WBXmayo

[937carrera]

Interesting. If you tweak the adjustment on the spreadsheet you'll be able to see that the cam profiles line up pretty well. Do you think that there's really 0.5mm of wear on the used cam, that seems a lot, but I don't really know what to expect.

FRom this data it looks like the adjustement might need to be around 18 degrees, but as you've done the spreadsheet now you can just mess with it until you get the best fit. Desktop engineering ... or in old language, measure twice (at least), cut once.

I think you've done a great job setting up the tool to measure the cams. The more you take measurements, the easier I suppose it will come, but I know there'll be a lot of work in taking those 250 measurements eachtime. Now you have the profile, maybe just focus on the peak of each lobe for the alignment... and perhaps not assume that each lobe is exactly 90 degrees round from the previous cylinder in firing order

[itchyfeet]

Interesting. If you tweak the adjustment on the spreadsheet you'll be able to see that the cam profiles line up pretty well. Do you think that there's really 0.5mm of wear on the used cam, that seems a lot, but I don't really know what to expect.

FRom this data it looks like the adjustement might need to be around 18 degrees, but as you've done the spreadsheet now you can just mess with it until you get the best fit. Desktop engineering ... or in old language, measure twice (at least), cut once.

I think you've done a great job setting up the tool to measure the cams. The more you take measurements, the easier I suppose it will come, but I know there'll be a lot of work in taking those 250 measurements eachtime. Now you have the profile, maybe just focus on the peak of each lobe for the alignment... and perhaps not assume that each lobe is exactly 90 degrees round from the previous cylinder in firing order

yes definitely lots of wear on the peak.

Unfortunately I'm not a wiz on excel! I can change the angle that refers to the data but then I have to combine two sets of data and I don't know how to do that yet.

it's not 250 each time each cam lobe is about 30 ish measurements so just rechecking 1 inlet and exhaust is quite quick

I thought of just doing the peak but to be sure you want to see the whole graph, and I'm also checking that Newnam cam is actually the same, here is 1 tooth offset, getting close.

I think CJH's 1 tooth + Advance 4 degrees is going to be it, dunno why I didn't just try that first

DJ vs Newman 1 tooth adjust by Paul_Barr, on Flickr

[937carrera]

That's almost there, I think an additional degree or so and you'll have the cam profiles aligned. I'm focussing more on the profile as the cam opens rather than the peak. Now the data is that close it looks as though the old cam has worn more on the lobe as the valves close again. Again, I don't know if that's expected or not.

Unfortunately I'm not a wiz on excel! I can change the angle that refers to the data but then I have to combine two sets of data and I don't know how to do that yet.

I'm used to working with data. If you want to PM the spreadsheet over I would be happy to take a look at it for you. If you want to develop your own Excel skills that's equally fine too, this is stimulating stuff

[itchyfeet]

Thanks for the offer but I'm there with 1 tooth ( 14.4 crank degrees) and 4 degrees on the adapter, no surprises it's the same as CJH so they probably just ground it and didn't check the cam I gave them, I will ask when I'm sure I have cheked everything.

DJ Worn Vs Newman with 18.4 degrees adjust by Paul_Barr, on Flickr

now to do 3&4

[itchyfeet]

This is Cylinder 2 looks fine to me.

I used the same scale and measuring method then shifted the data 180 degrees

DJ Worn Vs Newman with 18.4 degrees adjust cylinder 2 by Paul_Barr, on Flickr

Right that's me done on this, time to move on.

[937carrera]

Yep, looks like you have done it. Cylinder 1 looks spot on and there isn't any differential wearing on the nose of the lobe.

Number 2 seems to have a bit more overlap with the peaks being a little closer together, don't you think ?

Of course there's the inevitable measuring error to think about, and I doubt that the difference is such that it would make anything but the most marginal difference to the running of the engine

[itchyfeet]

Just out of interest

Used DJ vs New DG cylinder 1 by Paul_Barr, on Flickr

[itchyfeet]

back in the warm and with a scale attached it's clear the cam gear mark is -270 degrees from TDC No 1 as I had assumed in my graph above, it had to be a round number and somebody will figure out why, it's not going to be a random point.

^^^that's not true, the confusion I have had is the zero on the graphs is not TDC on either stroke, it's simply the theoretical crossover of the inlet and exhaust.



The cam gear mark is TDC
P1090187 by Paul_Barr, on Flickr

this is TDC on compression stroke, you can see the cam gear mark is inline with the piston/tappet ( it's a flat engine, what we think of TDC marks on the pulley are 90 crank degrees out from the real TDC)

P1090188 by Paul_Barr, on Flickr

this is zero on the graph

P1090189 by Paul_Barr, on Flickr

[itchyfeet]

New reference hole drilled

P1090193 by Paul_Barr, on Flickr

hole slotted as the Vanistan cam adapter has symmetrical hole pattern to allow you to adjust it and the origional gears have one hole offset so they could not be assembled wrong in the factory

P1090195 by Paul_Barr, on Flickr

ready to bolt up but I have had to order a 3/16" af hex to socket for use with a torque wrench.

P1090199 by Paul_Barr, on Flickr

[CJH]

Have you torqued up the M6x16 button head bolts that secure the ring gear to the vernier adapter? I found I wasn't able to get the required torque without the sockets rounding off. I found it odd that nobody else had had this problem, but it persisted with a different torque wrench, a different hex bit and a new set of cap head bolts. It was suggested to me that I should grind the tip of the hex bit flat, so that it didn't ride up out of the socket. I didn't do that, but I replaced the supplied button head bolts with M6x14 cap heads, which have a bigger (5mm versus 4mm) and deeper socket, so they took the torque easily. The extra height of the cap heads wasn't a problem, and being only 14mm long meant I could do away with the washers, which are only there to limit to protrusion of the threads.

[CJH]

Just out of interest

Used DJ vs New DG cylinder 1 by Paul_Barr, on Flickr

I think Silverbullet said in a different thread that the DG doesn't like the DJ cam - there's a small difference in the timing and a quite a surprising difference in the lift. I think this is a case where the area under the curve is significant - i.e. it relates to the total volume of gas (inlet or exhaust) that the valve allows to pass. I don't know what it is about the DJ profile that the DG doesn't like - too 'wild' for the shorter stroke engine somehow.

I plotted my Silverbullet(Holman) cam against my worn DJ cam, and was simply happy that the volume under the curve was greater, meaning that the volume of inlet and exhaust gasses is at least as good as the original DJ, but I think the difference is probably fairly insignificant.

[itchyfeet]

Have you torqued up the M6x16 button head bolts that secure the ring gear to the vernier adapter? ]

Not yet, still deciding if I'm going to use just thread lock or peen threads over also, worried about bending stuff if I peen threads.

I remember you saying this about the supplied screws, I wonder if the threadlock acts as a lubricant and to get the torque you need to tighten very much more.

I will do a test on the button heads but I ordered some cap heads too.

[CJH]

I remember you saying this about the supplied screws, I wonder if the threadlock acts as a lubricant and to get the torque you need to tighten very much more.

That's possible. If the threadlock acts as a lubricant and allows the same clamping force to be achieved with lower torque, that would help, but I'm not sure how you'd check that. But it's the torque applied by the 4mm hex bit to the bolt socket that I found to be the limiting factor, so with dry bolts or lubricated bolts, applying that torque caused the bolt sockets to round off.

[itchyfeet]

Agreed, you can just do 10Nm dry and even that is causing some damage to the 4mm hex, spec is 16-19 Nm.

Cap heads definately needed.

[itchyfeet]

Agreed, you can just do 10Nm dry and even that is causing some damage to the 4mm hex, spec is 16-19 Nm.

Cap heads definately needed.

It appears I'm wrong, I asked Chris of Vanistan and he says it's definitely possible and to go higher too, it's down to the end of the allen being rounded so it does not sit down fully, I will try again.