wow just wow, you gave a spot on informative training session, and I think you for teaching me the difference between roller and flat tappet cams & lifters.
Actually when you take into consideration that the flat tappet cam lobe sweeps across the bottom of the lifter from one edge to the other you will find that the flat tappet has a valve lift profile (area under the curve) very similar to the roller, the roller doesn't really pay big dividends till it starts jacking the valves open well past .500 lift, territory the flattie can't easily go to. A flat tappet can achieve higher off the seat acceleration rates as well. Where the roller really has it over a flattie is in the .200 + lift range as that's where it can steadily make more duration.
@Anu'schannel no flat tappets even though can achieve beyond if you made them wider so the lobe doesn't catch the faces, the pressures from the spring tension / acceleration angles would create wear. The video is not wrong at all, but I concur just as the person your replying to as this video . The Video is basic but not technical/ informed as it could be . It is geared to basic knowledge.. Also does not take into account a lot of factors that are lost with a roller. As its shape can take from with said radius. Now to simply answer your question from a summit catalog standpoint the roller is better and his explanation is explaining the tip of the iceberg to a deeper world. Area under the curve was mentioned, but so is acceleration angles and where the lobe may meet the face. A typical aggressive street roller would need a 1.2 " diameter flat face to handle the ramps and lobes of a roller lobe (and still limited to a point ) Nobody can bore over 1 1/4 lifter bores into a v8 block. And then may need a greater cam bore diameter to grind a unit to use it
Yes those and shorter pushrods because roller lifters are longer. Also the new roller lifters will need saddles to make sure they don’t rotate on the cam sideways.
For my 86 IROC Z (Flat Tappet) should I add a Zinc Additive to my oil to prevent damage to the cam and Lifter? TO my knowledge, Roller Lifters were not used on the IROC until 87 and beyond.
One can run solid roller lifters on a flat tappet mechanical cam if valve spring pressure is not over around 300 pounds and cam button is used. This is opposite of what everyone tells you but we had engine come into our shop this way that ran for years I am told and we tried it on 1969 z28 engine after it took out three sets flat tappet lifters and it liked the solid roller link bar lifters on the flat tappet E904P elgin cam
I need 8 tappets for a 30 yo diesel engine (Westerbeke) but none can be found. Are there businesses that could/would make them for a relatively reasonable cost?
This is gonna sound stupid but are rollers only for pushrod engines or is it universal where you could put roller cams on a sohc or dohc engine as well?
Roller lifter is the only to go. Since the 1980's 100% of all production cars are roller lifter. There is also a major problem with the EPA, at some point in time ZDDP will go to zero and thats the way it is.
If the fattie was actually flat ya but the contact patch on the roller is locked in the position of the lifter centerline so effectively the area under the curve (valve off the seat time) would be reduced compared to the original lifter.
