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2BBL Carb running parallel
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Author:  SV162 [ Thu Oct 28, 2010 10:12 pm ]
Post subject:  2BBL Carb running parallel
I'm thinking of modifying a 1BBL intake to take a 350 Holley. The plan is to run the carb parallel with the engine, the question is, should I have the carb set-up so the throttle plates open in a clockwise direction(looking from the front of the car) so the air/fuel mix is directed away from intake runner 3 and 4? Or would it be better having them open the other way directing the air/fuel towards 3 and 4?
I'm leaning towards the first option, my thinking is at part throttle the 3 and 4 cylinder will run rich if the fuel is directed straight at them.
On the other hand having it that way will position the fuel bowl of the 350 Holley away from the exhaust heat. :?

Any advice is greatly appreciated. :)
Author:  emsvitil [ Thu Oct 28, 2010 10:20 pm ]
Post subject: 
That makes sense to me.................
Author:  SV162 [ Fri Oct 29, 2010 9:02 pm ]
Post subject: 
Quote:
That makes sense to me.................
That makes one of us. :)

Seriously though, you're saying it makes sense to run the carb with the fuel bowl facing the engine?
Author:  emsvitil [ Fri Oct 29, 2010 9:45 pm ]
Post subject: 
I don't know where the fuel bowl is.................

I was going with this:
Quote:
The plan is to run the carb parallel with the engine, the question is, should I have the carb set-up so the throttle plates open in a clockwise direction(looking from the front of the car) so the air/fuel mix is directed away from intake runner 3 and 4
Author:  SV162 [ Fri Oct 29, 2010 10:08 pm ]
Post subject: 
Yep, that's what I thought. Thanks.
Author:  Dart270 [ Sun Oct 31, 2010 8:01 am ]
Post subject: 
I have always run it with the fuel bowl toward the left fender, when I've tried that transverse mounting. Not sure there's much difference. For the drags or regular street use, sideways mounting is fine, but fuel slosh kills you on turns (RH turns if fuel bowl toward left). I think the car ran identical times at the dragstrip with the carb transverse or longitudinal.

I think the gains will be in part throttle operation on the street, between the different directions.

Lou
Author:  SV162 [ Sun Oct 31, 2010 5:41 pm ]
Post subject: 
Thanks Lou, I would be mounting the carb east/west to improve fuel distribution at part throttle.

Here's a related question for you Lou. I've read that you've been using the Aussiespeed 2BBL intake and that you believe it has very even fuel distribution, is that still the case? Are you still happy with it's performance?
Author:  Dart270 [ Tue Nov 02, 2010 8:57 am ]
Post subject: 
AFAIK, Slant 6s have pretty even distribution in general, with almost any manifold. I have not checked this in particular on the Aussiespeed manifold.

However, I can tell you that the low-mid range power is great, and you can WOT rev it in neutral or in gear and there are NO bogs. I tried jets over a large range, and NO bogs. Even with no choke and a cold engine, minimal to no bogs. I am impressed with this throttle response. Most bigger carb combos will show some bogging under different conditions and this manifold appears to be better.

This motor does appear to stop pulling around 5500, and I feel it should pull better up there for what is in it (big cam, ported head, 11:1...), but I need to try bigger exhaust and/or a different manifold to know if it is due to the Aussiespeed intake.

Lou
Author:  coconuteater64 [ Tue Nov 02, 2010 10:03 am ]
Post subject: 
I am running this carb in the same orientation the factory ran the Carter BBS (fuel bowl to the front) and whether or not it makes any difference, who knows. But this is one dynamite carburetor for the money!
Author:  Doc [ Tue Nov 02, 2010 11:06 am ]
Post subject: 
We have never seen or confirmed any changes in fuel distribution or power with carb orientation changes. As already noted, this seems to be influenced more by over-all intake manifold design, then carb orientation.

We have see driveability changes with carb. orientation.
Fuel slosh can cause starvation and a "dead spot" when the carb is mounted "sideways" and you drive fast, into a hard corner and try to accelerate out.

The same fuel slosh problem actually happens with conventional bowl forward carb. mounting, when you do hard braking but that does not cause much problem... seeing that you don't usually need engine acceleration and hard braking, at the same time. Bad slosh can cause the engine to stall, after an abrupt stop or spin-out.
DD
Author:  SV162 [ Wed Nov 03, 2010 6:03 pm ]
Post subject: 
Thanks to all, that's all good info.
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