Ive always (tried to) use new , or otherwise good condition 2nd hand Cooper "S" ones on all my race motors & i`ve always been very happy with them,,, (until recently) having them balanced with the entire reciprictaing mass is VERY important tho
We fitted one of the Std "S" ones to our turbo twin cam moke, but it shat itself after the Qld mini Car club Christmas party last year
now that`s the very first one i`ve ever seen (or heard of) let go,,, however, we must all now realise that these things are verging on the possibility of being approx 40-ish years old,,, so don`t think the std "S" ones are un-breako,,,ok?
In saying all that tho,,, we did spin that donk to some stupid revs , & for quite some time too
MY own personal, (first ever) 1415cc stroker full race engine that i build when i was 16 years old was set up to run at 8000rpms & after setting up the f/d gear ratio to suit the track , we decided it was a little zippy cause we ended up pulling 8500rpms on our taco,,, so after a little chat with my dad about the (slight) over revving he suggested that we tall-up the f/d ratio to drop the revs for safety sake, (but i didn`t change it) & he (eventually) came to the track to watch (& of course he wanted a drive too) BUT!!!! after that he suggested it was running more like 9000rpms & the taco was out,,,
so we had it checked & he was wrong,,, when my taco was saying 8500rpms it was actually doing 9200rpms
Lots of tacos don`t read accurately so have yours checked if you have any doubts
this race donk had a 2-piece "S" pulley, 1415cc stroker, 60-80 cam, 520thou valve lift , with one of my own cyl head-jobs, Super big long 3-into-1 full race 9000rpms extractors on it & a 45mm weber withvery long inlet trackt & LOVELY Bell-mouth ram tubes etc etc etc... now this engine was re-built every year (approx 40-odd race meetings each year, with normally 3 races nearly every saturday night & quite a number of other race meetings thrown in on some sundays at places like Echo Valley etc as well,,, so, at the end of every season, it was usually a quick re-ring & bearing, clean up the valve seats & re-new a few gaskets-n-seals , whack it back together & fang the crap out of it for another year, again & again & again,, so this poor old race donk constantly saw 9000rpms , for about 9 years solid
The pulley off that engine is what we fitted onto the turbo twin cam moke,,, & it`s shat itself late last year
so it`s not just romac balancers that give-up from the over-rev problem,,, any of them can do it if taken past their recomended rev for any length of time
But the std (2-piece) "S" ones are damn hard to beat .
