Tricky-Ricky Posted December 12, 2007 Share Posted December 12, 2007 Does anyone know what the base circle diameter of the st cam? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 12, 2007 Author Share Posted December 12, 2007 None of the tech oriented people know?? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 13, 2007 Author Share Posted December 13, 2007 Does nobody know? maybe Chris Wilson? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 13, 2007 Share Posted December 13, 2007 Without putting one on a cam measuring machine I could only approximate. If I could draw on screen I could explain why very easily, but I can't and to put it into words would take all day Quote Link to comment Share on other sites More sharing options...
dandan Posted December 13, 2007 Share Posted December 13, 2007 I could probably get the numbers for you by early next week - would need to bring one to work....why do you ask? (Basically are you just interested or is it important?? ) Quote Link to comment Share on other sites More sharing options...
Wez Posted December 13, 2007 Share Posted December 13, 2007 I have some stock cams in my loft, if you explain how and what to measure I can check them later Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 13, 2007 Author Share Posted December 13, 2007 Well like Chris says its really only going to be a rough measurement without the properer equipment, but i just wanted a reasonable approximation, I'll explain, i have bought a HKS 256 inlet cam, but on checking the overall hight i find that its pretty much the same as std hight, which worried me as it supposed to be 8.7mm lift and not 7.8mm which is std, suddenly remembered that if i got the base circle dia i could work out the lift, so i measured the BCD and yes i know it all depends on the amount of ramp the cam has, but after measuring i found that it did indeed work out to 8.7mm lift, and if that is the case, then the amount of shimming that will be needed will be more! (has anyone found this with HKS cams?) So its either that or this cam has had a regrind, which is my point for the question. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 13, 2007 Share Posted December 13, 2007 OK, HKS cams in that configuration do have the quoted lift, but they keep the tappet clearance part of the "base circle" very close to stock, to minimize shimming. I can measure the smallest OD of a lobe (inlet or exhaust?) as a comparison, but this may well not be what you consider the "base circle diameter" as it may not centreline on the true cam centreline As a comparison it should be fine though. It won't get done today, maybe tomorrow. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 13, 2007 Author Share Posted December 13, 2007 OK thanks Chris, that would help:) Inlet. Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 13, 2007 Share Posted December 13, 2007 I've got a set of stock cams that I can stick in a couple of V-blocks and measure the actual cam profiles using our laser scanner, and will be able to give you the exact dims. I'll have a quick go at it after work if the cams are still here (change them here at work and can't remember if I took them home or not). Quote Link to comment Share on other sites More sharing options...
Wez Posted December 13, 2007 Share Posted December 13, 2007 I've got a set of stock cams that I can stick in a couple of V-blocks and measure the actual cam profiles using our laser scanner, and will be able to give you the exact dims. I'll have a quick go at it after work if the cams are still here (change them here at work and can't remember if I took them home or not). Sounds cool Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 13, 2007 Author Share Posted December 13, 2007 Thanks guys:) anything will help. Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 13, 2007 Share Posted December 13, 2007 Here's the screen grabs of my J-spec 110Kmile old cam profiles:- The No.1 camshaft (IIRC that's the inlet) The base circle diameter is 35.419mm Here's the No.2 camshaft. The base circle diameter is 35.381mm If there is a particular dimension anyone wants me to measure then let me know. I've also attached the .catpart documents that anyone should be able to open in Catia V5 and also the IGES files, which should be able to be opened in most anything. One thing to be aware of though is that I used a 10mm dia probe when measuring these, so you should take that into account. (I could have offset the surfaces inwards by 5mm, but to be honest.... I forgot!) J-spec camshaft profiles.zip Quote Link to comment Share on other sites More sharing options...
Wez Posted December 13, 2007 Share Posted December 13, 2007 Nice work Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 14, 2007 Author Share Posted December 14, 2007 Thanks for that, but i did forget that i would also need an overall hight dimension from lobe to base dia please. Also just put a mike on mine again and got 36.068 converted from imperial, i know its possible may be getting a bit of the ramp in that measurement, but its interesting that if its right it would almost negate the extra lift of the cam. Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 14, 2007 Share Posted December 14, 2007 Ah be careful though. I don't think you can measure the base diameter with an internal micrometer as the base circle of the cam shaft isn't a full half circle, it's only actually radial for about 20 degrees at the bottom. I'll sort out what the lift is later today.... Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 14, 2007 Share Posted December 14, 2007 Ah be careful though. I don't think you can measure the base diameter with an internal micrometer as the base circle of the cam shaft isn't a full half circle, it's only actually radial for about 20 degrees at the bottom. I'll sort out what the lift is later today.... Exactly, that's what i was trying to get across, without measuring from the central axis of the cam, with (say) the journals in V blocks, or an a cam measuring fixture with 3 axis probe, you can't put a micrometer across the smallest OD and necessarily get the base circle diameter. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 14, 2007 Author Share Posted December 14, 2007 I did realise this, but like i said it all depends on how much of a ramp the cam uses and where it starts, i was hoping to get some Toyota figures, they give the overall hight in the manual but no BCD, but approximate is good. Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 14, 2007 Share Posted December 14, 2007 Well to within 10 microns, it's the valuse I mentioned above! Quote Link to comment Share on other sites More sharing options...
bromy Posted December 14, 2007 Share Posted December 14, 2007 I have access to a Mitutoyo CMM that would be able to measure the base circle accuratly to microns... but I dont have any cams Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 14, 2007 Author Share Posted December 14, 2007 Well to within 10 microns, it's the valuse I mentioned above! Tony, do you think you could give me the overall hight please? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 17, 2007 Author Share Posted December 17, 2007 Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 17, 2007 Share Posted December 17, 2007 Ah sorry mate. Had obviously forgotten about this. I'll try to remember to check it when I get home tonight. Quote Link to comment Share on other sites More sharing options...
TLicense Posted December 17, 2007 Share Posted December 17, 2007 OK for the no.1 camshaft the lobe to base circle centre is 26.36mm. This gives a total rise of 8.65mm. For the no.2 camshaft the lobe to base circle centre is 27.03mm. This gives a total rise of 9.34mm. Again this should be accurate to about 10 microns (0.01mm). Hope that helps! Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 18, 2007 Author Share Posted December 18, 2007 Thanks Tony:) just for reference, according to the manual the tolerance for the cams is intake - 44.570 - 44.670 exhaust - 44.770 - 44.870 the trouble is those figures for lift can't be right according to Toyota as they 7.8 mm for intake and i think 8.4 mm for exhaust, so I'm slightly more confused now:blink: Quote Link to comment Share on other sites More sharing options...
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