Hi All

This is what you call a really big camshaft, it's out of a top fuel dragster producing around 8000hp on nitro, it has .500tho on the lobe and uses 2.2 rocker ratio which give it 1.100" lift at the valve





Graham Russell

_________________
"It's better to be not informed than ill-informed"

Cool , can you grind me one like that for the sports850


Those things never cease to amaze me , I remember reading magazines in the late 70's where they thought they had pretty much reached the peak performance of the engine at 1500 hp , 8000 is almost unbelievable . The stresses involved must be phenominal .

_________________

that big mongrel gives me a big mongrel

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Thats what the RE83 is modeled on rite

_________________
Stop Licking the Dog...I Don't Care Who Started It

Well if thats true just how many ppm does he have to get to before it comes on cam



.

_________________

Can anyone say "duration" and "overlap"

_________________
Simon

The adventures of an owner builder in the Tallarook Ranges

Bear in mind these cams use roller followers, so the cam profile is pretty much just 2 radii blending into each other.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

What overlap ......the valves dont have time to be closed

Might fit something like that to one of the 998's i have lying around here just for a bit of fun, the std rockers will take it

_________________
http://www.youtube.com/watch?v=nDMkVq1jRGU

Hi Simon
to get that to work you need a cam follower about 1.5 ins in dia
other wise it would just sheer it straight off on the first rotation
like doc said it was ment for a roller follower.
But i'm working on profiles something like that, but i've had a
few little problems, but i'm working on that i'll get it to work
i won't give up that easily.
The RE83 is a long thoes lines thats why it needs good valve
springs, and thats part of the problem with the bigger cams
getting the springs to keep the follower on the lobe.
That dragster cam runs close to 750lb on the seat and 1500lb
over the nose
Graham Russell

_________________
"It's better to be not informed than ill-informed"

So who's the first to develop roller followers for the A-series?

_________________
No speakers, no bodykits, no six-inch spacers, no spak filler, no bullshit

Been done years ago by a few racers, but do you want to lose power or make it??
Not enough room in there to do it properly.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

any more info on the roller lifters?

i'm currently looking into converting a block to take some.

HI Mini13
Save your money a lot of work for no real gain,you can not
get the roller big enough on the lifter so your acceleration rate
is slower than a good flat tappet cam.
The back to back testing we've done on B series motors and
the big 6 cly healies proved it is not worth the effort
Graham Russell

_________________
"It's better to be not informed than ill-informed"

I believe a person in QLD has tried a roller cam in group N but havent seen any QLD times quicker than Greig.

Is it also, that to have a heavier roller lifter, with an already struggling valve spring trying to control a now faster lift cam, the problem? There is always a trade off.

Grahams blue springs are the best (heaviest) springs that have been made for the A series and to add more weight(lifter) and faster lift would mean it would float at a lot lower revs.

Graham, someone told me if you work out the working life of the nitro engines its something like 1000 revolutions. --6 sec pass @ 10k/rpm then it gets rebuilt.

Ben.

ps. Graham, i only rev it to 7000...honest.

Thanks Graham, that's interesting

What would you deem as a roller large enough? I am looking at followers from an american ford V engine.

What kind of back to back test did you perform on the B series?

Have you been unable to lift the valves faster than with an .87 is diameter flat follower? if so what was limiting the acceleration? side loadings into the block from the roller follower?

sorry for all the questions,