318 2bbl BBD flow? Improvements?

[318willrun]

I wondered if anyone flowed a 2bbl BBD from a 318? And ways to improve flow?? Size of the venturi for possibilities ???

Thanks for any experiences you wish to share.

 

[rumblefish360]

If you change the butterfly size, you need to readjust the angle of the blades. Don’t do it.

You would be better off ovaling the 2 barrels into one and crating a new I so plate instead of two round ones.

 

[318willrun]

If you change the butterfly size, you need to readjust the angle of the blades. Don’t do it.

You would be better off ovaling the 2 barrels into one and crating a new I so plate instead of two round ones.

my thought is.... and this is what I believe on all carbs, is that the venturi size is the dominating factor, not the butterfly size. Your potentials are limited to the venturi size.

 

[rumblefish360]

True. If you decide to bore the venturi larger, your changing a bunch of aspects of the carb. If the carb was small for the engine, you’ll probably pick up lower easy enough. I think that would be the case.

Oh… I plan to try this on a TQ once I get a few things sorted out around here.

 

[RustyRatRod]

Use a Holley 500.

 

[rumblefish360]

It doesn’t keep with a theme, cheap.

 

[318willrun]

Use a Holley 500.

It doesn’t keep with a theme, cheap.

This is for a specific project that has to use the 2bbl bbd. I know throughout my years there are different sized venturi's that came on these.

 

[RustyRatRod]

This is for a specific project that has to use the 2bbl bbd. I know throughout my years there are different sized venturi's that came on these.

Get one off a 383.

 

[rumblefish360]

I’m not sure at all of the various sizes though I’m sure a 440/400 2bbl is larger/largest. It kind of sucks that getting this info from Carter is, well for me at least, a mystery. Holley will tell you everything about there carbs.

 

[318willrun]

Get one off a 383.

I’m not sure at all of the various sizes though I’m sure a 440/400 2bbl is larger/largest. It kind of sucks that getting this info from Carter is, well for me at least, a mystery. Holley will tell you everything about there carbs.

Has to be from a 318. Or a super six.

 

[RustyRatRod]

Has to be from a 318. Or a super six.

Says who?

 

[318willrun]

Says who?

It's obvious I know how easy it is to throw on a 4bbl, or a 360 intake and a 400 2bbl, or a 500 cfm Holley.... we've both been around the block more than once. So lets go back to the first post:
"I wondered if anyone flowed a 2bbl BBD from a 318? And ways to improve flow?? Size of the venturi for possibilities ???

Thanks for any experiences you wish to share."

This is the specific info I am enquiring.

 

[RustyRatRod]

It's obvious I know how easy it is to throw on a 4bbl, or a 360 intake and a 400 2bbl, or a 500 cfm Holley.... we've both been around the block more than once. So lets go back to the first post:
"I wondered if anyone flowed a 2bbl BBD from a 318? And ways to improve flow?? Size of the venturi for possibilities ???

Thanks for any experiences you wish to share."

This is the specific info I am enquiring.

ok. Have at it.

 

[318willrun]

Years of main body that would have the largest venturi ???? I have held, seen, and owned some with larger/smaller venturi's. I have no remembrance of what years or what they came off of, other than 318's.

 

[rumblefish360]

Subscribed to see what comes of this inquiry.

 

[Jax_1975_Dart]

I’m following this, too. Getting ready to convert to a Super Six, and would LOVE to know if there are any experiences with different venturis on the same Carter BBD 2 bbl.

 

[318willrun]

Subscribed to see what comes of this inquiry.

I’m following this, too. Getting ready to convert to a Super Six, and would LOVE to know if there are any experiences with different venturis on the same Carter BBD 2 bbl.

It's been a while, but while doing a super six /cut head .100 in a Duster we found by going through a few 318 2bbl's that the venturi size was really ranging in sizes. It was a notable kick in the git-go of the car as well. Though the butterflies may look the same size, and they are rated the same, I can tell you there is a quite a difference between some of these. It could be one of the reasons why one Duster with a 318 2bbl gets the best of another though all else is the same. Also, what else can be done to "aid" in the flow. Remove the choke assembly?? hone-polish the venturi ???

 

[rumblefish360]

I’ve done both. The choke is good for a few cfm’ wot noticeable power. IDK how much or well polishing does.
Taking a dremal (sp?) and doing some minor work on the booster and anywhere else you can stream line air flow is a plus as well.

 

[Bewy]

With such a small carb, thinning out the t/shaft, removing the choke, polishing sharp edges etc should give a significant increase in flow.
D. Vizard recommends making the bottom edge of the booster venturi sharp, it improves signal delivery.

 

[RustyRatRod]

With such a small carb, thinning out the t/shaft, removing the choke, polishing sharp edges etc should give a significant increase in flow.
D. Vizard recommends making the bottom edge of the booster venturi sharp, it improves signal delivery.

Funny how that works. They also knife edge the trailing edge of crankshafts in big time racing applications. Same principle, I suppose.

 

[mod5v]

Is low speed drivability important? Anyhow back in the late 80's we had to run a certain rochester 2bbl on our dirt cars but you could do anything you wanted to it. It just had to retain factory appearance externally. There were guys boring the houseing out and installing bigger butterflys, removeing as much material as posible from the ventries, thininig down the throttle shaft ,etc,etc.... some of them things probably flowed 6-700cfm and ran real good above 3000rpm..

 

[halfafish]

Size of the venturi for possibilities ???

I can't help with the flow question, but over time I have somehow acquired a small herd of BBD carbs. I can get you venturi measurements and carb numbers if that will aid your quest. I have no idea what vehicles these things came off of. LMK.

 

[318willrun]

I can't help with the flow question, but over time I have somehow acquired a small herd of BBD carbs. I can get you venturi measurements and carb numbers if that will aid your quest. I have no idea what vehicles these things came off of. LMK.

Only if you have time... thanks! Most that I've seen, the difference can be seen by eye, however, I have never measured them. A true measurement would be awesome!

 

[318willrun]

With such a small carb, thinning out the t/shaft, removing the choke, polishing sharp edges etc should give a significant increase in flow.
D. Vizard recommends making the bottom edge of the booster venturi sharp, it improves signal delivery.

Awesome!

 

[318willrun]

Is low speed drivability important? Anyhow back in the late 80's we had to run a certain rochester 2bbl on our dirt cars but you could do anything you wanted to it. It just had to retain factory appearance externally. There were guys boring the houseing out and installing bigger butterflys, removeing as much material as posible from the ventries, thininig down the throttle shaft ,etc,etc.... some of them things probably flowed 6-700cfm and ran real good above 3000rpm..

Yes, driving quality at low RPM/Idle is important!