation.

I've put in a couple of dozen new hydraulic sets over 40+ years or so in a variety of medium performance engines, and never looked back at a single one until about 10 year ago, and it seems to have gotten progressively worse. IMHO, the 'tricks of the trade' for hydraulics have been lost or thrown out of the window, and it is part of the scene for hydraulics anymore and goes back to the manufacturing/design/materials selection. Sad to see it.

If I ever build any engines for others after I retire (low-po stuff), I may just refuse to warranty hydraulic lifters, they way they are now.