Just came across a YouTube video on lifter modifications from Delta Cams. Makes sense to me maybe this is the key to eliminating and or greatly reducing cam/lifter failures. Dan
So, in a nutshell, he’s increasing leakage past the lifters to get more oil to the lobes. Have we been responsible for destroying cams ourselves, by trying to restrict top end oiling and the subsequent drain back of oil to the pan so much that we have limited the splash oiling of the cam and lifters? Maybe a worn older block isn’t such a bad thing after all…
I have a set of Johnson solid lifters that had a tiny hole on the face of the tappet that would accomplish the same thing. Yes, the new stuff needs all the help it can get.
The hole in the face is counterproductive. We tried that on a Diesel back in the 1970s. It didn’t work. We then looked at the tribology at the interface of the lobe and lifter face. The rotation of the cam against the lifter creates a hydrodynamic wedge, and the pressure in this hydrodynamic wedge is in the tens of thousands of psi. (Look up hydraulic wedge). The hole actually flows backwards, up into the lifter instead of to the cam interface when the engine is running. We ended up putting a lifter with a silicon carbide face into production for that engine to solve the spalling issue. Subsequent engines were developed with roller followers instead of flat tappets. The rollers let us run higher valve acceleration rates for better performance without violating surface stress design criteria (hertz stress) at the interface.
I bought the Crower version with the tiny slot down one side to go with the Comp Cam in my new 389 Pontiac. I think the Crower slot goes all the way down. I kinda like that their little flat stops short of the cam wear surface. Either way it seems like a long overdue improvement.
The Crower cam savers are good lifters, I've install quit a few of them with good results. Rhoads lifters have had a slot for the same added oil to the lobe area for years now.
I saw that also. He did say that it helped but didn't eliminate the failures. So many unknowns with people's break in procedures to consider.
Upon more reading it sounds like many have been making a narrow shallow grove on lifters for years with good results some report noisy lifters afterwards. Dan
He mentions in the video he doesn't like the idea of any holes in the lifter surface that touches the cam lobe. I think that extending the tiny flat down all the way wouldn't hurt the cam surface, but not sure I want to test it on an engine rebuild myself. But I'd definitely try the modification they're doing if I ever build another flat tappet camshaft engine build.
Use Johnson HyLift lifters, good quality ***embly lube and reasonable spring pressures and lobe profiles. It's human nature to want it all; low prices, high-intensity lobe profiles, higher rocker ratios, higher spring pressure, higher RPM. Not possible to achieve it all. jack vines
Anyone get a good look after the lifter was modified? It looked to me like it was done on the “corner” of a stone on a bench grinder, the way it tapered. Hey, if it helps, heck ya.
comp cams part number 5001 tool cuts a small groove from the oil gally down to the lifter and supplies a stream of oil to the cam just before the lobe pushes the lifter up the only problem is it is used before ***embly and its a bit pricey but you will be everybody's friend
The Comp Cams lifter bore grooving tool has been around a long time. I have had one since the mid 80's. Works well if you position the slot per the instructions. Down side is you have to do it before ***embly. The Delta relief slot is ground, several manufacturers sell lifters with a milled slot. And several manufacturers sell the EDM cut hole on the lifter face. They are all an improvement over doing nothing. If not using a roller cam, I use one of these mods on any flat tappet cam I install.
This whole cam/lifter failure thing intrigues me, not because it happens but because it happens so often anymore. I’ve been reading and studying this problem for a little while. All kinds of theories and ideas on the causes. A few things come to mind: 1. Does the grove or flat help, I can’t see how it hurts. @Blues4U youre thoughts? 2. Cam ***embly lubes are essentially the same - some better than others I’m sure but I can’t believe this is the cause of early failures. Same with oils. 3. From what I’ve read many have their lifters resurfaced old and new alike. @chicken , @PackardV8 , @73RR Any thoughts on this? 4. Many blame spring pressure, I don’t think recommended pressures have changed. I do think using the lowest values needed is good practice. 5. Break in procedure this hasn’t changed at least since I was a teenager. As a matter fact I know many who just oiled up cam - often with STP - fired it up and ran with no problems or at least not for thousands of miles. Dan
Part of the issue is the ramp profile designs have changed over time. On some of the newer profiles the opening rate is more aggressive due to either performance or sound goals. When in doubt, lower pressure valve springs for the break in run are your friend. The time and effort to change them out after the run is a lot less than changing a cam. Also, if you choose to use a higher viscosity oil for break in consider using a oil pan warmer before start up. Every oil has a operating temp where the additive package performs best. You won't get there with the warmer, but it will improve initial flow. The combination of a cooling system heater and oil pan heater is about as proactive as you can get. But the biggest underlying issue is during ***embly you didn't confirm that the lifters spin easily in the lifter bore.
This is the route I took when rebuilding my flathead. Heard of all the horror stories with off-shore stuff and said no way was I going take a chance after investing all that time and money. Was spendy, but was worth the peace of mind
My only question in my mind is why aren't all lifters made this way if it stops cam/lifter failures? You'd think every maker would only supply lifters done this way if it cures the problem up?
I’ve farted around with groved blocks in a couple of engines using small files. Trick is not too deep, not too wide. I like it better because you don’t have to wait for the lifter to be in the right spot before it oils the lobe.
My son and I built flat tappet iron cams (rules mandated) for his dirt track engine. From 358” to 422” and never lost a cam or lifter in 15 years. Only the last 2, one with Isky lifters and one with Comp lifters had a hole in the bottom of the lifter. The Iskys was off center and the Comp was in the center. The Isky cam did have a special process or cast metal I can’t remember the name of but we still never lost an engine do to a cam related failure!
I'm still building engines with flat tappet cams. I agree that modern aggressive lobe profiles are harder on the cam/lifter interface than older, slower ramp designs. I also agree with using only enough spring (especially "over the nose pressure") to do the job,and to break in with weaker springs if the cam and spring specs are serious. I have measured cams that have little or no taper on the lobes front to back. That's poor grinding work and I don't run them. I like to see .0015-.002" taper across the lobes. I do regrind all my lifters to .0015-.002" taper/crown per inch of diameter. Lifters out of the box can vary a LOT. I haven't grooved the bores or ground flats on the lifter flanks yet...but the flats do make sense to me. I do believe in high quality cam lube and prefer Isky Rev-Lube. It's Molybdenum Disulfide based and really sticks well. Prelube the engine and set the fuel and electrical system up so the engine fires on the first revolution. Fill the carb float bowl through the vent tubes or use a small electric pump. Make damn sure the distributor is in correctly and firing order is right. When it fires I immediately speed it up to 1500 or so (I don't think 2000 is necessary-LOTS of oil flinging around in there at 1500!) and twist the distributor around 'til it has enough advance to run quiet and freely. Extra advance does no harm at no-load. I have the cooling system hooked up and a big fan running. No problem shutting down in case of a leak or getting too warm-just fix it or let it cool and restart. I'll run it 20-30 minutes total in one to three sessions. If all is well it goes in the car where it can get load applied right away. That's my way, and it's worked so far.
Another good tip is use the right ***embly depending on long it will set before firing up. Liquid lubes will be in the oil pan in a day or so, where as a grease type will still be in place weeks or months later. During break-in, keep it cool, keep it running, and keep it quiet so you can hear the engine, not the exhaust.
So does this mean the high volume oil pump I put in my 350 Chevy motor 30 years ago was a smart move?
Has any one experiment with Direct port oiling @ the cam lobe & lifter face , with injunction of typical oiling ? Nozzles direct @ as cam lobe turns into lifter ,, not a hole in lifter face. I recently seen a in house video Top tear race team , development and research That I was surprised shown to the public of a engine @ 9,500 rpms of the Valve train They slowed the frame's down so slow It was so slow it took 20 or 30 sec for One revolution from hill to max lift Seeing spring , rocker , push rod exc . They could rotate camera & Zoom in On what ever part they desire to look at.. The Technology is out there I'm wondering if Cam companies are doing this to see whats going on with cam to lifter face Contact, I have see also with sensors they can measure & get force / pressure bearing to crank rods & main's
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