Hi David
You had better start designing valve springs for the all the cam manufactures around the world because they must be getting it all wrong, it stands to reason that the bigger the cam the heavier the spring you have to run try telling some of the drag guys their springs are to heavy 400 to600 lb on the seat 1100 to 1500 lb over the nose, nascars running 2.1 to 2.2 rocker ratios with 1ins of lift up to 400lb on the seat around 800 over the nose .
Please don't compare a modern car or bike engine with over head cam and very light valve gear, and have a look at the after market cams for these engines that come with heavier springs, i have a honda cbr 2500rr that reves to 23,000 rpm and its standard, but with valve heads as big as a 5cent piece and 2mm stems they they dont need very heavy springs,
But one thing for sure i think there is a big difference between a marine engine doing 400rpm and a mini 8000 rpm.
Graham Russell

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

Pass some of that down here!



Can't believe I only just saw this! Great looking crank cometcosmo2003, can't wait till Swift have release more info on them (not that I own a car that would "actually" need one... still interesting though)




I'd have to agree.

Graham, I read your reply to this, and the post this quote was taken from....

I'm just rumaging through a mound of books and articles trying to find more info on the EN40B cranks as this is the second time this has come up recently.

I would have to agree with who ever it was you spoke to about nitriding EN40B to 0.060". It does sound rather extrordinary. Even during the 60's and 70's most cranks were only ever nitrided to 0.010-0.012" (hence most technical manuals suggesting you re-nitride after every grind). With EN40B, getting 0.020" penetration is an effort and expensive.
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When torsion occurs, the effect is greater felt at the surface than at the core. Its a twisting action.
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Typically nitriding is carried out to increase corrsion resistance, but more commonly wear resistance. Nitrided surfaces can range from 68HRc to as hard as 102HRc. There are places in the states that can apparently even get 1500HV (about 128HRc)
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Now if you had an item, such as a crankshaft and it had even a 68HRc (the low end of the scale) skin at 0.060" deep, it would yes increase its static ""stiffeness"", but as soon as it was subject to any kind of torsion,, I'd be concerned about an increased risk of cracking.

Nitriding hardens surfaces, yes, but it does also make them brittle (especially if it was at the harder end of that scale).

For every one reading this at home, to put how brittle a 68HRc work piece is into perspective..... ever droped a good file? They're usually around about 67-71 HRc... They usually snap just from being dropped (good ones anyway).. Thats why you're always told "don't use files as levers!!"

The effects of Torsion, are most dramatic at the surface, so if you had a Brittle surface and you twist it.... well, go stick a file in a vice and grab it with a pair of mulitgrips and twist it hard,, see what happens

This nitriding depth on S cranks has been debated for years, rumour has it that Rolls Royce did the heat treatment.
I have an EN40B S crank that went into my 1360 after regrinding to -.020"/-.020".
After a few laps of Wakefield Pk (motor had 1000 miles up) with the factory recommended .003" crank end float, it trashed the thrust washers, and the centre main bearing almost spun in the housing.
I took the crank back to Spiro at St George Cranks. He reground the mains to -.030" size. He commented that it was still nitrided, and still as hard as hell. So there ya go- my 2c worth.

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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.

I have it here, read on.....

So, who is right here????



And from BMC themselves




FYI, nitriding to 0.060" depth is impossible



OK.....OK......maybe then you got you decimal point in the wrong place.....

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Hold that thought....




Good to know Doc.



Now, I didn't say its impossible, i said getting 0.020" was an effort and expensive.

For most places to reach 0.020" they need to do it in a few hits. And its dear....

IF you can get it to 0.060", I don't think it would be commercially viable on a mass production item considering that the car was worth under $5000 brand new.

Perhaps that .060" is on grinding DIAMETER, not depth? .060" depth seems a lot, .030" is more possible.

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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.

At a strech, if it is needed, yes, but not really recommended for short cranks, like Mini ones.

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Hmmm - just thinking out loud: would a dual-mass flywheel help the situation?

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

Hmmmmm, this has been an interesting discussion but I don't think the flywheel is the answer

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Too many cars, and too little time.

GR,
re these 8 counterweight race cranks that you get made- no doubt they should run smoother, but has anybody cracked or broken one yet?

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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.

valve spring at 7000rpms-->

http://www.youtube.com/watch?v=i_NpzU4pGjc

& that`s a good one

just imagine what they`re doin at 12,000rpms

the cranks we had tested for hardening depth years ago (my dad did this when i was a kid) & worked with "Heat-treatment" up here in Brisbane --> the hardening would go about 15-18thou deep, & also found it to be very uneven through the crank,,, but if we left the crank in the center of the tank, for the whole weekend, the depth increased to 25-30thou & was more even thickness right through the crank

I`m sorry that i`m not right up with all the metalurgy, i was asleep through that class however i was always good at "testing" cranks & none of ours has broken so far (touch my woody)

there have been (However) a few that i`ve seen & heard broken from other people NOT taking my dads advice on the correct treatment or correct process tho,,, they thought they knew better &/or they were just stingeytightarsdbstards,

i won`t name names but there was this one guy up here in Brisbane who continued to diss-agree with my dads suggestions & continuously broke cranks,,, it`s been a joke around our own little scene for quite a lot of years,,, his engines never seem to rev freely either,,, funny that

can i tell you a story???

i promise it won`t be 5 pages long

when i was a young fella, i`d rip down to Byron Bay surfing (nothing`s changed there) & a mate of mine (Troy Story) had an old ex-army EJ holden Ute & we`d hop in that thing & fang it everywhere, but,,, we`d pin it hard as we could all the way to Lennox Head (when the surf was good at Lennox obviously) & it would crunch gears in every gear, it would leak oil everywhere, fume like a smelter, it was just crap, the whole car was just stuffed , but it just kept running

However,,, what surprised me the most was---> (now read this the right way if you may) that it would struggle (like any engine does) at valve float point,,, then struggle & complain at valve bounce (like they all do) & while i was waiting for a valve head to pop off & smash the entire engine to bits (The noise was deafening & giving me goose bumps,,, i was always waiting for that inevitable long walk home),,,, i was cringing the whole time , but Troy would always say "Trust me" & kept his foot in,,,, well,,,, the thing would suddenly smooth up, quiet-en right up, & then "SING" & continue to rev to the moon, smooth as silk, quiet as a mouse,,, it was like Magic

it went past/through that valve bounce harmonic & proceed to accelerate up to the next harmonic zone (which happened to be about 8500-9000rpms

now this was an old 138 side-plate grey motor & i`m not kidding you, it went fast!!!!!!

now i would never suggest to anyone to fit softer springs than needed, because it`s simply asking for a catastrophic failure with regards to valves &/or springs breaking,,, but this car & it`s ability to rev past valve bounce (SSOOOOOOooooo Many times over a 10 year period) & it`s sweet smoothness after said harmonic,,, really woke me up & made me look harder at valves , valve springs & engine harmonics

Moral of the story,,,, you`ll never know if you never go

If any of you have felt what it`s actually like (if you dare & if you can find an engine that will be reliably able to spin past valve bounce & feel it for yourself),,, it`s truely an amazing thing

if we could all have engines that did that --> """""RELIABLY"""" then our race engines would be even faster for 2 reasons

one:--> the spring is soft so less work turning the donk---> sooooo many people actually do fit springs that are "WAY" to strong for the purpose, all they`re doing is slowing the engine down & wearing things out

& #two:--> engines would be able to rev much harder & spin up higher into the next harmonic Zone, which is just WAY WAY faster again than std issue

however,,, here is where the age old saying "Horses For Courses" comes into play yet again

If we "KNEW" that our valves & springs wouldn`t break & if we KNEW that the followers & cam lobes wouldn`t wear or break & if we KNEW that the harmonics wouldn`t damage anything,,, & if we KNEW that the valves were being controlled well during valve float & valve bounce,,,, then we`d all be doing it that way

the problem is ---> The Laws of Physics

as was said in Star-trek song,,, "There`s Klingons on the starbourd bow"
&
"You cannot change the Laws of Physics"

BUT!!!!!!!!!!!!!!!,,,, you can try to trick them into believing it`s possible

to quote Colin Chapman--> """Add less weight"""

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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.

this is a bit of an off-shoot from the age old Ducati Desmo system, but still very similar

http://www.youtube.com/watch?v=GXIdOTkJhEY&feature=related

i`m not sure of it`s reliability yet, but i`m sure more of these designs will be played with over the years

the only down-fall i can see with it`s operation is the weight of the valve train,,, if it`s reliable then i see no reason why it wouldn`t work well

anyone care to share their own views????

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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.

Hi there,

Has anyone tried "beehive" shaped valve springs on a mini?

The difference between these and standard springs is impressive.
Because each spring increases in diameter compared to the coil above the different natural frequencies help dampen the spring surge. They also use ovate wire ( cross-section like chicken egg ) which has a greater surface area and therefore greater strength than round wire of the same thickness.
They also allow for spring pressures at full lift to be reduced by around 10-20% without reducing safe engine speed.
And the on seat pressure decrease of 15-25% cutting parasitic loss to friction and valve seat wear.
Worth a closer look?

Cheers

Take a look at the Video link
http://www.youtube.com/watch?v=NskusJdk ... re=related

Very interesting. I think they may have used different cams. Notice on the first one (conventional springs) the base circle doesn't seem perfectly round as there is a slight secondary movement on the valve when it should be closed.

Hi there,

That second jump is the valve bouncing/floating all over the place out of control, and you can see all the vibrations from this reverberating through the whole valve train assembly.

Cheers