Cam and Valve questions with the Aussie 2V head

[Anonymous]

I am trying to figure out which camshaft I should run. I am building this motor for my Aussie 250 2V build up. I have a C4 with 3.00:1 gears in back. I've been told that a 280 cam is too much for this setup and I will lose my power.

Can I run a 272 cam, or is that still too much? Who should I get this cam from?

Also, if I have the valve guides in my Aussie head changed, can I run standard American valves? Should I have the head cut for bigger valves?

What brand of springs, retainers, lifters, etc. do you recommend to go with the cam you suggest?

 

[Anlushac11]

8)

A 272 will run with an auto but will idle rough. With you gearing I wouldnt go over the 260 cam.

I recommend getting the complete cam kit with all the springs, followers, retainers, and lifters. A matched kit from one manufacturer designed for a certain cam profile is hard to beat.

 

[Anonymous]

I can live with the rough idle. Will the 272 have a significant gain in performance?

 

[xctasy]

A 250 six is a big engine with lots of effective compression, long stroke and a smaller port head with limited air flow than most Australian cross flow sixes. If the inlet /outlet 50 thou duration goes over 215 degrees, the car can fall into an off-idle hole with a stock converter and auto with shallow gearing. If it's got power steering, there is an added parisitic loss on full lock in the city. Cam grinders care about getting the right cam so these factors don't create a problem with drivablity. My experience with cammed Falcons is limited to a 280 degree cam on an XF Falcon with EFI. I have no idea what the 50 thou open duration readings were. This provided bulk mid range without harm to low end. I'd personally go for this as a maximum.

A cam supplier should state what works with a stock 250. A 2V head drops gas speed, and may be more cammy than a stock 1V, but it will also be less cammy than the big ported cross flow.

If you dropped the axle ratio to 3.25:1 or so, and use a 280 degree cam with a higher stall speed, like 1800 to 2250 rpm, then you'll get a standout performer, with real urge off line. If stock stall and axle ratio are to stay, then a hydraulic 280 degrees should be the limit.

 

[Anonymous]

I am going to be running a 200 CID motor. Should I go with a 272 cam then?

 

[addo]

It's been my impression that Aussie cams had a larger difference between the "ADV. DUR" and the ".050 DUR" figures, compared to US grinds. Lobe profiles may vary beyond that, too.

Check out Crow cams' Aussie website for some honest, conservative cam recc's/specs. Generally, they recommend #13603 or #13666, from memory. It's very important not to overdo the valve springing, too.

It also comes down to how fast you want to break it. Seriously, there's no point overcamming. It will simply reduce the ratio of satisfaction life to dollars spent.

Cheers, Adam.

 

[Anonymous]

So a 272 cam will give me good performance and life expectancy? What are the performance differences between a 260, 262, and 272 cams?

Also, when I take it to the machine shop, can they put US guides and valves in the OZ head?

 

[addo]

...when I take it to the machine shop, can they put US guides and valves in the OZ head?

Yes. I advocate this because you can convert it to SBF trim. I doubt the $2.50 valves Ben scored from Oz were swirl polished, back-cut stainless Manleys, Milodons or FMS...

Simply, it's a good chance to fit bronze guides, and valves that will be easily serviceable in the future. You're building something that will be easy to find parts for. The only two hassles are: The tip height will change slightly - may need to shim the rocker pedestal 0.010 or something, and that the pushrods may need replacing with marginally longer ones.

Valves' spring assembled height may vary from SBF, so check this to evaluate actual spring pressures.

It's implicit above, so I'll say it clearly here: Talk to Mike about the "Street Terra" full roller rockers. You won't go back.

Hope this helps...

Regards, Adam.

 

[Anonymous]

If I get the full roller rockers instead of the roller tip rockers, is it easier to covert to SBF valves? Do I need to get different valve springs or locks when I use SBF valves? Where can I get the oil thru lifters and push rods?

 

[addo]

If I get the full roller rockers instead of the roller tip rockers, is it easier to covert to SBF valves?

Yes. You will need a small shim of ground steel plate cut under each contact area of the rockers' mounting base. If the geometry is able to tolerate a mild change, this may even be not needed. Check to be 100% sure.

As for the valve springs and locks: Locks that suit the valve. They will likely be different to stock Aussie. Springs? You will have to dummy up the valve in the head with the seats cut in, and the gear on the tip of the valve. Measure the space in between the seat and the underside of the retainer, and use this to choose the correct spring.

Pushrods: Manley can still make custom sets, I believe. It may be that the 9.140 set will fit OK. Lifters are SBF units - get anti-pump for large cams, stock for smaller grinds. Cheap and common!

Cheers, Adam.

 

[Anonymous]

Man this thread is right up my pathway.

I am building the same setup with a couple of minor exceptions.

I decided to drop the Weber and go for the Holley 2300 500cfm 2bbl.
I am bead blasting and polishing the 2v intake.
Fitting all US valves in there, with 1.75 intake and bronze guides.
Full Roller rokers with lifters and rods to be changed as well.

I was thinking a 260 cam and going mild on the pistons staying with a cast piston looking for a 6.5cc dish size.
Measure and deck to achieve 9.1:1-9.2:1 on compression with clearance issues resolved. Balance and rebuild other block componenets.

Running on the new engine:
Adjustable Timing Gears
Hi-Po oil pan
DII with MSD 6A
Dual outlet headers to dual exhaust
93 WC T-5 (5.0 swap)
8" trac-loc rear with 3.25:1 gears (upgraded to 5-lug, had too do it!)
15X7 wheels all around, and front disc, rear drums power brakes.
Manual steering.


So, how does that look....
I was doing a 4cyl T-5 swap, but after talking to some people about it, we thought this 200 was a bit much for it and it would be better to drop the gears and go with the 5.0 version. This car will see a lot of highway time. So I need to get a compromise between off the line power (which we all want) and high RPM power on those freeway lanes.
One thing I am still looking at is using the 260 cam with the new manual setup, maybe I should go a bit higher on that?

I am as always curious what thoughts there are about this configuration.

I am getting closer to being done with this plan, and having the parts needed to get going. Things are starting to appear in the garage. SWMBO is asking too many questions lately!

 

[Anonymous]

Jimbo, I to am building a very similiar setup. I just purchased an Aussie head. I'm having new valves put in, 1.75 intake valves and 1.5 exhuast with 3 angle valve job. I'm also looking at a 500cfm Holley and a 262 cam. The head should almost be done. Hopefully I will get it on the block sometime in January get it dynoed and post some results. See how it compares to Mustangroo's results. Once it's tuned and running fine I will pull the engine out and do the rest of the work.

Let me know how things go wth your build up.

 

[Anonymous]

I just got off the phone with Comp Cams . . .

They can custom grind me the following cam:

Straight cut pattern (numbers are w/ 1.65 rockers)
.495" lift
270 duration
224 duration @.050
110 separation
4 degree advance

Does this sound good?

 

[MustangSix]

Personally I think that's a little too much cam for that drivetrain combo.

Talk to the cam folks again, but IMO, on a 200 with a stock converter and gears your .050 duration should probably be between 204 and 210 degrees.

 

[Anonymous]

Jack, would it still run okay? I might change the gears and converter when it isn't my everyday car. I don't want to get the 260 and have to change it later. Will I lose performance with the 270 grind?

 

[Anonymous]

I have a 262 deg cam and I think its too much.

Boy it really opens the engine up though once I get at around 3 or 4 thousand. Then it promptly shifts.

If you were gonna go with a T5 and some deep rear gears I'd say go for it. With a C4 though you won't ever see the benefits of a rowdy cam like that, unless you change the stall.

Anyway personally I'd rather have a 256deg cam with some good lift.

 

[addo]

A smaller cam is good because it stresses the engine less. So things last longer.

A bigger cam is good because the performance may be much higher.

You have to consider if engine life (between rebuilds) really matters, how the car will really be used, and if the high performance cam is able to hit its straps before you run out of road, license or fuel.

:roll: If you're going to spend all this money, do it to enjoy your car yourself, not to simply impress others...

This cam issue is where VCT is really nice. Bugger...

 

[Anonymous]

Is .480-.495 lift going to create clearance issues with my valves? Is there anyway to know for sure without doing a mock up assembly?

 

[MustangSix]

I think that a 224@.050 cam will be a less than optimal choice (in this case) for a couple of reasons:

First, it may have a tough time idling against a stock converter. The idle will probably be around 900-1000 rpm and a little lumpy to boot. You'll be on the brakes all the time just to keep it stopped and on the gas to keep it from dying because it's up against a low stall speed.

Second, it'll have very poor low speed characteristics. A cam that large will not make any more power than a stock cam until it reaches maybe 2500 rpm or so where the curve begins to rise. Up to that point, it may make less. So from 0-to 50 you could have a big cam, great head, loud exhaust and actually go SLOWER because you don't have the gearing to match the power curve.

Third, it's going to pull very little vacuum at low speeds. That's going to mean little vacuum advance, and even higher throttle openings. All that translates into very poor fuel mileage.

Now, if you go with a 2200-2400 rpm stall converter and 3.50 or better gears, this becomes a good cam. A 280 or 300 degree cam becomes a viable option with 3.73 or better gears. With a stick, it's a good hot cam.

As far as the lift, if you go with a big lift cam, you MUST do a mock up. You'll be deviating from stock and doing a one-off unique combination. Measure, measure, measure.......You may be ok, you may not. Only one way to know for sure.

I'll do a couple of runs with EA to verify all this, but I think you'd be happier with the 260.

 

[Anonymous]

Jack,
How can I fix valve clearance issues? Will dished pistons help at all?