tiddy1 Posted February 24, 2003 Share Posted February 24, 2003 I am looking at fitting a 285H cam in my K-series and I am amazed to hear that at 11mm max lift the current springs will go coil bound, This is only a couple of mm over standard lift? Piper reccomend thier springs (obviously) as they say it is good for up to 13mm lift however it rediculously stiff. they quote 240LB which when you calculate the max decelleration of the valve (the determining point for the valve spring load) and the required valve closure force (about 55lb holding the valve closed) at a max of 8000 rpm you find that 140LB springs would be far more sensible. It seems to be a very common problem that the likes of piper and kent suggest far stronger springs than needed. So the questions are : 1. what is the standard spring load 2.Bo you really need different springs for 11mmm of lift 3 where can I get some 140LB springs that do not go coil bound Simon Link to comment Share on other sites More sharing options...
AMMO Posted February 24, 2003 Share Posted February 24, 2003 Simon I think the 240 lb figure is per inch, not over the nose pressure. Some stock Zetec springs also go coil bound if you go to 11 mm lift. The Zetec single springs are 140lb over the nose. AMMO Edited by - ammo on 24 Feb 2003 12:48:16 Link to comment Share on other sites More sharing options...
tom7 Posted February 24, 2003 Share Posted February 24, 2003 All the work on the original VHPD's etc for 8000+rpm was done using Land Rover TD5 valve springs. I Don't know what the ratings are, but these were the ones supplied to Minister, Janspeed et al in the first place. Tom Link to comment Share on other sites More sharing options...
Rob Walker Posted February 24, 2003 Share Posted February 24, 2003 Simon, I remember measuring the standard springs at Dave Andrews place. What you also have to bear in mind is that the springs are under 15mm of preload before the follower is depressed a further 11mm by the cam at full lift. The high rate springs are coarsley wound and having fewer turns with thicker wire gives you the extra clearance between the turns. I take your point about the poundage though, why use more than is absolutely necessary ??????????? Rob Edited by - Rob walker on 24 Feb 2003 16:48:10 Link to comment Share on other sites More sharing options...
tiddy1 Posted February 24, 2003 Author Share Posted February 24, 2003 So does this mean I need to change the spring caps as well so they do not bottom out? Link to comment Share on other sites More sharing options...
tiddy1 Posted February 24, 2003 Author Share Posted February 24, 2003 Rob I have just worked that out if you have 15mm pre-load on the springs then thats 140lb valve closing load!!!!! thats just rediculous, The F1 boys reckon 50Lb is as much as you would ever want, may be a deisel needs this load but a K series should not, It must make it very hard for the starter motor to turn the engine over!! Simon Link to comment Share on other sites More sharing options...
KenEvans Posted February 24, 2003 Share Posted February 24, 2003 Oilyhands should be along shortly. I bought my 285H cams via Oily and he provided the correct springs too. His advice is very dependable and accurate. Ken Link to comment Share on other sites More sharing options...
Rob Walker Posted February 24, 2003 Share Posted February 24, 2003 Simon, I am affraid I fitted them without really thinking about the poundages/load just hoping Piper knew its stuff. I have the double springs fitted and can confirm that its hard to even turn the cam pulleys with a spanner. I was also advised to fit the steel spring caps to be safe. Link to comment Share on other sites More sharing options...
oilyhands Posted February 24, 2003 Share Posted February 24, 2003 The Piper single springs arent ridiculously stiff.. the double ones are though. You dont need any special caps to utilise the Piper single springs and the BP285H cams lift about 2.5mm more than the stock ones, valve springs dont need to go coilbound to be unsuitable for a given lift, ideally there should be at least 20thou clearance between each coil for the spring to be safe, check a valve spring in a vice from an installed height of 37.2mm and see how much lift it will tolerate before closing to more than a 20thou clearance. If you subject a spring to more than its designed compression it will fatigue and break with the usual expected mayhem. The stock springs are 56lb as installed and 101lb at max lift. I dont know the over the nose pressure of the Piper springs but it will depend on installed height and maximum lift, the BP285H cams are not the only profile that the springs are designed to work with. A call to Warren at Piper would reveal the appropriate figures. Using some simple maths, if they are rated at 240lb/in and their free length is 43mm, then at 26.1mm (installed height of 37.2 less lift of 11.1) they would be near (240 /((43 - 26.1) / 25.4)) = 159lb and 54lb when closed. VVC springs will tolerate more lift than the stock items and are softer, they wont take 11.1mm though. Oily Edited by - oilyhands on 24 Feb 2003 23:35:06 Link to comment Share on other sites More sharing options...
KenEvans Posted February 24, 2003 Share Posted February 24, 2003 See? Where would we be without him? Link to comment Share on other sites More sharing options...
tiddy1 Posted February 25, 2003 Author Share Posted February 25, 2003 Thanks for all the advice looks like single uprated springs are the ones to go for. Just wanted to make sure Simon Link to comment Share on other sites More sharing options...
I.Mupferit Posted February 25, 2003 Share Posted February 25, 2003 Oily, Reading this has got me worried now, are my springs going to be ok with the BP285 cams, albeit on my Zetec? Brent 7 in bits, LOTS of bits ☹️ Link to comment Share on other sites More sharing options...
oilyhands Posted February 25, 2003 Share Posted February 25, 2003 Hi Brent, The BP285s you have are made to work with the stock Zetec springs. Do you remember how I remrked that the stock springs looked very similar to the K series and gave you a set of VVC springs? Well it turns out that the springs Piper supply for the K are identical to those they supply for the Zetec. I think you will be OK with the VVC springs since they have more clearance on the coils than the stock ones, if you are worried then I have a set of K/Zetec Piper springs here for £77 inc VAT. The installed height of the Zetec springs is about 1mm greater which gives sufficient coil clearance. Oily Link to comment Share on other sites More sharing options...
I.Mupferit Posted February 25, 2003 Share Posted February 25, 2003 Thanks Oily, that's put my mind at rest . I do remember your comments re the stock springs-v-the VVC springs and, indeed, have fitted these. I just get paranoid when I see threads such as these when I haven't yet got my engine running Brent 7 in bits, LOTS of bits ☹️ Link to comment Share on other sites More sharing options...
V7 SLR Posted February 25, 2003 Share Posted February 25, 2003 Bugger me but those double valve springs are hard to turn by hand with a spanner. I was worried that the cam belt wouldn't be strong enough to turn them but I needn't have worried. Although the cam belt is essentially nothing more than reinforced rubber, when I turned the crank by hand it required very much less force, thanks to the 2:1 gearing, than turning just the cams even tough I was now essentially turning both cams at the same time. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
oilyhands Posted February 25, 2003 Share Posted February 25, 2003 Nigel, Remember.. as one cam lobe is opening a valve and compressing a spring, another valve is closing and assisting your turning.... Oily Link to comment Share on other sites More sharing options...
V7 SLR Posted February 25, 2003 Share Posted February 25, 2003 Oh yes I know that, but even so, turning the cams by hand was not easy, yet thanks to the gearing of the crank:cams (I guess) it's a lot easier, and has eased my concerns. Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours Link to comment Share on other sites More sharing options...
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