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xu-1 holden 6 camshafts

Started by _Ozzie Picker_ , Jun 12 2011 08:50 PM

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#26 _oldjohnno_

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Posted 02 May 2012 - 09:29 AM

A couple of further comments:

The old XU1s didn't even crack 1hp/cube. They did the job back in the day but today even grandpa's Camry makes a mockery of them.

Modern profiles in the little six aren't a new idea - I'm certain that the guys making good numbers in classes like NC have been using them for quite a while.

You can't just swap a "modern" profile for an antique one of the same duration, and if you do you'll almost certainly be disappointed. Adjustments to the LSA and seat-to-seat duration will have to be made to get the most from them.

If your cam grinder has nothing but a bunch of old-school masters hanging on the wall don't be surprised when he recommends an old-school cam. He can't sell what he ain't got...

Edited by oldjohnno, 02 May 2012 - 09:34 AM.

#27 _Ned Loh_

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Posted 02 May 2012 - 02:03 PM

This needs its own thread. Heads are still being developed (slowly and by few) but I think most of us would have the most to gain in this area.

My initial reaction was that we have enough trouble keeping the lobes on the last thing we need is a 'higher intensity' camshaft, but I think I was on the wrong tram as they wear over the nose and the 'modern cam intensity' would be in the ramp and flank.

Put me down for a comp if it happens.

#28 _PeteXU1_

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Posted 02 May 2012 - 02:17 PM

So basically the cam I have been running thus far could be classified as a "high intensity" camshaft. The crow 35647 has 290 advertised duration and 254 @ .50. An aggresive ramp I take it. Compared to say the 629B I will likely install, advertised duration is 322 and @ .50 is 266. A little basic maths would show there is 36 degrees of lift under .50 on the crow, and 56 degrees of lift under .50 on the 629B - and 12 degrees difference of @ .50 lift.

So can you make a "high intensity" version of the 629B by changing the initial ramp? Keep the @ .50 duration the same, but decrease advertised to say 310?

#29 _Ned Loh_

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Posted 02 May 2012 - 02:46 PM

Are both the advertised durations being measured the same way? (0.004, or 0.006, or 0.020, or ???)

Makes much of this sort of thing difficult.

#30 _PeteXU1_

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Posted 02 May 2012 - 02:53 PM

yes, my head hurts.

#31 _oldjohnno_

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Posted 02 May 2012 - 04:50 PM

Are both the advertised durations being measured the same way? (0.004, or 0.006, or 0.020, or ???)

Makes much of this sort of thing difficult.


It sure does. The only "advertised" figure that really has any relevance is one that corresponds with the actual lash setting. But unfortunately not everyone uses the same standard; for example the 629b that Pete mentioned had an advertised duration of 322, yet Camtech list it at 305 - for the same lobe. I think you need to have duration figures for actual lash as well as 0.050" and 0.2" at least to get any idea at all of what you're buying. It seems at least some of the US grinders fudge the figures a bit to make the "advertised" duration appear shorter.

#32 biga064

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Posted 02 May 2012 - 07:35 PM

I recently had an email discussion on this subject. I've pasted part of it below

Hi Old Johnno when might these cams be available ? will they be solid or hydraulic ? Whos making these modern designs I want one !!!!! thanks

Edited by biga064, 02 May 2012 - 07:38 PM.

#33 _oldjohnno_

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Posted 02 May 2012 - 07:47 PM

Don't get excited. My projects make glaciers look recklessly fast...

#34 2600s

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Posted 02 May 2012 - 07:57 PM

Hi guy's,

I am in the process of having my engine freshened up in my LC GTR and would like to pick a cam which sounds a little more lumpier than the standard LC GTR.
I don't want anything which will pig root and be hard to drive, although I want a cam which still performs well in a stock 2600s engine, any ideas??

#35 Litre8

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Posted 02 May 2012 - 08:16 PM

And I guess if you throw in a mechanical roller that would really wake up a 202 (with the appropriate head, induction and exhaust).

#36 greens nice

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Posted 02 May 2012 - 08:47 PM

I used a Cam from COMP in a 202 i recently built, a bit wilder than your average Holdon 6 Camshaft.
Performance Wholesale in QLD deal with them, give them lobe number's you want, separtion etc and 2 weeks later its in Australia.
I've been told that Comp have steel billet's to grind you a roller but they only list cast core's on they're site.
The Cam was 301/307 @ .020
272/276 @ .050.
180/184 @ .200
and .590" valve lift on 105 Center's.
Was advised to not add anymore ramp without regrinding lifter's otherwise it would be impossible to keep lobes on it.

#37 _oldjohnno_

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Posted 02 May 2012 - 09:31 PM

Happy with it Kevin?

#38 greens nice

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Posted 02 May 2012 - 09:42 PM

yes and no, it should be performing better but that is not the Camshaft's fault.
eng has a alloy YT head but the Weber manifold is for a 9 porter, the intake port roof is a good 10mm higher than the manifold, customer took her out for a blat with the 9 port mani anways. I dont like the extractors on it either.
still ran a 12.8 @ 104 first and only run off the trailer in a 2650 pound humpy. 1.75 60ft's as the front wheels are a metre in the air.
but there's still a heap of fiddling to do. :spoton:

Edited by greens nice, 02 May 2012 - 09:42 PM.

#39 _Inj gtr202_

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Posted 03 May 2012 - 12:19 AM

I can get my head around what most of the numbers quoted on a cam card mean and how they affect your motor.
But I can't work out what info you get from the Lift at T.D.C. I assumed it was just another point at which you can check your cam timing on installation.

Note: I went from an old school XU1 grind to a new camtech grind. The difference in power is pretty big without the loss of drivability.

Old Cam was a crow 304.
Adv dur. 304
.05" dur 226
In 43/81
Ex 83/41
Lift .423"
L/C 110

New Cam

Posted Image

#40 _oldjohnno_

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Posted 03 May 2012 - 07:15 AM

Lift at TDC is just another reference point that can give some indication of the lift under the curve. For example Comp quote lift at TDC at two different centrelines (106 and 110 from memory). So if one cam has 0.1" at TDC, and another has 0.12" it'll give some indication of the available flow during overlap.

I mentioned this before but I'll bring it up again: with these "aggressive" profiles it's easy to get stupidly high amounts of area under the curve during overlap. With durations longer than say 260@50 it can get ridiculous. To compensate you'd need to run LSA's that would be thought of as too wide (and durations too short) with traditional cams. Lots of rocker (say 1.7:1) may require more spread again. Where the old school stuff may have liked 105 you could well end up around 110 with the new profiles. And if you were to neglect this and just use the traditional values with an aggressive lobe I think you could easily end up with a dog.

#41 _Ned Loh_

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Posted 03 May 2012 - 08:11 AM

I can get my head around what most of the numbers quoted on a cam card mean and how they affect your motor.
But I can't work out what info you get from the Lift at T.D.C. I assumed it was just another point at which you can check your cam timing on installation.

Note: I went from an old school XU1 grind to a new camtech grind. The difference in power is pretty big without the loss of drivability.

Old Cam was a crow 304.
Adv dur. 304
.05" dur 226
In 43/81
Ex 83/41
Lift .423"
L/C 110

New Cam



Ok, so you have Camtech's advertised duration lift (0.020), but what is the crow? What about at other points?

Now saying that the crow isn't a dinosaur (it is), just that you need more info to make informed decisions. As I said above to PeteXU1 above - makes much of this sort of thing difficult.

#42 _Ned Loh_

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Posted 03 May 2012 - 08:14 AM

I used a Cam from COMP in a 202 i recently built, a bit wilder than your average Holdon 6 Camshaft.
Performance Wholesale in QLD deal with them, give them lobe number's you want, separtion etc and 2 weeks later its in Australia.
I've been told that Comp have steel billet's to grind you a roller but they only list cast core's on they're site.
The Cam was 301/307 @ .020
272/276 @ .050.
180/184 @ .200
and .590" valve lift on 105 Center's.
Was advised to not add anymore ramp without regrinding lifter's otherwise it would be impossible to keep lobes on it.


Greens Nice - Certainly looks like an aggressive lobe. What lobe profile (or 'family' of lobe profiles) did you use?

#43 greens nice

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Posted 03 May 2012 - 05:34 PM

IIRC the intake was an XTQ and exhaust High RPM II
cam has .392 lobe lift so i used 1.5 rockers. Lobe separation is 108

The only problem i have with the Comp grind's is that they are all mega lift (for a holden 6 anyways) and it can be very difficult to get that sort of lift with the 1.72 int valve i used.
I have it written down somewhere but i think after moving the head over .090 I ended up with .050 piston to block clearance and all is good.

cheers

#44 2600s

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Posted 03 May 2012 - 09:34 PM

I called Trent at Clive Cams today to discuss cam options for my LC GTR.
After advising him my engine will be kept basically in stock configeration,Trent suggested a cam called a "161", nothing to do with my engine, he thinks this would be the a lot better for performance than a "XH" for my engine as this was another cam option we discussed.

I was pleasantly suprised by the price, $205, Trent also suggested he supply two piece lifters to go with the cam.

Thanks for the "heads Up" guys!

"Cheers"

Alf

#45 _Bluejinx202_

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Posted 04 May 2012 - 09:54 AM

The only problem i have with the Comp grind's is that they are all mega lift (for a holden 6 anyways) and it can be very difficult to get that sort of lift with the 1.72 int valve i used.
I have it written down somewhere but i think after moving the head over .090 I ended up with .050 piston to block clearance and all is good.

cheers


Would you mind explaining this bit for dummies like me?

Why does the head need to go over? And 0.050 piston to block clearance means?

#46 73TORANA!

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Posted 04 May 2012 - 10:50 AM

Moving the head over is an old trick it allows better flow around the valves on the plug side ,I.E it moves the valves slightly towards the middle of the bore and away from the cylinder edge on the plug side . This will help any holden 6 .
But you must look at a few things , water gallies and push rod hole line up with correct clearance. OLD JOHNNO wrote a nice piece on it ,he might be able to send you a link to the page im sure if you ask nicely. Previously in this thread it explains why these new school cams work better but yeh it can be all a bit of that Haryy Potter magic especially when everyone seems to measure there cams differently . I think that pretty much right , Old johnno can you confirm .

Edited by 73TORANA!, 04 May 2012 - 10:57 AM.

#47 73TORANA!

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Posted 04 May 2012 - 11:23 AM

Forgot to add, moving the head in this case with 1.72 inlet valves is to make sure the clearance of the valve at full lift to cylinder wall at the top of the bore is adequate. Sometimes its call butterflying the block from memory . the 73 Bathurst blocks had this butterflying done.

Would you mind explaining this bit for dummies like me?

Why does the head need to go over? And 0.050 piston to block clearance means?


Maybe a type "O" . Should it be valve to block ?

#48 greens nice

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Posted 04 May 2012 - 12:39 PM

Forgot to add, moving the head in this case with 1.72 inlet valves is to make sure the clearance of the valve at full lift to cylinder wall at the top of the bore is adequate. Sometimes its call butterflying the block from memory . the 73 Bathurst blocks had this butterflying done.



Maybe a type "O" . Should it be valve to block ?



Ahh woop's............. Yeah i meant valve to block clearance.

#49 73TORANA!

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Posted 04 May 2012 - 02:49 PM

Hey greens nice , (yes it is ) ,
How much did you have to take off the valve guide and what springs did you use to stop it all binding up.

Cheers , Geoff.

#50 greens nice

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Posted 04 May 2012 - 06:14 PM

Nothing off the valve guide, engine has v6 Buick valves in it, theyre .200" longer than standard IIRC
Springs, retainers and lock's were from Comp and Crane.
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