Cam selection for US200/Crossflow

I've touched on this before, but now that the new house (and GARAGE) are just 9 days away from being MINE, I can start planning work for the Crossflow project again... at least in theory.

Here's what I have:
US 200 block (stock)
Alloy Crossflow head (stock)
Redline 4V intake w/ Holley 650 DP (may go w/ a smaller carb like a 2V 390)
Genie headers
Roller tip rockers

Here's what I'm getting, hopefully before springtime:
C4 auto trans w/ 2000 rpm stall TC (Stall speed is subject to change)
8" rear w/ 3.50 gears (and some form of locking action, TBD. Ratio subject to change)

I'm going to be shooting for about 10:1 CR during the machining stage. I don't plan on having too much done to the head... just the usual valve job, some better springs, etc. I think I want most of the power to be coming in from about 2K-4Krpm even though I'll be building the bottom-end of the engine to handle 5500rpm. The head is going to flow plenty and w/ those big ports and the auto trans, I know I need to be careful about over-camming and fubar-ing the idle and low-end performance.

My gut is telling me the Crow 14776 is a good choice. http://www.crowcams.com.au/templates/Catalogue-Falcon6Xflow.shtml

Am I in the right ballpark? I thought I had this stuff all figured out last year, but I've gotten rusty since my employer blocks access to fordsix.com and I haven't been able to make any car part purchases while saving for the house.

Assuming standard rocker ratio, that'd be a safe bet. Make sure you follow Crow's recommendations for springs, locks, retainers etc. The specs of these parts will be conservative already, and to go heavier again is overkill/waste energy.

You can probably go a shade higher on compression than suggested by them, as no distinction is made in the grind between alloy and iron heads.

Shipping on cams is expensive due to the weight. I posted one and airfreight was AUD$70, two years ago. Now you can at least draw down on your equity to fund the projects. :roll:

Cheers, Adam.

First rule of cams is "never over cam a street car with a free breathing head". All the hot Fords ran very mild cams on the later engines because the heads breath better. In cases where they were real hot ones, like Cobra Jet 429's and Cleveland 351'S and Boss 302'S, they ran screaming diff ratios and if they had an auto option, it was high stall.


Onthe 200 sixes with the Aussie Alloy head, the working range of cams is really the stock (#14678) EFI XF series 250 cam to the (#14892) 280 degree, 214 degree at 50 thou lift cams.

If it works on an Aussie 250, then it'll work on a US Jack'ed' up X-flow 200, but there are a list of constraints.

a) a lot more idle chop,

b) a higher rev range,

c) a higher peak power

d) and a higher peak torque rpm.

(I got these from Bob Matic in Australia. When asked about how 351 V8 cams went into a 16% smaller 302, he listed that the shorter stroke engines were much more choppy at idle. Something like a 1988 CC 260 cam would run fine on a 351C, but would be close to unstreetable on a 302C, even though only the stroke ands rod ratio were the only changes).

This is becasue of the US 200 has the same rod ratio as the 250 but less 25% leverage in each cylinder. This is why the curb idle and the basic rev range is always going to be a little higher.

On a 4.1, the stock XF series EFI cam gave about 4500 rpm tops, with power at 4000 rpm, torque at 3000 rpm, but with a 90% of maximum torque available from 1500 to 3500 rpm. Idle is like 600 rpm.


The same cam in a 200 would give a 5500 rpm rev range, maximum power at 4500 rpm, maximum torque at 3200 rpm, and a higher idle speed. The wide low end torque spread would still exist.


If you go for the dual patern 14776 it is designed for a restricted exhast Falcon 4.1, and I'm thinking that you could loose a lot of low end torque with a stockish automatic.

I'd stick with a milder cam, especially if you have only three gears.

David Vizard covered the selection of the right cam about 20 years ago on litle Pintos and Cortinas with 2.0 engines and C4 automatics. His overriding theroy was that automatics with factory option stall ratios hate any more than 205 degrees duration at 50 thou. Look at 351 2V Clevelands with automatics, they either ran 256 degree cams (185 degrees at 50 thou) with an FMX with a 1650 rpm stall. The first of the 351 4V Clevelands ran some kind of 280 degree cam (210 degrees at 50 thou) with a very high stall converter (2350 rpm). Nothing over 215 degrees at 50 thou.

When you cam smaller engines over that 205 degree at 50 thou level, they fall into and off idle hole. If your cam raises the rev range, it just makes the situation worse. This is why I favour a greater ratio spread (4 or 5 speed gearboxes), or to stick with the smaller camshafts.


Final clarification. Back in 1987, Wheels Australia tested an SVO Falcon XF with a stock EFI engine with a 280 degree, 214 50 thou duration cam, wide ratio 5-speed and tall 2.77:1 diff.

It worked really well. With a 3-speed automatic with 1650 stall converter it would be getting getting border line.

On a car with 25% less capacity, it would mean the 14776 would be the highest cam duration I'd look at.

Thanks for the wealth of info! Here's my plan of attack:

Start out with a stock EFI cam or #14678 and about an 1800rpm stall TC and 3.50 gears. I'll work out the rest of the kinks in the setup (carb, ignition, cooling, etc.) and see where I end up.

If I feel the need for more cam, I'll swap to a #14771 or similar cam and see how that works with the TC. If need be, I'll bump up to a 2Krpm stall speed TC and increase the idle accordingly.

Am I getting closer?

Sounds a whole lot safer.

Talk to Crow Cams. Tell them what you want. They have a specialised Engine Analyser program for there own benifit. Talk or Email Ron Spencer and see what he says.

Simple rule is the person selling the cam has to sing for his supper.

Chris Gable from Street Machine Australia interviewed Ron Spencer 15 years ago and publicized his work in "Tough 6's".

Ron did some specialist roller cam work for a Texan racer called JR in 1990. They made a roller cam for his Eccono Drag racer. Of that, Crow marketing man Robert Henty said in 1990

"It's ironic in a way that we (Australians) are taking six cylinder engine technology to the States".


It seams that we have lost 15 years of information somewhere, so my guess is hit up Crow for some info.