Nick Jones Posted March 24, 2013 Share Posted March 24, 2013 Anyone have the correct dimension for the cam-bearing bore in the block for the 6 cylinder engine? Alternatively the correct clearance between cam and journal...... I have the journal diameter figures and cams to measure, but none of my books shows the bore and the block I have clearly has problems..... :(ThanksNick Quote Link to comment Share on other sites More sharing options...
GT6 M Posted March 24, 2013 Share Posted March 24, 2013 this in the PI ,or the Vit Nick.Any time I bunged a cam in, there is very very little room .IE it wont wobble up n doon, when they are being fed in, so its gotta be a tight fit.!!some body will have an engine out and can give though!!M Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 24, 2013 Author Share Posted March 24, 2013 It's another block that was intended for the Vitesse but now looks destined for scrap :'(. Suffice to say one needs to be careful when picking machine shops for line boring to fit cam bearings!I've got at least 5 - 6 thou clearance (think it should be more like 1 - 2 thou) and that's measured with feeler gauges so hardly ideal methodology and reality is probably worse. In spite of this it is still very tight to turn when fully installed........ :(Nick Quote Link to comment Share on other sites More sharing options...
69vitesse Posted March 25, 2013 Share Posted March 25, 2013 This is all Gods way of telling you to give up on cam bearings... Quote Link to comment Share on other sites More sharing options...
GT6MK3 Posted March 25, 2013 Share Posted March 25, 2013 From my notes as provided by Kai at WBCQuote:Cam bearing bore size is 1.969" +/- 0.0005". Again, safe thing to do ishave the components in hand and work backwards to the ideal size. Camjournal diameter + bearing clearance + (2 * bearing shell thickness) =ideal cam bearing bore sizeGood luck,C. Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted March 25, 2013 Share Posted March 25, 2013 Nick_Jones wrote:I've got at least 5 - 6 thou clearance (think it should be more like 1 - 2 thou) and that's measured with feeler gauges so hardly ideal methodology and reality is probably worse. In spite of this it is still very tight to turn when fully installed..... It sounds like the machine shop didn't have a boring bar long enough to bore the cam gallery, so have tried to do it by boring the front journals from the front, and the rear journals from the rear. My machinist told me that he didn't have the equipment to bore the journals properly, and that trying to do it in two operations never worked. Because I'm not running stiff valve springs, I decided not to bother with bearings.I'd say that your machinists owe you a new block, or at least should offer to bore, deck and align hone another one for free. If you trust them, that is. Quote Link to comment Share on other sites More sharing options...
DJB_Harvey Posted March 25, 2013 Share Posted March 25, 2013 My machine shop in Derby can do them properly , they've done around 6/7 blocks for me now with no problems ... They normally do Aston Martin blocks which are a lot bigger / longer .They have all the correct boring bars . Quote Link to comment Share on other sites More sharing options...
Richard B Posted March 25, 2013 Share Posted March 25, 2013 Hi Dave, can you pm me or post me their details? What sort on price to the charge for this? Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 25, 2013 Author Share Posted March 25, 2013 2729 wrote:This is all Gods way of telling you to give up on cam bearings...It's bl**dy working too.... :(It is now proven to be the case that this shop does not have the right gear or apparently the skills....Nick Quote Link to comment Share on other sites More sharing options...
Steve P Posted March 25, 2013 Share Posted March 25, 2013 Nick,Sorry to hear there is no resolution to this,glad i didn`t go for bearings now,what are the shop saying?Steve P Quote Link to comment Share on other sites More sharing options...
69vitesse Posted March 25, 2013 Share Posted March 25, 2013 Nick_Jones wrote:It's bl**dy working too.... :(It is now proven to be the case that this shop does not have the right gear or apparently the skills....NickFWIW, back in the day when I had a Sprint and you could still buy them new, some people tried to recover the worn blocks where the jackshaft went. It was very hit and miss, even in a time of plentiful, well equipped and experienced engine shops. 99% of them shops and the knowledge has gone. I bought a new block.If the hole has any ovality, its very hard unless you are extremely skilled, to persuade the tool to bore true to the axis, it will always try to recentre itself in the off true centre worn bore. Just to compound the buggerance factor, the bore will still be sensibly true at the clutch end and non progressively wear to oval at the timing gear end.I would respect any fitter who can pull that trick off reliably now, considering how little meat he has to work with. Quote Link to comment Share on other sites More sharing options...
Martin M Posted March 25, 2013 Share Posted March 25, 2013 Hi Nick,my original Manual says:Bore in Block: 46,82 - 46,858 mmCam Journal: 46,741 - 46,745 mmClearance: 0,066 - 0,117 mmFor the inserting Spitfire MK3 bearings we bored exactly 50,00 mm.Sad to hear the story from the block / line boring.CheersMartin Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 25, 2013 Author Share Posted March 25, 2013 Thanks for the numbers Craig & Martin :) Works out at approx 0.0026 - 0.0046". I'm comfortably over the top end of that.Thanks to all for moral support! The perpetrator is maintaining a tactical silence at this point - which will not be allowed to continue beyond tomorrow.CheersNick Quote Link to comment Share on other sites More sharing options...
TRTOM2498 Posted March 25, 2013 Share Posted March 25, 2013 The company that Mr Harvey mentions did my TR6 block. Several track days later, with regular bursts to 6500RPM + and all is well.I can thoroughly recommend them.Cheers. Quote Link to comment Share on other sites More sharing options...
69vitesse Posted March 25, 2013 Share Posted March 25, 2013 FWIW, how much does this cam bearing malarky cost? Quote Link to comment Share on other sites More sharing options...
TRTOM2498 Posted March 26, 2013 Share Posted March 26, 2013 Circa £150.00GBP. Quote Link to comment Share on other sites More sharing options...
69vitesse Posted March 26, 2013 Share Posted March 26, 2013 Looks in corner of garage at two spare low miles blocks.... Quote Link to comment Share on other sites More sharing options...
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