CARTER RBS v. AUSSIE HEAD

[Anonymous]

Thanks for looking—I’m soon going have to decide if I want to do something about the asthmatic performance from my ’76 250. The tranny’s coming out, and so I might as well do any engine work at the same time. I can stick with the stock set-up (Carter RBS) and keep buying high octane or convert to an Aussie head, two-barrel and headers (but with the stock cam).

When I run high octane through my RBS, the engine runs damn smooth (except when it vapor locks on 110 degree days in Phoenix).

Does the Aussie head give that much more pedal power?

What are your thoughts?

67 Mustang coupe—Granada 250, O/D tranny, & disc brakes, 68 Cougar rearend, 81 Fairmont drive shaft all installed with my English teacher’s hands and Craftsman tools.

 

[xctasy]

The head in itself comes with a 2-bbl carb, tube headers, and brilliant intake ports. So it yeilds an easy 45 hp more than the stock 85 to 95 hp net a US 200 or 250 log gives. This is backed up by a few dyno runs on forum member cars in even the mildest tune.

No bolt-on mod is as effective.


You have to trade off the cost of a head, which will need a rebuild with good American valves. There is minor difficulty in packaging the 2-bbl carb under a Mustang hood, but 45 hp is 45 hp, with no need for more revs.

The stock US 200 and 250 cam is a 252 degree tractor item, with torque at 1600 rpm, power to only 3500 to 4000 rpm, tops. Even if you stick with it, the 2V head will add a lot of power. Best cam is one of the 264 degree aftermarket kits from FSPP. Apparently, the 2V 250 from Aussie ran a sligthly wilder cam than the stock US 250 item. The stock Aussie 250 was rated at 155 hp Gross, just like the 1969 US 250. The 2V was rated at 170 hp gross.

Funny thing is the stock Australian gross power readings didn't line up very well with the facts. In 1972, a 130hp 200 did 18.5 second quarter miles, the 155 hp 250 did 18 second quarters, the 170 hp 2V 250 did 16.9 seconds, and the 240 hp 302 2V did 16.9 seconds. The truth is the six had heaps more than 15 extra ponies.

 

[addo]

Show me a different part number for the 2V cam. While you're at it, the dizzy, too. I believe the bottom end was 100% stock Ford, no variations.

Lift at lobe measured by me was 221 thou inlet, 229 thou exhaust. Didn't dial the duration.

 

[xctasy]

Ooops. Adam scores the KIN-NOW-LEDGE!

Cool, stock 252 degree cam then for a 2v. All the power was through a head. If your Mustang with Granada engine gives an 18.0 second qauter mile, it'll drop to 16.9 with just the 2V head and tube extractors.

Adam confirms, the head is the only difference in 1.1 seconds of extra power over a standing 1320 ft dash. That's actually worth 21 hp, or 17 rear wheel hp.

American 250's are encumbered with EGR, PVS and other emissions gear, so its nothing to see an unemissionized Aussie head yield lots more power than that. Especially if it has a 350 Holley, 38mm Weber or 500 cfm Holley on it.

 

[addo]

I'm mainly concerned with people selling something that's no different, to the unwary - like a "Genuine original 2V shortblock" or similar.

(Want to buy some OEM GTHO Phase III grease caps? )

Not wanting to shout down knowledge or real HP at all.

Thing about the 2V, is as a 250 it was well-matched by Ford Oz. Just the 2V head assembly on a US 250 will improve things, but not as much as the same head and bits on a high compression 1972 Oz block. (It really seems harder again to spread the sweet spots of tractability and economy evenly across the motor's bandwidth on a 200 block.)

As to the original case in question - a solid build on the block and good ancillaries would support either choice down the track.