Valve bounce
Turbo Mini Forums

On 24th Sep, 2009 minimadmotorman said:
Cheers fella.

Not that am interested in building a short stroke turbo screamer or anything

Yes i moved to the darkside

Instagram @jdm_brett

Thats well interesting, thanks for that.

Thats saying the standard fitted height for valve spring is 35.3mm. But at 10mm of valve lift the 200lbs iskys only exert 180lbs of pressure.

If you shim them by 1.8mm then at 10mm lift you'll exert 200-210lbs.


I've measured the fitted height, all be it crudely with a tapemeasure.. but i measured 37.5mm so they're clearly set way too tall, even taking into account the inaccuracy of a tape measure lol

I guess i'll try that then, if anyone knows figures for the 330lbs isky springs i'd be greatful, so i can load them up correctly. Also, come to think of it, what sort of lbs should i be loading them up to at maxium lift?

Ta, Dan

valve bounce or valve float?

AlexF

with the springs slack i imagine it must be valve float?

Hi guys, its been a while. Winters over, and i want my beasty back :)

To recap...

Isky say their springs fitted on a sprite need to be 30.25mm heigh
Des says 33.5mm
And mine are fitted at 37.5mm

So eer... 4-7mm spacer.. this is a problem. I think this will have the springs sitting well out of their perch.

Any ideas on a solution? cut the collet groove further down the valve? can you do that? or some kind of spacer/bucket affair to rais the spring and keep it in place?

Has this happened to anyone else before?!

Answers on a postcard...


Dan

are you using the correct top caps?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

The Isky springs on my Rover 'Works' head have a spacer under the springs.

If thats any help?

If you were able to "rev through" the "valve bounce" it wasn,t valve bounce.
The engine will just stop pulling as soon as the valves start to bounce and virtually give up when they start to float a few milliseconds later.

Im still going for Sticky guides Dan!

Yep, got Ti top caps.

Yea sproket, Des Hamil says you need a 2mm spacer under the isky springs, problem is that if I did that they would still be 2mm under the correct fitted height. Its all very weird.

You can come round an give then a good reem when you're not busy Oli, i know how much you love that shiz.


Broke the block down today, my cam's fooked, whether its a result of stupidly trying to drive through the valve bounce :$ or the cause of the whole problem I don't know. But two of the lobes for intake 1+2 are messed up, just before the peak they've flattened off a bit, consequently the top of the peaks are sharper than they ought to be. :(

Balls.