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Holden six cam database

Started by _oldjohnno_ , Aug 23 2013 10:47 AM

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49 replies to this topic

#1 _oldjohnno_

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Posted 23 August 2013 - 10:47 AM

Some of us here would like a bit more information on the available Holden six cams than the usual 0.050" and 0.2" numbers. And most of us with an interest in the little sixes would also have a cam or two in the shed - and what I'm talking about here is solid flat tappet or roller cams; I don't think there's any real interest in hydraulics.

So here's the deal: you grab the cam(s) you have, and note the tappet lift at 10 degree intervals. Ideally you'd zero the degree wheel at the lift equal to lash divided by the rocker ratio. For example if the cam runs 0.015" valve lash, you'd zero the wheel at 0.010" tappet lift. You then email the numbers to me at [email protected] or PM me here, and include the recommended lash setting for the cam. Also include the brand and cam or lobe numbers. I'll sort the numbers out into tables or graphs so it's easy to compare the different lobes. These will be published on a web page - I'll put the address up here.

Edited by oldjohnno, 23 August 2013 - 10:52 AM.

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#2 orangeLJ

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Posted 23 August 2013 - 01:18 PM

Whats the easiest way to setup a rig to test this? (so I can do multiples easily)

Ive got about 5 cams in the cupboard I could use

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#3 _oldjohnno_

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Posted 23 August 2013 - 03:32 PM

Whats the easiest way to setup a rig to test this? (so I can do multiples easily)

Ive got about 5 cams in the cupboard I could use

One way would be to get an old cam gear and hone out the bore with a flap wheel so that you can get it on and off the shaft fairly easily by hand. Attach the degree wheel to the gear making sure it's accurately centred (bad data is worse than none at all). If you do this you won't need a crank installed but you'll have to measure every 5 degrees rather than every 10 (crank) degrees. Remember there's no need to worry about where TDC is in relation to the cam.

Make a dummy pushrod about 5" long from solid rod. It'll need to be big enough to be a good fit thru the deck hole but not too snug. Face the top end off square so you have a good face for the dial indicator. Turn the other end down so it fits into the top of the lifter (or just epoxy a 5/16" ball to the end). Don't use any oil or grease on anything, just a spray of WD on the lifter to ensure rides consistently on the lobe under its own (and the pushrods) weight, and make sure the lifter falls freely in the bore.

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#4 _Bomber Watson_

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Posted 23 August 2013 - 03:38 PM

Could you do it as described but with the cam bearing journals sitting in v blocks and the dial guage right on the lobe?

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#5 _oldjohnno_

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Posted 23 August 2013 - 04:13 PM

Not unless you had a pad on the bottom of the dial gauge that was the same diameter and radius as the lifter. As the contact point moves around it changes the lift curve.

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#6 _Bomber Watson_

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Posted 23 August 2013 - 04:51 PM

Good call.

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#7 _oldjohnno_

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Posted 24 August 2013 - 12:37 PM

If anyones thinking about contributing but doesn't have a lot of time to spend on it, just start measuring at any random point and note the dial readings at 5 degree (camshaft) intervals until you've gone right round. Even 10 degree intervals would be OK. Dont worry about zeroing the dial or allowing for lash, just let me know what the recommended lash setting is when you send the numbers.

So if you test at 5 degree steps all you need to send is the set of 72 dial readings, if you check at 10 degree increments you'll send 36 dial readings.

Edited by oldjohnno, 24 August 2013 - 12:41 PM.

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#8 _oldjohnno_

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Posted 19 September 2013 - 08:53 PM

Here are a couple of mild ones to start off with. The first one is a Comp 6057, advertised 281, 244@50. Gross lift is.555". The curve below shows actual valve lift with lash and rocker ratio taken into account. Pretty high acceleration rate and lift for a street/strip cam. There is a bit of a kink in the curve on the opening side around .3 lift - I think this is just a glitch in Excels smoothing routine, the actual lobe doesn't look like that.

Next is a factory EFI cam. These have a reputation for being a very good cam for a hot streeter when the centreline is advanced, and I was quite surprised by how quick the opening acceleration was. Note though that the lift scales for both of these curves are different, so even though this curve looks as steep as the Comp one, the acceleration rate of the comp is quite a bit higher.

If anyone wants a copy of the spreadsheet to enter their own data it's here: http://oldjohnno.id.au/CamSheet.xlsx

A bit later I'll add a more to it eg. multiple curves overlaid on a single chart, and acceleration rates. Anyway, show us your cams so we can all see what good and what isn't. I'll measure some more up soon.

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#9 _oldjohnno_

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Posted 19 September 2013 - 09:12 PM

PS. I scaled the height of the VK curve down a bit so its lift scale is equal with the other curve. That's why it looks a bit funny but at least the two curves are now directly comparable to each other. It'll look much better when we have multiple curves on each chart.

Notice that the VK cam is noticeably assymetrical, with a gentle closing ramp. I think it'd be quite a good cam for a street car if it had more lift.

Edited by oldjohnno, 19 September 2013 - 09:19 PM.

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#10 N/A-PWR

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Posted 19 September 2013 - 10:16 PM

Very Good Work oldjohnno,

I will take one of my old cams to work tonight and put in the lathe and dial it in there at every 72. Dave I

p.s. got a lathe here, just only thought of it now with how oldjohnno explained how to easily

Edited by TORYPOWER, 19 September 2013 - 10:24 PM.

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#11 _oldjohnno_

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Posted 20 September 2013 - 08:59 AM

Very Good Work oldjohnno,

I will take one of my old cams to work tonight and put in the lathe and dial it in there at every 72. Dave I

p.s. got a lathe here, just only thought of it now with how oldjohnno explained how to easily

I'd love to see some data on some old school cams if you have any Dave. Just remember if you check them in the lathe that you can't just run the dial indicator directly on the lobe. Maybe you could make a tappet holder that fits into the tool post?

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#12 N/A-PWR

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Posted 20 September 2013 - 09:49 AM

I'd love to see some data on some old school cams if you have any Dave. Just remember if you check them in the lathe that you can't just run the dial indicator directly on the lobe. Maybe you could make a tappet holder that fits into the tool post?

Morning oldjohnno,

Yes that's how you explained before using the lifter as I forgot to take one to work, so I will do now at home.

Thought that the lifter be on centre with the chuck in the tool post and touch the lobe and record on the N.C. ( numerical control ) readout,

but your idea with the lifter guide sounds better. Dave I

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#13 N/A-PWR

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Posted 20 September 2013 - 08:42 PM

No Data yet, but made the lifter guide bush with a bronze to lifter sliding fit, bit of WB40 and all good:-

Lifter Guide Bush.JPG 44.81K 3 downloads Lifter Guide Bush.JPG 81.95K 2 downloads

Now to make the Lathe tool post holder for the Lifter Guide Bush. Dave I

Edited by TORYPOWER, 20 September 2013 - 08:51 PM.

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#14 N/A-PWR

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Posted 21 September 2013 - 01:09 AM

OK, got the Chuck Dial sorted,

0 to 360 at 5º - 1 to 72 every 14mm around the 4 jaw chuck which was 1008mm and the over lap was 3 mm out:-

Chuck Dial.jpg 25.79K 1 downloads Chuck Dial 1.jpg 26.68K 1 downloads

Chuck Dial 2.jpg 20.96K 2 downloads Chuck Dial 3.jpg 35.74K 3 downloads

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#15 _Ned Loh_

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Posted 24 September 2013 - 08:36 AM

bad data is worse than none at all

I've measured this sort of thing before, but I've known my figures were a bit rubbery due to that way I was measuring. With this thread in mind, I've poked around and come up with this. Seems to be giving accuracy within a thou. Should be ok?

Edited by Ned Loh, 24 September 2013 - 08:37 AM.

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#16 _oldjohnno_

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Posted 24 September 2013 - 07:24 PM

Looks good to me Ned.

I've only just worked your name out - yeah I know, pretty sharp eh? All this time I thought your parents must have been a Chinese couple with a fascination for Aussie bushrangers...

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#17 _Bluejinx202_

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Posted 24 September 2013 - 07:54 PM

If you have piston above deck, just watch for a low spike in lift with the magnet base there.

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#18 _Ned Loh_

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Posted 25 September 2013 - 08:46 AM

If you have piston above deck, just watch for a low spike in lift with the magnet base there.

cheers, but check the pics, no gear on the cam so the pistons aren't moving as I turn the cam over.

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#19 _Ned Loh_

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Posted 25 September 2013 - 02:38 PM

Looks good to me Ned.

I've only just worked your name out - yeah I know, pretty sharp eh? All this time I thought your parents must have been a Chinese couple with a fascination for Aussie bushrangers...

Haha. Some people think I'm a bit of a bushranger at times, but at the end of the day I'm a holden man at heart.

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#20 _oldjohnno_

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Posted 26 September 2013 - 01:37 PM

There are a million ways to skin a cat. This one has a piece of old pushrod loctited into it - the length makes it easy to set up the dial and the weight helps keep the lifter firmly seated.

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#21 _oldjohnno_

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Posted 27 September 2013 - 06:30 PM

OK, here are four lobe curves on one chart, which makes it a lot easier to compare them. All the curves are net valve lift and account for lash and rocker ratio. All are 0.842" lobes. They are:

6301 - nominally [email protected]"

6231 - nom. [email protected]"

6241 - nom [email protected]"

VK EFI - about [email protected]"

Apart from the obvious huge difference between the EFI lobe and everything else (as expected) it's interesting to note the difference between the 6231 and 6341, even though both are 236@50. These are all pretty mild by modern standards; it'd be good to compare them to a more aggressive .903" cam and also some traditional style lobes. Also note that the lift of all these is below the limits of any half-decent head, so pretty much all of the area under the curves counts to some extent.

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#22 _oldjohnno_

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Posted 29 September 2013 - 09:35 PM

Here are some interesting ones. First, a Comp6057 and a CamTech 642A. These two curves have nearly identical areas under the curve and have very similar seat durations too. The only real difference is that the 6057 manages with exactly 10 degrees less duration at 0.050"

6057%20vs%20642A.png

Next is a Waggott (not sure of the part number) and a Comp 6231. These two were paired because of very similar 0.050" durations. You'll notice that the 6231 (one of Comps limited lift lobes) has a lot more area under the curve, and does it with less seat timing which would allow a lower static CR.

Now we have a COME 235 and a Comp 6231. These have almost identical seat timings and therefore would want similar CRs. The 6231 however has more duration at 0.050" and maybe 10% more area, and would be expected to be the better performer.

Finally, a blast from the past, an old Bert Jones grind compared to the Comp 6241. The Jones cam has slightly longer duration at 0.050" and sunstantially more at the seat. It'd need a fair bit more CR and has slightly less area (and therefore performance potential) than the 6241 despite the longer duration.

That'll do for now. Keep in mind that most of the modern stuff shown so far has been pretty conservative 0.842" stuff. Hopefully I can get some data on some more aggressive 0.903" lobes soon - I think the difference will be startling. Thanks to Warren and Ned for sharing some of their cams.

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#23 _oldjohnno_

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Posted 30 September 2013 - 07:36 PM

Tonight we have a Crow 35872 (thanks Ned!). It's shown with Comps 6231 and 6241 lift-rule lobes. Crow, CamTech and Tighe appear to use a lot of the same lobe masters and these seem better than those from some of the other Aussie suppliers. Anyhow, you can see from the curves that there isn't much at all between the three of them with nearly identical lift rates. The 6241 has a narrow (5% or so) lead over the others.

Just for interests sake here's the same Crow lobe with rocker ratios of 1.5, 1.6 and 1.7. As you can see the bigger ratios have a marked effect that increases proportionally with lift. I'm guessing that the 1.7 might give 10% or so more area than the 1.5.

Edited by oldjohnno, 30 September 2013 - 07:42 PM.

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#24 Dave6179

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Posted 01 October 2013 - 07:35 AM

When I was trying to fix, what I thought was a rocker/valve problem on my new 202, I swapped the 1.6 rollers for a set of 1.5 rollers. On the road the 1.5's felt a bit flat, like it was running out of puff. I was rather glad to put the 1.6's back on! Surprising the difference such a little change can make.