Many inline enthusiast use aftermarket Carb adaptors to install a two barrel carb to the integral log intake, replacing the anemic one barrel. There are many different types of adaptors, so you'll need to make sure you purchase the correct adaptor for your application and choice of carburetor. Most of the adaptors offered are for Weber carbs, however there are those that allow Holley and/or Autolite 2V carbs to be adapted to the log intake. The most widely known adaptor, From Offenhauser, allows the use of triple one barrel carbs.

While the adaptors seem straight forward, they are not. Not only do you need to make sure you purchase the correct adaptor, there are other issues you need to consider. Some adaptors require a spacer, which is used to square the carb orientation (making it perpendicular) to the crankshaft. While the spacers are not absolutely required, the end result without a spacer, will result in a misaligned carburetor as seen in the picture below.

Stacking up adaptors and spacers may result in inadequate hood clearance as well. To compensate, you must use drop base air cleaners with narrow elements, or a carb hat with a remote air filter. In most cases you will need to switch to a throttle cable as well, which needs to be custom fabricated for your application as no kits currently exist.

Upgrading to a two barrel carb over the one barrel definitely offers improved performance. However, the increased air flow is funneled into the integral log intake through the existing one barrel opening, thus limiting the full potential of a two barrel carburetor. For more info see the dyno results we got when we tested three 2V carbs mounted via an adaptor.

Another method of upgrading to a 2V carburetor has become popular amongst the FordSix Performance forum members. This method incorporates mounting a custom adaptor to the log and hogging out the carb opening. Depending on the design of the adaptor, this method allows the use of the popular Holley and Autolite carburetors, which offers better hood clearance and substantial increases in power and torque (dyno test forthcoming).

The only drawback to this method, is that the intake needs to be milled flat, which requires removing the cylinder head for machining. Prior to milling, the low spots on the intake manifold need to be built up, which is accomplished by furnace brazing. Once the brazing and milling have been completed the cylinder head should be milled. This not only true's the head surface, it is also done to achieve the correct chamber volume and compression ratio. In most cases, the stock compression ratio is raised to 9.0 or 9.5 to one. A three angle valve job is also recommended.

To mount the two barrel carb, you'll need a custom carb adaptor. 2V Conversion Adaptors can be purchased from Classic Inlines, or you can have any competent machine shop make one for you. Depending on the design and complexity of the adaptor, a spacer may (or may not) be required. The adaptor is mounted to the log intake by drilling and tapping three or four holes. You can use gaskets, high temp silicone, or JB Weld to seal the adaptor plate to the intake. Many use JB Weld to assist in keeping the adaptor tightly seated and sealed to the log intake, however it may develop hairline cracks over time.

Regardless how you go about it, this is probably one of the best performance mods you can make, short of purchasing an OZ250-2V cast iron head, or the new aluminum head. It's worth the extra effort and cash, so if you have the time and money, don't hesitate making the decision. You won't regret it. For a side by side comparison, check out our dyno results.

milled intake

custom adaptor mounted

custom adaptor mounted

custom adaptor mounted

here, a spacer was used between the adaptor and the carb

carb mounted and plumbed

throttle cable hooked up

completed installation with carb hat

clean and simple, yet very effective