So are they worth £175?

They have there advantages but really only in a racing sence, they reduce valve wear, but only really benifical at high RMP, I have 1.5 rockers but a soild set (Minispares Keith Dodd ones) and they work well on my setup.

Don't they open the valves wider - thus more airflow (like larger valves?high lift cam) but unlike a high lift cam, do so without the side loading on the valve stem and so less wear in the valve guide?

Allen

yesss, but good tuning is not that simple - I wish it was !

No, definitely not the case - the reverse in fact.
Hi lift rockers are going to increase the side loading, and therefore wear, quite dramatically.

My opinion: if you're looking for the last ounce of power on a race motor they may give you the edge, but if you expect to get reasonable mileage between rebuilds then don't do it!

High lift rockers do increase the side loading which is why the roller tip variety are better than the solid versions. They eliminate the sliding action of the rocker tip across the valve stem.

This has a secondary benefit. Modern oils have reduced quantities of the anti-scuff additive ZDDP. It was found to affect catalytic converters. This reduction is causing problems in older engines with solid tappets and sliding metal to metal surfaces. Motor manufacturers compensated for this by using roller followers and valve gear. There's not a lot we can do about the tappets but replacing sliding surfaces with rollers is a good thing generally.

Whether it's worth £175 is really up to you.

Another point worth considering is that the increased loadings also increase rocker shaft wear. My local Mini specialist reckons that wear is detectable and noise increases after around 15000 miles. Full roller rockers eliminate this wear too but cost an arm and a leg.

I am a Fan of roller rockers.

Another point to check is are your valve springs going to cope with the additioanl lift?

Neil

i have 1.5 roller rockers on an avonbar built engine , seems to go ok for a mini ! Found this on the net ,

The ultimate lightweight alloy valve gear, giving maximum efficiency, cutting down side loading on the valve stem, and reducing friction and wear while increasing rigidity. The 1.5 hi-lift keeps valves open approximately 20% more at any given point, although opening and closing periods remain the same.

best bet is probably look it up in dave vizards book on tuning the a series , often he tells you of any benifite/worth and resulting power increase etc