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Best slant Performance manifold
https://slantsix.org/forum/viewtopic.php?t=24765		 Page 1 of 1
Author:  68barracuda [ Mon Sep 03, 2007 5:21 am ]
Post subject:  Best slant Performance manifold
Hi Guys,

I want your opinion on this

I have the following available

An Atkinson's Power Pack : twin 36DCD7 Weber's feeding the engine through
a "banana branch" l inlet manifold with a balance tube between the plenums
track length ~12 inches

An Offenhauser/Clifford look-alike manifold, but supplied by Chrysler over here in the late seventies, with a 465 CFM Holley 4150 Vacuum secondary

And a Supersix setup - kinda - cast-iron instead off aluminium

I am upgrading the head with a bit off skimming, larger valves, pocket porting and unshrounding the valves, as well as a 5 angle valve job

I hear 6-2-1 headers are the best option

So suggestions please

It is in a 68 barracuda fastback - used for cruising and a bit of racing

Fanie
Author:  66aCUDA [ Mon Sep 03, 2007 6:34 am ]
Post subject: 
Fanie
I think Either one would be ok. I have looked at the 3 deuce Weber set up for my race car. The Holley would be easiest to tune. But Ive been told that the Webers can be tuned to get every bit of power out of each cylinder. My Last trip to SA was years ago if I remember Webers were very common there.
Good luck and let us know what you choose. :D
Frank
Author:  SlantSixDan [ Mon Sep 03, 2007 6:37 am ]
Post subject: 
You don't really have any bad manifolds there! If I were you, I'd probably look at choosing between the dual Weber and the 4bbl. If I were me, I'd pick the dual Weber 'cause it's cooler than a single 4bbl! :lol: :twisted:
Seriously, I think it depends on which kind of carb (and how many of them) you'd rather futz with until the engine runs well.

Minor details: "Super Six" was the marketing name given to the 2bbl package offered in North America from '76-'82. The intake was in various years made out of cast iron and out of welded-up aluminum. Neither is the same intake manifold as the export 2bbl intake ('67-up) you've got. The export intake has no EGR provisions and an open plenup rather than a 2-hole plenum.
Author:  LUCKY13 [ Mon Sep 03, 2007 8:34 am ]
Post subject: 
THe Duel Weber.




Jess
Author:  68barracuda [ Mon Sep 03, 2007 12:07 pm ]
Post subject: 
Quote:
Minor details: "Super Six" was the marketing name given to the 2bbl package offered in North America from '76-'82. The intake was in various years made out of cast iron and out of welded-up aluminum. Neither is the same intake manifold as the export 2bbl intake ('67-up) you've got. The export intake has no EGR provisions and an open plenup rather than a 2-hole plenum.
Interesting - i chose to use this term because it describes the manifold reasonably well - a lot of the guys from your side does not realise we had this option already in the late 60's - sorry :oops:

The dual 36DCD7 is tempting - I had some dyno comparisons at one stage between the 4 barrel AFB setup we had over here in the late seventies, and this dual weber, and in the same car with the same engine a higher hp output as well as torque, as well as a better torque spread was realised

The holley works quite well and is easy to tune - my only concern is the fuel distribution - I was wondering what a 90 swing in carb orientation - primaries furthest away from the engine would achieve
Author:  SlantSixDan [ Mon Sep 03, 2007 1:52 pm ]
Post subject: 
Without seeing pictures, it seems to me the 2-carb manifold would be better on fuel distribution, for the runners are of more nearly equal length. Is there something about this setup that suggests it might give uneven mixture distribution?
Author:  68barracuda [ Tue Sep 04, 2007 12:35 pm ]
Post subject: 
Quote:
Without seeing pictures, it seems to me the 2-carb manifold would be better on fuel distribution, for the runners are of more nearly equal length. Is there something about this setup that suggests it might give uneven mixture distribution?
The biggest issue is getting the carbs synced - a mannometer makes this a lot easier

As far as distribution is concerned the thing it screams to me, cept for way cool looks, is ballance all the way
Author:  VG-265 [ Fri Sep 07, 2007 7:22 pm ]
Post subject: 
Quote:
Minor details: "Super Six" was the marketing name given to the 2bbl package offered in North America from '76-'82. The intake was in various years made out of cast iron and out of welded-up aluminum. Neither is the same intake manifold as the export 2bbl intake ('67-up) you've got. The export intake has no EGR provisions and an open plenup rather than a 2-hole plenum.
I wasn't aware the 2 barrel manifold we got was different to the ones you got.
Learn something new every day.
Author:  SlantSixDan [ Fri Sep 07, 2007 8:09 pm ]
Post subject: 
Quote:
I wasn't aware the 2 barrel manifold we got was different to the ones you got.
It's even more fun than that...! The 2bbl intake used in Australia was made in Australia, complete with A-suffix casting and part numbers. The one used in South Africa, Spain, Central/South America and other export markets was a US-sourced part (or at least made from US-sourced drawings). The Australian and US Export 2bbl manifolds are very similar, but not quite identical.
Author:  68barracuda [ Fri Sep 07, 2007 9:37 pm ]
Post subject: 
And to take it further - the /6 engines Torqueflite gearboxes - all heavy metal work was done locally - RSA, and the 4BBl manifold used from 76 to 80 was total local as well :D

As well as those "other manifolds" heh Dan :twisted:
Author:  68barracuda [ Fri Sep 07, 2007 9:41 pm ]
Post subject: 
Oh yes the differential up to the VH was based on US designs, from VH upwards it was a local heavy duty unit - this I heard this week from a Local Chrysler engineer.

I was wondering why I could not find any similar rear end's - covers differ - looks like a US 8 1/4.

Hopefully he will be able to shed some light on this :shock:
Author:  PiDstr [ Sat Sep 08, 2007 8:01 pm ]
Post subject: 
68Barracuda:
I can recommend the dual weber downdraft set up - I run one with a pair of 32DAR carbs (off a Renault 16TS, so 28mm choke), it deals with the daily traffic grind in here in Melbourne well, crusing along on just the primary choke, and runs away from the unsuspecting hoons when I bury the foot and open up the secondary's.

If you can concentrate on just using the primary's, it returns resonable fuel economy, but forget about economy when 'driving briskly',.... ;-)

If you do use it, use two return springs on the shaft that links the two carbs to the throttle cable - one spring that is under tension all the time, and the second one of the type that has a hook on a short shaft at each end of the spring, which you can then bend/adjust to make the spring work when the secondarys are open, that way you can feel the change in foot pressure needed as you go from primays only to primarys and secondarys together.

PiD v4.0
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