10 replies to this topic

[neil_g]

came across this on another forum:

linky linky

basically what is said is that roller rockers promote excess wear on cam lobes, and that a company called AC Dodd agrees.

what do you lot reckon? true or false?

[siggy]

Adrian Dodd is aperson not a company is a very well respected Mini tuner, in the same league as Keith Calver. And as I have no proff otherwise I would agree with what he says.

Siggy

[Bluemini]

Roller 'tip' rockers, and 'full' roller rockers are designed to reduce wear, mainly side wear on the valves stems and guides because the rocker rolles over the top of the valve as it pushes it open instead of dragging over it pushing it sideways. I ran them for a while and they were a big improvement, not just on power but it felt alot smoother too.

[Pavel]

Rich you didn't cover the wear on the cam lobes... that may increase, I myself have no proof to show whether it does or not.

One thing you have to remember: ANY modification that increases power will increase wear. More power = Less engine life.

[Sutty01]

One thing you have to remember: ANY modification that increases power will increase wear. More power = Less engine life.

never know this and now im do im glad

IT MAKES SENCE

[bluebottle]

i've had 1.5:1 roller tip rockers fitted for about 20,000 miles now, in conjunction with a 276 cam, if as was said on the quote from the minifinity thread, they promote lobe wear, you'd be doing your tappets every few miles to compensate, i've just been checking mine every now and then, and just had the usual few thou of adjustment needed.
so i'd have to say, in my experience, they are no different to standard ones

a friend of mine has a 296 scatter cam and full roller rockers, this set up is about five years old, and still going strong in a hill climb mini, so i'll let you draw your own conclusions.

[Bluemini]

They wont make the lobe wear any greater than normal unless you are using heavier or double valve springs and I never had any problems. The spirngs are the main contributing factor to and force put on the cam lobes.

[bluebottle]

both engines mentioned above are running double springs.

[neil_g]

so basically there are alot of happy people running roller tips who haven't seen any noticable cam wear.

it may be possible with "heavier" valve springs due to the increased pressure, but again there are happy people running this too.

i think its also worth remembering that when modifying/tuning an engine the age and condition of said engine and component parts may determine subsequent wear, and that no two engines are the same.

or am i completely off the plot?

[Wil_h]

Because all roller tip rockers (that I know of) are 1.5:1 rather than 1.25:1 I think this will increase wear on the lobes.

As for the adjusting the tappets, the measurement is made with the valve closed and the cam lobe at it's minimum position. This part of the lobe will hardly wear at all. I guess the only way to check for wear is to measure the lift and compare that to the cam spec.

However, valve guide wear should be considerably reduced. Either way a few thou of wear of the cam isn't going to affect engine performance much. I guess if you wanted optimum BHP it would be a concern but for most of us what's 1 or 2 BHP?

I use roller tip rockers in my hillclimber and have had no problems.

Wil

[bluebottle]

silly me!....of course you do your tappts with your valves closed!.. :nugget: ....what can isay....it was early,the pope made me write it, it was my evil twin...it was the fenbillies.....