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Re: 1bbl to 2bbl
#63785 Thu Aug 03 2006 08:02 AM
Joined: Jul 2006
Posts: 58
2
Member
I've spoken with Mr. Langdon on the subject. I originally was going to get the Carter/Weber when I found out that it's original application was for a 1983 Ford 4cyl and not meant for 6ers (Carb too small). I did not go with his Holley because by then I had ordered the adapter, an adapter that does not fit the Holley.

I am looking mostly for response, and I will later add headers. Not looking to rebuild the block insides or head. I also am considering a 700R4..... but that's an entirely different story.

CARBKING:
This adapter is about an inch and some change tall. Why would height matter? Is the taper from 2bbl to 1bbl to extreme for proper fuel flow or something like? I figure that it's all going down the same hole, you're just shoving more down there with a more efficient device.


1967 Chevy truck "The Hurricane"

WARNING:
This suspect has a tendency to jerry-rig.

"My engine ain't fast, but I pulled a tree trunk out of the ground once."
Re: 1bbl to 2bbl
#63786 Thu Aug 03 2006 11:04 AM
Joined: Jan 2000
Posts: 1,609
T
Extreme Gabster
I tried that very adapter and a Rochester 2bbl once,it really didn't improve the performance and the adapter caused mixture issues at wide open throttle.Of course your results may differ.
What did work well for me,I cut open the original carb opening on the intake,reprofiled it to match the two barrel I was using.My grinding got into the double wall area of the heat riser section,some work with a Mig welder was necessary.I then made an adapter plate from one inch thick phenolic material,bolted it to the modified intake after drilling and tapping some holes.Made up a linkage cross over to utilize the stock gas pedal set up. Wasn't all that difficult to do really.
This set up works very well on a 261 engine,gave more power,better throttle response and actually a few MPG too.I didn't use a Rochester carb,but any two barrel should be ok.

Re: 1bbl to 2bbl
#63787 Thu Aug 03 2006 01:29 PM
Joined: Nov 2002
Posts: 2,067
C
Carburetion specialist
250supersix - as to why the shorter adapter does not work as well, I can only speculate; but my guess would be turbulence.

Take a look at Tony's post right below yours.

When we were doing our testing, comparing a GOOD 1 barrel against the two barrel and adapter, we were unable to obtain the same fuel economy or power unless the adapter was shaped, and at least 6 inches tall. However, comparing the 2 barrel and adapter against a warped Rochester B, the 2 barrel and adapter would be better.

For the "do it yourselfer"; a good way to go is to fabricate a new manifold using aluminum with a plenum to match the two barrel of your choice. This can easily be done by using flat aluminum stock for the piece fitting the head, and various tubes and elbows of electrical conduit (from the electrical supply shop). Lay it out and heliarc weld the unit together. The carburetor flange can be made by acquiring one of the newer aluminum adapters, and cutting it to fit.

Of course, if a four barrel manifold can be found, a Carter 400 CFM AFB (9400s or 9410s) will work extremely well (albeit at more initial cost).

I put over 500,000 miles on a different vendors 6 cylinder (400,000 after installing a Carter 4 barrel). This was a 300 CID engine in an extended wheelbase van. At 70 MPH highway, the van averaged 22 MPG, and I have witnesses to this fact. Power was significantly improved over the original single barrel as well. I used an Offenhauser manifold for this project.

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: 1bbl to 2bbl
#63788 Fri Aug 04 2006 12:09 PM
Joined: Jan 2000
Posts: 1,609
T
Extreme Gabster
Carbking's points are very true,in my opinion,the Rochester B carb is a crude device and any other similar sized one barrel is bound to make a noticable improvement in general improvemnet.
On several of my 235's ,I threw away the Rochesters,and replaced it with a Holley 1900 from the 60's Mopar slant 6's.Not that the Holley one barrel is the best unit,but I have a few layin around.It took a little fiddling with linkage and such,but the end result was better response and fuel mileage.And the engines actually ran smoother at all speeds.
I believe Carbking says a Carter YF pretty much bolts on and offers good results.
The single Holley-Weber works ok,but Langdon himself has said the small primary throttle bore may reduce part throttle power especially on a heavier vehicle.And ya still have the suspect adapter issue.
Anyways,here's a photo of a 2300 Holley two barrel on my homemade adapter on the modified stock manifold,261 engine.Again,I used a Holley cause I have them here,any brand 2 bbl off a small 8 should be just fine.It's a clean installation,I even reworked the stock oil bath aircleaner to fit.This carb is a 300 cfm unit as found on the small IHC V-8's,I didn't change jets,the stock choke cable hooked right up.It's been great for several years,way better performance than the one barrel and more MPG's
Carb swap

Re: 1bbl to 2bbl
#63789 Fri Aug 04 2006 02:18 PM
Joined: Feb 2000
Posts: 4,175
J
Shop Shark
250supersix, your idea of shoving more down the same hole is incorrect! The fuel is sucked down from the engine, it doesn't matter how big of carb you put on, only so much is going to go down the small intake hole! The tall height has to do with air flow and resistance. Joe

Re: 1bbl to 2bbl
#63790 Fri Aug 04 2006 03:26 PM
Joined: Mar 2004
Posts: 745
M
Shop Shark
I tried several different 2G's on my 292. I installed an Offy 4 bbl intake and then an adapter for 2 bbl. Seems like I tried 3 or 4 different ones and never could get any of them to work. Each one had its own problem. No ported vacuum, hard to get timing right, idle issues, mixture never right even setting with vacuum gauge, response fine with steady pedal but bogged otherwise.
I installed a small 4 bbl. I've been driving it ever since and that was over 2 years ago. Either do like Tony did and forget about that adapter or get yourself an Offy 4 bbl intake (got mine used on ebay for $125) and install a small Holley or Carter. It's worth the money.
-David


Tradin' up dimes for nickels...
'`'`'`'`'`'`
My \'65 Chevy C-20
Re: 1bbl to 2bbl
#63791 Sat Aug 05 2006 06:02 AM
Joined: Jul 2006
Posts: 58
2
Member
And putting a 4 BARREL on a small 250 inline 6 would be th same as shoving mroe fuel into the motor? Sure, you now have 4 holes to choose from, but it's all still going to the same place. As far as I'm concerned, the 2bbl is still going on. I've devised a plan to set up ncie linkage using 2 bellcranks and the timing just takes... time. Even if I don't achieve better performance, anything is better then the ancient piece of crap I have right now.

Look, I love these forums, so don't get the wrong idea. I respect all of your opinions and am not typing this with any sort of negativity.

But, stacking a 4bbl on a little inline 6 is just about the most outlandish thing I've heard of! If you completely rebuilt the motor from top to toe and added all performance parts, then maybe she could handle the stress. But mark my words, those of you that cut corners while putting on a 4 barrel will end up with a whole laundry list of troubles.

In closing, I'll atleast end up with a carburetor that doesn't get me stuck on the on-ramp (a prime example of my current issues).


1967 Chevy truck "The Hurricane"

WARNING:
This suspect has a tendency to jerry-rig.

"My engine ain't fast, but I pulled a tree trunk out of the ground once."
Re: 1bbl to 2bbl
#63792 Sat Aug 05 2006 06:23 AM
Joined: Jul 2006
Posts: 58
2
Member
Another thing, too, why would an adapter like this be built if it wouldn't make a lickin' difference?


1967 Chevy truck "The Hurricane"

WARNING:
This suspect has a tendency to jerry-rig.

"My engine ain't fast, but I pulled a tree trunk out of the ground once."
Re: 1bbl to 2bbl
#63793 Sat Aug 05 2006 01:56 PM
Joined: Jan 2001
Posts: 667
C
Shop Shark
Because somebody will buy it.

Re: 1bbl to 2bbl
#63794 Sat Aug 05 2006 08:02 PM
Joined: Jul 2006
Posts: 32
O
Junior Member
250supersix, The whole idea of a 4 barrel carb is that it is progressive in opening most of the time it operates like a two barrel but at WOT the back barrels open allowing max air/fuel mixture.

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