Roller lifters on a Rover?
Moderator: phpBB2 - Administrators
- HairbearTE
- Guru
- Posts: 870
- Joined: Sat Nov 18, 2006 12:27 am
- Location: Melton Mowbray
The ramp angle on a roller is physically much steeper than on a flat tappet cam and only very high spring pressure can keep the lifter on the cam lobe. This itself is only possible due to a reduction in friction with the roller wheel arrangement. Interestingly if you lay a roller cam down side by side with a flat tappet cam of the same spec the lobes of the roller look much "fatter" in comparison. They are physically much fatter but the geometry of the roller lifter arrangement means that the actual difference in figures is not as big as you would think looking at the cams. The roller lifter experiences much greater side loads that the flat tappet design and the smaller the wheel in the lifter the worse the problem gets.
Which is the whole advantage of the roller cam!!!HairbearTE wrote:The ramp angle on a roller is physically much steeper than on a flat tappet cam and only very high spring pressure can keep the lifter on the cam lobe. This itself is only possible due to a reduction in friction with the roller wheel arrangement. Interestingly if you lay a roller cam down side by side with a flat tappet cam of the same spec the lobes of the roller look much "fatter" in comparison. They are physically much fatter but the geometry of the roller lifter arrangement means that the actual difference in figures is not as big as you would think looking at the cams. The roller lifter experiences much greater side loads that the flat tappet design and the smaller the wheel in the lifter the worse the problem gets.
I wonder why they haven't developed one for a DOHC engine? It is definately possible as I did a project on it once and developed a design that would work. Would need much taller cylinder heads though. Seems like current designs are going the way of follower valves though....
Zander
- HairbearTE
- Guru
- Posts: 870
- Joined: Sat Nov 18, 2006 12:27 am
- Location: Melton Mowbray
I would say that the reason rollers haven't been used in DOHC engine is probably because the whole developement of the roller cam came about as a result of the need to get more valve "curtain area" open time per cycle in engines that are hampered by 2valve design and/or bad heads - i'e. old V8's. A modern 16v DOHC design has as much valve as it needs. That is my assumption.crayefish wrote:Which is the whole advantage of the roller cam!!!HairbearTE wrote:The ramp angle on a roller is physically much steeper than on a flat tappet cam and only very high spring pressure can keep the lifter on the cam lobe. This itself is only possible due to a reduction in friction with the roller wheel arrangement. Interestingly if you lay a roller cam down side by side with a flat tappet cam of the same spec the lobes of the roller look much "fatter" in comparison. They are physically much fatter but the geometry of the roller lifter arrangement means that the actual difference in figures is not as big as you would think looking at the cams. The roller lifter experiences much greater side loads that the flat tappet design and the smaller the wheel in the lifter the worse the problem gets.
I wonder why they haven't developed one for a DOHC engine? It is definately possible as I did a project on it once and developed a design that would work. Would need much taller cylinder heads though. Seems like current designs are going the way of follower valves though....
Re: Roller lifters on a Rover?
Interesting Discussion. I have seen these and thought I would add it to see what you all thought.
Set of Roller Lifers for Rover V8 by Crower
https://www.crower.com/lifters/lifters- ... -body.html
Set of Roller Lifers for Rover V8 by Crower
https://www.crower.com/lifters/lifters- ... -body.html
Re: Roller lifters on a Rover?
They look very like mine,
I got mine from Triumphroverspares in Australia
I got mine from Triumphroverspares in Australia