Dual carb advantage?

[[email protected]]

What is the advantage of a dual carb setup on my 8BA I have in my 37 pickup? I once installed one on my 46 2door sedan and even with the correct power valves did not see much difference. What would be the best setup? I did install a T-5 AND REALLY LOVE IT but still have a small vibration between 51 and59 mph. Before and after there is none. I always appreciate the wealth of knowledge and help I recieve. Thank you, Jim in Orrington Maine.

[tubman]

On a street-driven car, I am partial to a small base Rochester 2G on a bored out Mercury manifold. Mounted backwards, the carburetor will bolt right to the manifold and the fuel line and throttle linkage fall right into place. The choke is a different matter; it operates backwards. Since the Merc manifolds have a provision for automatic chokes, I have used the automatic choke 2G's (both regular and divorced) with no problem. The only problem is that there is a leverage problem and, while the throttle linkage falls right into place, the a stock Ford throttle linkage only opens the carburetor about 3/4 of the way. Either the lever on the firewall or the one on the throttle shaft need to be modified to get full throttle. These carburetors flow about as much as 2 94's, so you essentially have the increased carburetion that 2 regular carbs provide, but with the simplicity of a single unit. I have been running one of these on the '51 Merc in my '51 coupe for the last 3 years and am very satisfied with the driveability and performance.

Of course, this is fine if you have a car with a hood; for anything else, you gotta have the dual setup.

[JSeery]

Two carbs are going to flow more air than a single carb. This is not going to make much difference on a fairly stock engine that doesn't see much high RPM usage.

[Ol' Ron]

Add some 2" risers under the carbs

[Ronnieroadster]

Got to a four barrel it will work much better is easier to stay in tune and another benefit you will get better fuel economy.
Ronnieroadster

[petehoovie]

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"What would be the best setup?" - Retain the original factory carb setup....

[[email protected]]

Thank you very much. I'll see if I can find a Merc, manifold. Ya'll came through again.

[AnthonyG]

The best set up to a large degree is based on ur engine & what ur looking for. If ur engine is perfed up w oversized valves & a 3/4 or higher cam one 2 barrel will only achieve 70% of the engine potential. U’ll Get much better pedal response than stock but wont realize what the engine acceleration potential is. As far as wether 2-2’s or a 4 barrel is better as said the 4 barrel is easier to keep in tune but the 2-2’s especially w a sling shot or hi-risers or both looks way cooler in an old school way!

[frnkeore]

There are many different CFM rating for the Rochester 2G/GC. They range from 225 to 500 cfm. From what I've found, the 2 basic sizes (1 1/4 & 1 3/8 Venturi) are usually rated at 285 & 450/500.

I believe the "94" is ~125 and the 2100 version, 150 to 155 cfm.

So, the smaller 2G is about the rate of 2 94's and the larger one, three 94's.

I have both a Merc manifold and one of the small 2G's for sale. $100 plus shipping.

[Ol' Ron]

That's avery good price, especially if the intak is bored out to the 2GC throttle size. As forr the large 2GC it won't bolt to the merc intake. However the small 2GC base will fit the mid size carb. Might work, haven't tried it yet.

[frnkeore]

I have at least 3 small 2GC's and at least two large ones.

The price, does not include opening the manifold but, I can do that for a additional $30.

This is the manifold.

[oldskool]

speedway sells a 3 bolt to 4 bolt carb adaptor

[[email protected]]

Thank you for the help. How about boring out the stock manifold? Why the Merc?

[blucar]

It has already been pointed out that multiple carbs on a stock engine will not produce any benefits, other than bragging rights.
If you change the cam and ignition and run the engine at high rpms, like street racing you will experience good performance, however, for every day driving a 4 barrel carb will be more trouble free.

[Tim Ayers]

Originally Posted by [email protected]

Thank you for the help. How about boring out the stock manifold? Why the Merc?

It's easier to find a 4 bolt 2GC vs. a 3 bolt. Merc. intake is a 4 bolt.

[JWL]

If you read my book you will see there is more usable street performance available in the dual carbs or 4 barrel than any cam change will provide.

[Ol' Ron]

The bennafet you get from jWLs book is: it saves you money bt answering questions you didn't ask. He takes the stock block from 80 hp factory stock to just under 100. without going into it. Then he does.

[[email protected]]

Thank you. I found the book nearby. I have some reading to do. I like the idea of a 4bbl. Now to find one affordable. LL.

[philipswanson]

Originally Posted by JWL

If you read my book you will see there is more usable street performance available in the dual carbs or 4 barrel than any cam change will provide.

What's the title and/or ISBN of the book. I'll pick up a copy.

[Ronnieroadster]

Originally Posted by [email protected]

Thank you. I found the book nearby. I have some reading to do. I like the idea of a 4bbl. Now to find one affordable. LL.

Since both Edelbrock and Offy four barrel intakes are still being made new check what Speedway Motors is getting for them which i think is the best price going. For a good carb when i help others with similar combinations i simply use a good Holley 600 CFM carb. What ever you don't waste your time and money on the 390 CFM Holley four barrel the performance sucks using that to small of a carb. Replaced many of those little 390 carbs with the 600.
Ronnieroadster

[[email protected]]

FRNKEORE send me an email at [email protected] Please.

[tubman]

You should be aware that the 4 BBL manifolds from Offenhauser and Edelbrock (as well as the one Speedway sells under it's own label) have what is known as the "square bore" carburetor bolt pattern. As such, they all need an adapter to use a Holley or Edelbrock. There are many carburetion experts who view any kind of carb adapter as inefficient.

I like the look of older "square bore" 4 BBL's (WCFB's and early Rochester 4G's) on these engines over the new Holley's and Edelbrocks. However, decent cores are almost impossible to find and expensive if you do.

This was not the case 10 years ago.

[chap52]

Benefits...Looks Cool... Chap

[JSeery]

Originally Posted by philipswanson

What's the title and/or ISBN of the book. I'll pick up a copy.

Flathead Facts by John W Lawson.

[[email protected]]

Thank you all. FRNKEORE was great talking on the phone and great tips. I will put it up n the rack and run it and check to see where the vibes come from. Also will check on the bigger carb with a 4 bolt conversion. You guys are wonderful. Jim.

[frnkeore]

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It was very enjoyable, talking to you, Jim.

[Ol' Ron]

You can get Johns book at Max VP, He also had many parts for the engines and transmissions.

[Talkwrench]

I'd go for more wan... show factor, I drive with twin 97's on a slingshot everyday. with mine it takes a while for it to heat up and run well, meaning I have to keep the choke on longer. In traffic the single carb is probably faster too. But whats surprising is that I can get 22Hg with the twins [at sea level, idle just over 600 rpm] not bad for a flathead...

[Bored&Stroked]

Originally Posted by Talkwrench

But whats surprising is that I can get 22Hg with the twins [at sea level, idle just over 600 rpm] not bad for a flathead...

Yeah, but that is because you guys are upside down and your sea level is a lot lower than ours . . . causing much better vacuum to be generated.

Just kidding yah!

I hope to get back to OZ soon - I only wish I could bring one of my HotRods over to drive from the Gold Coast back to Sydney. I've had some wonderful times on that route!

[Talkwrench]

Ohhh its global warming..
You'll have to try the west coast next time!

[Tinker]

If you are not going for max acceleration and just want to drive. You could probably get around 22mpg on a single carb. 4 barrel being the in-between. It was in the 70s and big blocks gas wasn't a concern. Well...


Most of us don't drive these everyday. I'd have a gasser to get groceries once a month in a perfect world.



.

[[email protected]]

Had a 53 Mercury manifold complete with carb, fan 4 blade and fuel pump. Is this T-pot carb any good and would it perform like a Rochester 2g? What is the CFM?

[[email protected]]

Given to me . FREE.

[tubman]

They're all right, I guess. They are a bit smaller than the small base Rochesters, and parts and kits are harder to find and pricier. On the other hand, you don't have to bore the manifold out for them to perform at top efficiency. They are Holley 885's. I would check with some of the carb guys (Charlie ny, scicala, Uncle Max) and see if they will rebuild them and how much.

The price is certainly right.

[[email protected]]

which 2bbl would give me the best performance with the Merc manifold?

[tubman]

I have never run a Merc carb (885), but I would expect that the Rochester (being a larger, more modern carb) would yield better performance. You might also want to consider a Holley 2110 3 bolt version, as they are larger than a stock 94. The 2G flows more than the 2110. Both of these choices would require enlarging the manifold throttle bores. When I do a Mercury manifold for a 2G, I use a "Rota-Broach" that will bore them out all the way down to the floor of the manifold. I then use a die grinder to blend the edges. It's probably overkill, but it's kinda fun!

[[email protected]]

FOUND THE VIBRATION. It was an incorrectly built and installed rear transmission mount. George Sprowl of Antique Express in Searsmont Maine found it and fabricated a correct mount and installed it. Miracle worker for sure.
Thank you George