When dealing with most of the above carb setups several handy resources are very useful.

1. How To Build & Power Tune SU Carburettors by Des Hammill
2. Haynes Teckbook Weber Carburetor Manual by A K Legg, Don Peers, Robert Maddox & John Hayes
3. Web Based Comparison SU Needle Guide - FREE
4. WINSU Software - cost
5. Set of small screw drivers
6. Set of small screw drivers

Available Carb Options

The Zenith Stromberg Carb Setup

The Zenith Stromberg Carb: is a fine carb but many dislike it for various reasons. Personally I found it just fine except for one major problem, I could never resolve the water choke assembly problem from leaking gas. Eventually I tired of the problem after trying 3 different ZS carbs. Looking back I could have added a manual choke. You would need to parts to do this. A great article to read however is the following. It gives great detail in how to rebuild the Zenith Stromberg and is often referred to by many. testArticle on the Zenith Stromberg Carb."  Another piece of information I've read in the midget Forums is that "Starter Fluid Spray", sprayed into the carb tends to deteriorate the diagram quickly and you may almost immediately find that you will have to replace it..

Good video on U Tube showing some repair work on Stromberg

SU Carbs

Rebuilding SU Carbs: U Tube

The HIF-6 Single SU Carb Setup

Following my decision to convert to something different then the Zenith Stromberg Carb I ran across a deal I couldn't pass up. A SU HIF-6 with a manifold that fit the 1500. Cost $50. In hind sight would I do it again. Probably not as there isn't much information out there on using the HIF-6 on the 1500 and I was never able to get any other on forums, etc to share the actual Needle/Spring setup they used. So its a mixed of educational guesses and research for what information is out there. I was able to get the carb setup to run ok but not near what I thought was close to a near balance of power and performance I think is possible given time, money and research. Again there are some out there saying they are using it without problems but don't seem to want to share much about it. For details click on this link to get my experience with the HIF-6 setup.

For more information go to the 1500 modification web page by Clicking Here

General Information & Design of the HIF-6 SU Carb

Benefits of the HIF vs the older H and HS model

The Integral float = the 'IF' in the new type number HIF. The previous H and HS type carbs with their side-mounted remote float bowls worked fine until used in racing where serious cornering speeds generated enough G-forces to lean-out the fuel mixture. The remedy was to fit a spacer between the float lid and float bowl to raise the fuel level held in it. OK when running, but at idle and rest, fuel would bubble out of the jet - causing bore washing, poor pick-up, and horrendously rich CO mixtures at idle! Fitting the float integral with the carb, directly below the jet hole (port/orifice), eliminated this problem.

Jet temperature compensation - This was first aired on HS types, and was known as the 'Wax-stat' type. To keep in line with emission control legislation and the need to improve fuel consumption figures, a device was needed to lean the fuel mixture off as fuel temperatures went up. Unfortunately the Wax-stat wasn't very efficient, and increased the likelihood of bending the already vulnerable jet further. The HIF type uses a bi-metal blade to raise and lower the jet as needed - it's construction and location making it a far superior design. Its technical application label is 'viscosity compensator'. This close control means that once correct fueling is established by needle selection, the mixture is maintained over a very wide operating temperature range. Consequently drivability is enhanced and emissions are kept within tighter limits during cold starting and warm-up period.

Cold-start enrichment - HS types used a cable-operated lever that both lowered the jet (gave a greater hole to needle profile ratio to allow greater fuel flow) and opened the butterfly slightly (necessary to prevent low speed stalling with over-rich mixture). Messy and not very well calibrated. Enrichment in the HIF is supplied by means of a separate fuel-path within the carb body between float chamber and constant depression area close to the jet hole. A rotary valve - effectively a long, plain-shanked screw with a slot in it, controls metering. Earlier example used a 'V' shaped groove, changed on the very latest ones to a rectangular groove to achieve better control through more accurate machining when manufactured - a feature that none of us would notice!

Ball bearing suction chambers - A plastic sleeve containing two rows of six small ball bearings were introduced to reduce friction to the absolute minimum in the piston/suction disc/damper rod assembly. The benefit is simply more rapid response to varying demands caused by opening/closing throttle positions. Again in an effort to provide ever closer fueling control.

CONS Vac pipe take-off: There's always something to spoil the party! On some HIF carbs, the vac take-off sighted just after the butterfly - that's between the butterfly and the carb to manifold mounting flange - has been eliminated. Instead, the engines these carbs are fitted to use a vac take off in the manifold. The reason for this is again wholly idle emissions orientated. The higher vacuum that exists in the manifold area can be used to pull more advance. Theoretically this will reduce emissions at idle. Unfortunately it's exposed to induction pulsing. In the A-series, this is UGLY. The pulsing and high manifold vacuum causes rough idling. Particularly where anything 'sportier' (ANYTHING) than a bog-stock-standard cam profile is used.

1. Port Descriptions
2. FUEL INLET PORT
3. FLOAT CHAMBER OVERFLOW/BREATHER
4. CRANKCASE BREATHER PIPE CONNECTION
5. FUEL MIXTURE ADJUSTMENT

Most needles have the same point diameters at #1 & #2 and for all practical purposes #2 is where idle occurs. Needles are typically 0.001in smaller than the main jet diameter. For one to get the car started so further refinements can be made. But how does one determine where to begin. For me exploring the listing in the Haynes Teckbook Weber Carburetor Manual for similar sized engines running a HIF-6 or HS-6 was helpful. There weren't many listed so I had to add the HS-6 as well, which is simple an older model but is the same size. I also spoke with Joe Curto who recommended the "BEL" to start with. The realization may come that a pre-fabricated needle just won't meet the needs of a modified engine. If that is the case one will have to modify the needle by carefully filing it. I recommended reading "How To Build & Power Tune SU Carburetors by Des Hammill" The power tuning book is actually an easy read. Take the time to read it prior to making the change to see if you are up to making the change. It will guide you through that process. One interesting finding has been that as I have asked for what size needle 1500cc midget users who have converted to a HIF-6 setup on Forums I have yet to get a reply to my inquiries. This makes me think few have had success in this conversion.

Below is a selection list I found in the Hayes Appendix for SU Carbs:

Bottom line is its a matter of doing a lot of hunting around trying to select the best needle combo. The above gives you an approximate idea of which needles to start with and one comes to a conclusion that you end up in a ballpark area and will then have to perhaps do some customizing to get maxim performance.

The needle I was going to try was the "BAS" with a Red Spring. This is one of the needles listed above and is considerable more rich then the "BEL", that Joe Curto had suggested trying. The "BEL" I had problems with from the very start. I had to jet it to the max to get it to even idle. I did recently get a message from a user who told me he is running the "BCE" and that he gets pretty good performance. In fact by order of lean to richer it goes: The "BEL", then "BAS", then BAL and finally the "BCE". I really have had little to compare a well running midget to since I went from a stromberg with problems to the HIF-6 setup until just recently when I decided to purchase a dual HS4 setup and converted the HIF-6 to that. What I can tell you is that there was a significant difference in performance. The HIF-6 running a BEL is a really old dog that looks nice when sitting around but don't expect it to go very far or fast, with a BAL it was able to go but not very fast so I am quickly drawing an educated guess here that perhaps the even richer needle setup of the BCE might be the direction to go in. At this point I have decided to stick with the dual HS4 setup. It's fun and it's summer and time to just get out and drive.

I replaced the "BAL" needle with the "BEL" one. At idle I couldn't get the motor to run without choke or I had to have the idle screw turned down (faster rpm"rpm's) so it won't stall. The CO2 analyzer showed a CO of <.6%. NOT GOOD. I screwed the mixture screw as far as I could and managed to get the CO2 up go 1.5%. Way, way to lean. Switching back to the "BAL" I was running around 1.6% at base line and adjusted the mixture screw to between 2 and 2.5%. Idles better, etc.

HS4 SU Dual Carb Setup

The dual HS4 Su carb setup was the stock setup in Britian. It offered benefits as well as some complexities. The HS Su was an older style and was under pressure to meet the new requirements for environmentally more sound units. Unlike the HIF series it lacked an integrated fuel bowl, had a primitive choking mechanism and more. It did present an impressive look to the engine bay in my opinion and overall response from the combination of them mated to the 1500 is very satisfactory!

I found the SU HS4 Dual Setup definitly Sweet! The reason I had switched over to the dual setup is I had finally gotten tired of trying to figure out the HIF-6 setup and since the dual setup was the original for the British Midget I went for it. The site I purchased my dual setup was: Quantumechanics. The company was good and prompt. They do group purchases of items from England so the price wsa reasonable and the quality of the product not bad. I got the carbs in late Winter/Eary Spring of 2005. The unit itself was in pretty good shape but I rebuilt them to be sure they worked well for years to come as well as polished them so they looked good in the engine bay. Click here to learn more about polishing. Rebuilding the SU carbs are not difficult. Get the "Haynes Teckbook Weber Carburetor Manual by A K Legg, Don Peers, Robert Maddox & John Hayes" and you will do fine.

If you go to add the dual setup to your midget there will be some minor structure modifications. Unlike the British midget the USA midget had an extra cross member added to the engine bay that makes it necessary to cut a small triangle shaped section involving it and the passenger foot well. Otherwise you will have the SU's back carb striking the frame of the car. Having said this there seems to be some information out there that indicates there are two versions of manifolds. One longer then the other. Supposedly if you get the shorter one you don't have to cut the passanger footwell/added triangle of metal. Looking at Moss Europe and asking some individuals in England indicate there is only one manifold type.

Fitting the Dual HS4 Carbs: I found it necessary to make two modifications to fit the carb/manifold unit into the engine bay.

1. The first modification I had to make was fitting the intake manifold onto the engine. It was slightly off so I ground a small amount off from the manifold to fit the bolt pattern on the engine. I had to do the same thing with the headers I added in 2004. Not a big deal just used a 6" bench grinder and took a little bit off and would try it, if it didn't fit I removed more. etc.
2. The more stressful part was having to cut out a triangle shaped metal section at the very top inner corner of the passanger footwell/cross member. This is necessary on the USA Midget but not the English right hand driver midget. The cross member was added to the USA model to reinforce the structure. The rear fuel bowl was the major issue rather then air filter. A cut into both the passanger footwell and cross member was necessary from my observation. I cut almost a diamond shape. Then I was able to flip the part the made up the passanger footwell upside down and epoxied it in. I fabricated a metal cap for the rest.

I have attempted to place the british air filter housing on but found that due to the additional cross member clearance was a problem for the rear of the filter. Currently I am running the standard air filters used by the British version without the metal housing and this looks ok. The other alternative is to go with KN filters as shown at the bottom of this page.

Once this was done the carbs went into place without hitting the passanger well. Next it was time to fit the air filters. I have been struggling with whether I wanted to place K&N air filters or stock with the original air filter assembly. Using K&N with a header I am told can provide up to 10 additional horsepower. Not bad when the original power is rated at only 51 on the American version. To learn more about this read the section "Air Filters" at the bottom of this page.

The following table gives you a rough guide to the needle type you may require, but needle choices will depend upon the range of engine modifications. All needles listed are of the biased pattern, since this was the only type fitted on the 1500 midget.

Needle Suggestion	ID No.	Part No.
Standard Early	ABT	CUD1041
Standard Late	ADT	NZX4013
With K&N Filter & Sports Exhaust	AAQ	CUD1014
With K&N & Sports Exhaust Lean	AAT	CUD1017
As Above + Modified Head	AAM	CUD1011
As Above + Modified Head Lean	AAB	CUD1001
AS Above + Camshaft
With Road 83 Camshaft	AAB	CUD1001
With Fast Road 83 Camshaft	AAL	CUD1010

Return to Top of Page

Fuel Injection

PDF article on converting 1500 to a Mega Squirt Fuel injection system

Bob's website on converting 1500 to fuel injection

Needle Selection for the SU Carbs

SU Carb Needle Selection: Part of the solution to a well performing engine is getting the proper SU needle installed or if unable to find one carefully making one. It's best to assemble some of the following items to assist you in making the correct selection. There are several software packages that makes comparison of needles very nice, a CO2 exhaust analyzer will be very helpful for fine tuning and the books listed will allow you to assemble a good knowledge of what it will take to make this successful. I will add more as I find them.

1. How To Build & Power Tune SU Carburetors by Des Hammill
2. Haynes Teckbook Weber Carburetor Manual by A K Legg, Don Peers, Robert Maddox & John Hayes
3. Web Based Comparison SU Needle Guide - FREE
4. WINSU Software - cost
5. Harbor Freight: Co2 Exhaust Analyzer #91978-0CZA for $160.00

In examining the SU needle I had gotten with the carb I found it labeled as "BAL". The needles have letters/numbers stamped along the base of the needle assembly. The "BAL" needle was cross reference to being used in a dual HIF-6 setup for a Volvo. This needle actually seemed to provide fairly good response except I found I had a significant problem with spark plugs foul during idle and the motor died above 65mph. The reason for the plugs fouling became apparent when I looked at a graph comparison of several different needles, including the "BAL". Almost all needles have the same diameter at points #1 and #2 on the needle. The reason for this is simple. It allows most engines to start without major fine tuning occurring first. Once ignition is obtained fine tuning could then occur.

NOTE: Rarely can an engine be started if the needle is flush with the main jet. It is almost always necessary to lower. See tuning section]. On the "BAL" the thinner diameter allows it to run richer then the typical diameters and therefore caused fouling of the plugs during idle:

How Does the Needle Work? You can think of the needle as a tampered piece of soft metal running thickest at the top points and tapering to ever thinner diameters to the very end of the needle. The needle is held in place in a piston that moves up and down into an orificus called a jet. The jet is in a semi fixed position while the needle moves up and down as the piston is raised or lowered based upon the amount of vacuum created by the engine. As the engine revs higher it produces greater suction and in turn raises the piston still higher thus pulling out the needle. As the needle is pulled out, the needle becomes thinner and more fuel can be drawn up between the needle and jet into the carb. This is a basic explanation but greater details can be found else where if desired.

Needles Information: There are two SU carb needle types. Fixed and spring loaded. Fixed are for earlier models = H and HD. The spring loaded are found on the newer model SU carbs= HS and HIF. The fitted needle position for all SUs is basically the same: the shoulder of the needle should be flush the bottom edge edge of the piston surface. working range of SU needles in each type of SU Carb is as follows:

1. 1 1/4in SU up to 9th measuring point
2. 1 1/2in SU up to 11th measuring point
3. 1 3/4in SU up to 12tho measuring point
4. 1 7/8in SU up to 14th measuring point
5. 2in SU up to 15th measuring point

SU Piston Springs: A piston spring combined with the weight of the aluminum piston provides the necessary downward force to maintain essentially a constant pressure loss(depression) at the throat of the carburetor. The springs are initially color coded with paint for identification. The paint disappears with time. Common piston springs are as follows.

Carb Tuning Sequence: The top of the main jet is the effective point from which the fuel is metered, not the bridge of the carburettor. A good resource on how to tune your engine

Distributor Information: Careful review and assurance that your distributor is in peak condition is another important part of the process that can make or break this experience. Spend a little time making sure you've tuned the distributor, etc. This is a nice article which should assist you in understanding how distributors function. Tuning the Lucas Distributor

More in depth coverage can be obtained from going to Ignition System on the 1500

Use the below selections to jump to specifici area's of interest in setting up your Dual SU Setup

It is recommended that you start the process by using the factory settings. Doing so allows getting the car running, from which you can then fine tune the engine with small adjustments until you have it running perfectly. You need a Hayes manual or other manual that will lead you step by step through the process

To begin the process - Start with the Value Adjustment: Adjusting the valves is the first step in the process to assure a "Great Tuning Job". Without doing this step you will never get the car to run well no matter what else is done. The valves control the flow of gases and plays a major role in the overall engine performance. I learned this lesson after spending hours trying to get the engine to perform "better" without doing the value adjustment first. When I finally did adjust the values and redo everything the engine ran smoother and gave more performance. So don't skip this step.

When going to make the actual value adjustments remember the process is done when the engine is cold. Clearance for the 1500 is noted to be 0.010 according to the Hayes manual. If you use a Clik-Adjust, you'll want to record the number of clicks. Values are numbered 1 to 8 from the front of the engine. The correct order in which to set the valves according to the Hayes Manual is as follows:

The Detailed Steps in Adjustment to the Values Are:

1. Disconnect the battery
2. Remove the spark plugs if necessary. Removing them makes it easy to turn the engine over.
3. Remove valve cover.
4. Using the manual or data copied from the manual turn the motor over by hand until you bring that value into correct position.
5. For example with value 8 open, Value 1 is ready to be adjusted
6. Loosen the locknut on the CLOSED valve, slip the feeler gauge in between the valve stem and the rocker. Turn in the screw until you just feel drag on the feeler gauge.
7. Hold it there while you tighten the nut. Once done you will be able to use the feeler gauge to examine whether or not the clearance is too loose or tight.
8. Repeat (3) and (4) for the other 7 valves
9. Check your work after you tighten the locknut.  Use a feeler and you don't have to crank down on the locknut with all your might.
10. Replace the Valve Cover (with a new gasket if needed).

Again it can not be stress enough about the importance of this step. Without doing this step I spent countless hours trying to time, adjust carbs, etc to get the car to run. It ran but crappy. I had to have the rpm's about 1500 or it idled poorly. Gas mileage sucked, etc. Once the values were tuned I was able to bring the timing into correct alignment, adjust the engine to idle at 800 rpm's and its pretty smooth at this point. Also on the 1500 you want the values mildly loose, meaning having a larger gap then being too tight. So a little value noise isn't a bad thing. If too tight you risk burning your values and worse.

Before putting back the spark plugs, take a look at them. Clean them up and re-gap them at this point. The electrodes should be nice and square, the gap should be right, and the deposits should be a light tan and dry. If you see

• White (or no) deposits mean you're too lean.
• Dark and dry means you're running rich,
• dark and wet (smelling of gasoline)means you're REALLY rich
• Black and oily and you're burning oil.
• Put the plugs back in, or replace them with new ones if it seems reasonable to do so.

This video is very helpful in learning basics about value adjustments with good recommendations on how to do

Vacuum Leaks
Now that you have the valves and spark plugs in good order it's time to start up the engine and allow it to get to operating temperature. A good area to now look into is to check to make sure you don't have a vacuum leak. To do this have the car running and spray carb cleaner where the manifold meets the head plus along the throttle shafts at the carbs, and all vacuum fittings. If the car seems to run differently when the spray hits, there is most likely a vacuum leak that will require you to fix before continuing any further.

I've read that one can also use a vacuum gauge to tell a lot about the engines condition and while I haven't used a vacuum gauge before it sounds like a good investment. Use this link to find out more. Using Vacume Gauge

Adjust Your Points and Coil

If you're certain that your ignition system is functioning well and the timing is good you can skip this but if unsure your next step should be to adjust the points and coils unless you are using an electronic distributor. How? Here is how:

1. Remove the distributor cap and rotor.
2. Take a close look at the points with a strong light. The contact surfaces of the points should be parallel and flat. Worn points will have a slight pit in one, and a slight "peak" in the other. If it's slight, use an ignition file to square the point with the "peak" and make sure the points meet squarely when closed. If the points are badly pitted or burned, replace them and the condenser.
3. Turn the engine so that the points are fully open. Check the point gap with your feeler gauge. If it's off, check your manual for how to adjust it. This is a pain in the posterior, and many people put in electronic ignitions for this reason. This is probably a good time to put a few drops of oil on the felt pad in the end of the distributor shaft (if there is one), and some light grease to the points rubbing block.
4. If you have a Dwell Meter, this will allow you to set the points with more precision. Look at the instructions that come with the meter.
5. Take a close look at the rotor. The contact should be reasonably clean and smooth. If not, clean it up or replace it.
6. Same with the distributor cap. Check the contacts on the inside and if in any doubt replace the cap.
7. If you're replacing the cap, I usually replace the wires as well. If one's gone bad, the other is soon to follow.

Set the Timing. There are two types of timing.

• STATIC TIMING Turn the engine (in the normal direction of rotation ONLY) until the timing marks lineup. (Turning it the other way will introduce error into the timing from slop in the timing gears). Disconnect the contact wire from the coil(the contact wire is the one that goes to the points, + on a Positive Ground car, - on Negative Ground car). Clip your 12v test lamp between the wire you just disconnected and the opposite terminal on the battery (connect to + if it's a Negative Ground car- if it's a Positive Ground car). Loosen the clamp that holds the distributor steady. Is the light on? Turn the distributor body clockwise until it just turns off. If the light is off, turn the distributor body anti-clockwise until it just comes on, then clockwise until it just turns off. If you don't have a test lamp, you can eyeball it. You want it at the point where the block on the points is just being touched by the cam. Tighten the clamp, but take it easy. It only needs to be firm enough to keep the distributor body from moving. Put the rotor and cap back on.
• RUNNING TIMING Find the mark on the timing cover where the timing is supposed to show up (your manual should have a diagram) or use the image below. Put a dab of white-out, caulk or a grease pencil on the spot. Turn the engine over until you see the TDC mark on the crankshaft pulley (your manual should have a diagram). Put a dab of white-out on the spot. Start it up. No start? Check to make sure that you put the points together properly and have the plug wires in the right places (see notes below). If you're supposed to disconnect the distributor vacuum, do it, and plug the line (golf tees work well). Clip your timing light to the #1 plug lead, and shine the light on the timing marks. Do the dots of white-out line up? Pretty close is good enough, and it may jump around a little.) Great. If they don't, loosen the distributor clamp and rotate the distributor until they do. The car may start running pretty badly, but don't sweat it. Tighten the clamp, but take it easy. It only needs to be firm enough to keep the distributor body from moving. Don't forget to reconnect the vacuum line, if you disconnected it.
  
  
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Setting Proper Carburetion:

Having addressed the value adjustment issue and timing issue, it's time to begin calibrating the carbs. Your goal is to initially set each carbs independently and then to finally synchronize them during the last phase. So lets begin.

Hopefully each carb's float level has been setup correctly. If there is excessive fuel consumption, the level may be off and you should consider checking it out. If in doubt it is worth further investigation and I would direct you towards either the Hayes manual or some other manual for detailed instructions on how to set the float level. The manual will give you a measurement between some part of the mechanism that closes the needle and some reference point (like the mounting flange). In all reality, as long as you're within reason, it's more important that they be the SAME, than that they be precisely at 1/8th or 3/16th.

Assuming that we have the float levels set correctly we now must make sure each carb has the same needle and that the needles are setup at the same point. This helps assures that the amount of fuel that is dispensed from each carb will be equal to the other.

To set the needles, begin by turning the jet adjusting nut on each carb counterclockwise (looking at it from above) until it stops [full lean], then turn clockwise [richer] 2 full turns (12 flats). This will set it so that there is enough fuel to start the car.

Take them one at a time, and you'll do fine.

Synchronize the Carbs:

1. Loosen the throttle linkage between the carbs. You need them acting independently. Refer to the image above.
2. Now back the fast idle screws out until they are well clear of the fast idle cam. next back the idle speed screws on each carb (check your manual to find them) out until they just touch the tab they press on, then in about 1-1/2 turns each. This should put the throttle butterflies in pretty much the same position.
3. 
4. Now start the engine up. It will be idling fast.
5. Using a carb synchronizer, you will now begin to adjust both carbs independently by following the instructions that come with the synchronizer.
6. Back the idle speed down by turning the idle screw on each carb back out about 1/4 a turn at a time on each, until you're at around 1000 RPM. (You must back them out the same amount, or you will loose the synchronization).
7. After each adjustment use the synchronizer to make sure each carb is pulling in at the same pressure.
8. You're probably running a bit rich. Test it by pressing up on the piston lifting pin. Check each, one at a time. NOTE: You're only looking to lift the piston about 1/16th of an inch.

Now that the two carbs are individually adjusted it's time to reconnect them.

1. A car that's really well adjusted may idle smoothly as low as 500 RPM, but that's not enough to have the Generator/Alternator and Water Pump do their thing, so take it back up to 800-900.
2. Reconnect the throttle linkage between the carbs.
3. Reconnect the vacuum line to the distributor and snug the distributor clamp.
4. If you took the air filters off, put them back.
5. Now turn in the fast idle screws until they're just about to touch the fast idle cam.
6. Top up the oil in the carb dampers (just to about 1/4 below the top of the inner tube), and reinstall the damper caps.
7. Make sure you've got everything else back where it belongs, and put your tools away

Drive the car, note how it runs, acceleration, idle smoothness, and whether it seems to run out of breath at high RPMs. Feel free to make adjustments, just make sure that you: Adjust both carbs the same way and the same amount, Don't advance the timing a ridiculous amount, Change only one thing at a time, and Take notes on the changes and the result.

Air Filters: Some consideration to air filters should be made at this time as well. Increasing the amount of air flowing into the engine will effect the needle selection as well. The air filter housing used in the British dual setup will not fit in the American version. It hits the frame. This leaves you with the option of using the standard air filters without the housing or switching over to an after market brand. Example - K& N air filters for instance.

I have read in a couple of articles that using the larger tapered filters actually caused a decrease in performance when measured on a rolling road. This contradicts what many have written. It has to do with the air turbulence created by the introduction of large amounts of air. These authors suggest using the pancake style verses the tapered cone shape. I really don't know what is best and would think unless you are racing either one would be fine.

Air Filters:

Some consideration to air filters should be made at this time as well. Increasing the amount of air flowing into the engine will effect the needle selection as well. The air filter housing used in the British dual setup will not fit in the american version. It hits the frame. This leaves you with the option of using the standard air filters without the housing or switching over to an aftermarket brand. Example - K& N air fitlers for instance.

The exact model of K&N Filters is K&N # RU-4410 from what I am being told. These filters come with a large band-type clamp that fits over the neck which fits perfectly over the stock air horn of the carb.

To create the setup as outlined by Hap Waldrop of Acme Speed Shop, you need to get the back plate adaptor for the HS stock carbs. These can be found from an MGB using the HS dual setup or ordered new for about $35 each. See image below to get the exact item you will need.

Hap writes: "Well I finished my new air filters, I had to make one small modification to the stock velocity stack, but other than that it was pretty much bolt on. For what it's worth the filter and velocity stake now is totally unobstructed by bolts, etc...I just counter bored the stock holes to accept a socket head allen bolt so it would be a flush mount, also included is a photo of the velocity stack mounted."

"The filters have a rubber flange on the mounting side, so they slide over the velocity stacks which measures roughly 3.475" and the RU-4410 is 3.5" at the rubber flange, it snugs right over it like it belonged there, and then the suppiled clamps keep them secured, about a easy as you would want it to get".

I have read in a couple of articles that using the larger tapered filters actually caused a decrease in performance when measured on a rolling road. This contradicts what many have written. It has to do with the air turbulence created by the introduction of large amounts of air. These authors suggest using the pancake style verses the tapered cone shape. I really don't know what is best and would think unless you are racing either one would be fine.

Polishing the Carbs

Suggested process from a member on a forum I belong to whose carbs came out great

1. The dashpots, carbs, linkages and all screws/springs were first cleaned with carb cleaner.
2. Then a lot of time spent with sandpaper by hand. Using 220,440,600,1000 and then finally 1200 grit.
3. Then polished with jewelers rouge #5 from OSH.
4. The dashpots were polished with a medium 4" buffing pad.
5. The carb, linkages and screws/springs were done with a Dremel and many different felt bobs.
6. Then everything was polished and sealed by hand using "Master Formula" products.
7. Master Formula Metal Gloss
8. Master Formula Sealer Gloss

A lot of work. If you enjoy this sort of thing; glued to a stool at your work bench for days, with masking tap wrapped around your finger tips, then this project is for you too!

Do becareful not to overheat the units while polishing. Also it is suggested that you do only one at a time so parts aren't mixed up. A useful artical is from Jaguar of North America. Click Here

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