Basic Flathead multi carb intake and carb identification

Basic Flathead multi carb intake and carb identification

There seems to be more and more people getting interested in traditional Hot Rods and Flathead engines. I thought it would be good to write quick guide to identifying what is what.

Firstly Production of the flathead started in 1932 and went through to 1954 in Australia and Canada 1953 in the US. Over the course of those 22 years there are 3 main changes in the engines. Firstly from 1932-1937 is the 21 stud motor. So named because there are 21 studs with nuts holding each head down. Then there is the ‚Äòearly‚Äô 24 stud motor that ran from 1938-1948. Then there is the 1949-1954 which rightly or wrongly are referred to generically as the 8BA

For the person who wants to build a hot rod with a flathead but doesn‚Äôt know much about these motors this will give you a basic guide so you will have some understanding as to what your looking at. But the best bet is to shell out some money and buy some books to read.

The first identifying factor is of course the head studs this will tell you if it‚Äôs a 21 or 24 stud motor. For the general run of the mill hot rod motor you are best to stick to the 24 stud motors. As parts availability, particularly for hotrod bits for these is far greater.

Now with the 24 stud motors the easiest way to tell the difference is with the heads and the distributor. The early 24 stud motor has the waterneck cast into the head and is positioned in the centre of the head.

The 8BA motors have a bolt on water neck outlet and it is postioned at the top and front of the heads.

The distributors on the early 24 stud motors are mounted at the front centre of the motor in between the water pumps and is referred to as a ‚Äòcrab style‚Äô distributor due to the 8 leads exiting the cap I guess looking like crabs legs. the earlier distributors were refered to as ‚Äòdivers helmet‚Äô . With the 8BA motors the dizzy is a more common ‚Äòpost‚Äô style if you are standing at the front of the motor it mounts on the left hand side at the front of the block through the timing cover. The other tell tale sign is the bellhousing. With the early 24 stud motors, they have a half bellhousing cast onto the block. While the 8BA‚Äôs .are like the more modern OHV motors. With a bolt on bellhousing.

These basic points will help you out in figuring out the basics of which engine you are looking at. HOWEVER. Just to confuse you , with some slight modifications early heads and distributors can be mounted to the 8BA motors. But that can be covered at another point in time. Also don‚Äôt forget that with the passage of time, that old motor could have been rebuilt a few times and in the need to save money god knows what could have been cobbled together to get it running again. So pay close attention for more than one tell tale sign.

INTAKES

As the flathead was around for 20+ years there were more intakes made for this motor than I care to think. The motor its self evolved in that time, however for some reason the bolt down position for the intake never did. So for that reason alone with some slight modifications you can bolt an intake from a 1932 motor onto a 1954 motor and vice a versa. This quick guide will allow you to tell the basic differences in the aftermarket multi carb intakes.

The multicarb intakes it seems didn‚Äôt take long to show up on the market for the new V8‚Äôs as hot rodders knew that there was horsepower to be had with the new motors and experience told them from their four bangers that multiple carburetion would increase that stock hp figure. The main multi set up intakes are the 2x2 and 3x2. there was 4x2 intakes made, however they were mostly for all out racing. As with the motors , there are subtle differences with the intakes.

2x2
With the 2x2 there are 2 basic styles. That is either the ‚Äòregular‚Äô dual or the ‚Äòsuper‚Äô dual. The main difference with these is the positioning of the carburetors

The regular dual is at the top, the super at the bottom. you can see clearly the difference in spacing for the carbs. You can also see that the Regular dual ( edmunds) has provision for the generator mounting bracket where the also early super intake doesnt.

The ‚Äòregular‚Äô dual has the first carburetor in pretty much the stock location with the second carb placed behind it. The reason for this was to allow for the generator to be run in the stock location. This was of course the cheapest of ‚Äòhop up‚Äô ways to go, as it required the minimal amount of alteration to the car. This was more the street intake. Carb spacing is generally 4 ¬æ‚Äù but can be more.

The ‚Äòsuper‚Äô dual has the carbs spread wide apart and placed directly over the ports to allow for quicker fuel entry into the combustion chamber. This was considered to be more a race intake. This of course also meant that the generator had to be moved to another position, which added to the cost as an ‚Äòoffset‚Äô generator bracket was then also required.

Here are three super duals, each is slightly different the bottom right is a weiand, firstly it is a dual plane design as can be seen by the runners that wind from opposite sides of the intake. Secondly it has the heat risers that is the sort of triangle shaped raised section that is between both carb pads down where the intake bolts onto the block. This is meant to allow heat from the exhausts to rise up and warm the air fuel mixture. There is mixed feelings on the benefits of this. This is evident as the other two intakes do not have this. the top right is a BEP from Australia it is a 'log' design as both carbs open into a big open area for the air fuel to mix, there is no direction for the air fuel mixture unlike the dual plane, it drops into a big area like a hollow 'log' Intakes like this are usually found on racing engines. but can work on the street. They are not renown for their low down drivability. The 3rd intake on the left is a 'Lundberg and Son' this is a race intake as both carbs are spaced 'super dual' pattern however each carb is positioned dirrectly above the blocks runners. Both these last intake are more competition. The Lundberg and Son's was mostly known in the boat racing circles.

Of course to add to this there is variations in the intakes depending on if they were to suit the early or 8ba motors.

The main differences are in the location of the oil filler and the breather. With the early motors, the oil filler and breather is part of the fuel pump stand at the back of the intake. With the 8BA there are two machined areas on the right hand side ( standing at the front of the motor) of the intake, one is for the oil filler the other for the road draft tube. Also the early motors had dowls to locate the intake, these didn‚Äôt appear in the later intakes.

3x2

With the 3x2 intakes the two biggest things to watch are if they have the mounting area at the front of the intake for an offset generator bracket and if the carburetor spacing is for Stromberg 97‚Äôs only or both Strombergs and Holleys. The reason being that some of the early 3x2 intakes carburetor mounting spacings is soley for Strombergs

Early vs late intake. in the forground is an early weiand 3x2 this can only take stromberg 97's not it is also missing the generator mounting bracket locator at the front, so made for an offset generator bracket that bolts onto the head.The back is a new Sharp 3x2 late intake for the 8BA motor. It has both the hole for the road draft tube and the oil filler.if you want to use the late intake on an early motor you just need to block these holes. some welsh/freeze plugs from the auto store will do the trick, just also use some silicone to make sure they are sealed. This also has the generator mounting pad for the late off set generator to mount to.

Fitting the early intake to the late motor

There is a little bit required to do this, but it is not beyond most. The early look intake is my personal preference for use on any year motor, as without the oil filler and road draft tube the use of the early intake makes the front of the motor look cleaner. As discussed, the bolt pattern is the same, the main issue arises in allowing the motor to breath. This can be achieved by the use of the early 24 stud fuel pump stand that incorporates the oil filler/breather. However if your still running the mechanical fuel pump, then the push rod needs to be shortened to suit. If your using an electric fuel pump then this is not an issue. And any breather set up can be used to suit your application. There are aftermarket ones made soley for this purpose. There was some variation in the generator mount on early intakes, and if you had an original period intake you might need to bolt the generator up to it to check for alignment of your fan belts. I have found that a bit of plate as a packer will solve this problem quickly and easily. The only other thing is in the 8BA valley there is a tube that rises up from the oil pan, this sits proud of the intake deck and you will find your early intake wont bolt down. This is a stamped steel cylinder and can easily be removed with a pair of pliers, as with the breather at the rear of the intake it is not required anymore.

If your using a super dual on the 8BA motor and cant mount the generator in the standard location you may need to use an offset generator bracket. There are two types , the early 24 stud piece that bolts onto the head or the 8BA style that looks like a Y shape these both come in either passenger side or drivers side.. I have found on 8BA motors that you can use the early offset bracket on the head by the use of three ¬æ‚Äù tube spacers and 3 pieces of 7/16 all thread to replace the head bolts and act like extended studs. The spacers get the bracket up and clear of the water neck of the 8BA but otherwise allow the bracket to mount as it would with the early 24 stud head. This gives that lovely early look with the generator hanging out to one side while letting it clear all vital components.

early offset generator bracket

showing that it does line up with the 8BA holes

97 vs 94

For the new to Flatheads person this can be a tricky issue initially. There are many variants of each carburetor I have heard that there are over 30 variants of the holley 94. the quickest way to tell the difference ( besides the name being cast on most , on the side) Is the location of the fuel inlet. The Strombergs have the fuel inlet on the side of the fuel bowl ( centre part of the carburetor) and the holleys have the fuel inlet on top as part of the air horn.