Would i have any problems using a well ported head with larger than stock valves with a BBD?

I don't think there would be a problem, but a slant with larger valves will then move your performance bottleneck to 'need more cam, need more compression, need a 4 barrel carb...'

The BBD is so small I don't think you'd need bigger valves yet...


-D.Idiot

im going to rebuild my engine soon so while it was apart i wanted to get as much done as i could. i plan on running more compression, more cam and so on but i would like to stick with the bbd to the realm of its performance level. im wondering what cam i might run. 70valiantis in the high 16's with a BBD, are 15's a possibility?

you can do a heck of a lot with a BBD, they used them on 318's. I think high 15's are possible with a moderate cam and serious gears. we could not get the 8.75 rear w/ 3.91's together for pittsburg so I found a cheap 8.25 w/ 3.21's and took a quarter second off of my ET. 3.91's and a comp cams 252 and high 15's are in my future.

_________________

i want to build the car to at least run in the low 16's and maybe the 15's. someday im sure a 4 bbl will make its way onto the engine but for now ill take what i can get with the bbd. so i shouldnt have any problems with larger valves, a more aggressive cam, ported, polished and decked head, with the bbd?

i guess a question i have is will the larger valves give me a performance boost coupled with the bbd? or will this just be an upgrade that wont shine till i swap to a 4 bbl carb?

I appears that some of the export \6's used a bigger valve head with the BBD to produce 180hp. Some of the folks from Austrailia may be able to shead some light on the subject as their Valiants had a 180hp \6 option.

does anyone have specs on the size of the valves used in the australian slants?

G'day,

Our valve sizes are:

Intake - 1.615-1.625"
Exhaust - 1.355 - 1.365"

Valve lift is listed at 0.395" for both intake and exhaust.

Hope this helps,
Eyman

Interesting, so what is this "180 hp \6" that the tales of the Aussie Valiants but forth?

heres my recipe for my car at this point:

74 2 door swinger
stock electronic ignition
225-.30 overbore
stock replacement pistons
larger valves
port, polish
deck the head (how much would yield me about 9.0-9.5 compression?)
carter bbd on a super six intake
headers, 2.25 in single exhaust into a flowmaster
rebuilt 904
3.23 geared 7.25

does this sound good for at least 16's and possibly high 15's? to tell you the truth the car wont see much drag duty but when it does this is the performance im shooting for. but mostly ive got a buddy that drives a 96 Thunderbird with a 4.6L that runs 15.77. he needs a little eye opener but i dont have the cash to do something more than once so i gotta get it right the first time. what do you guys say?

You're probably thinking of the VF Pacer, our "high performance" slant. The VF Pacer was as rated at 175hp, and was identical to the 160HP engine with the exception of compression ratio (9.2:1 vs 8.4:1) and cam duration.

If the Aussie slant was using BHP, then our 1 barrel 225 was rated at 145 BHP, a super six intake might make that 'about' 160BHP...then say a kick in compression and a little bit more duration and lift might get that up a bit more....


Lemons and Lemonade...

-D.Idiot

We effectively had three slant engines on sale here in Australia. - 1BBL, SuperSix, and Pacer.
From 1962-1967 1BBL only, 140HP
From 1967-1970 1BBL @145HP, 2BBL @160HP
From 1969-1970 "Pacer" 2BBL @ 175HP

1970 saw the introduction of the Hemi 6:
Hemi 215 1BBL - 140hp@4400rpm, 200lb-ft@1800rpm
Hemi 245 1BBL - 165hp@4400rpm, 235lb-ft@1800rpm
Hemi 245 2BBL - 185hp@4600rpm, 240lb-ft@2000rpm
Hemi 245 4BBL - 211hp@4500rpm, 237lb-ft@2500rpm

1972 saw the Hemi 265 introduced
Hemi 265 2BBL - 203hp@4800rpm, 262lb-ft@2000rpm
Hemi 265 "Pacer" - 218hp@4800rpm, 273lb-ft@3000rpm
Hemi 265 E49 6Pack - 302hp@5600, 237lb-ft@4100rpm

And there you have it. There are more Hemi engines around that I haven't listed, but you can see why the Slant is not the preffered 6 of choice for most Aussie Valiant fans. The Hemi also had a competition history here in Australia, and coincided with the height of the muscle car phase.

Sorry to have taken this thread off-topic, but I hope this sheds some light on our cars downunder.

cheers,
Eyman

I did exactly what you are talking about as I was building my turbo/slant. I kept the BBD after the engine was built, but before the turbo was on, because the BBD is such a good carb. I got another easy 500 RPM by porting the head and installing larger exhaust valves, but still with the BBD. It is worth doing. I did not feel like I lost anything with that move. It is important not to make the intake runners any larger than stock because you want to keep the velocity of the mixture up through the runners.