Go to our vacuum unit ID page to look up your Year,  Vehicle, 
Distributor # and original Lucas unit part number. 

Most common lines.

33”  one compression nut,
1 male screw fitting.
MGB to around 1969
24” one compression nut,
1 rubber elbow.
Spridget up to 1969
 26” one compression nut,
1 rubber elbow
TR2, 3, 4
30” two compression nuts

TR4 with HS6
30” one compression nut,
1 rubber fitting
A.H. 100-4 & 100-M
30” two compression nuts

100-6 to BT7
34” two compression nuts

BT7   to BJ8
34” one compression nut,
1 rubber fitting
34” one rubber elbow, one rubber fitting

Jaguar 1950s 6 cyl
20” two compression nuts

early 1960s
20’ one compression nut,
1 rubber fitting
early/ mid 1960s
20” two rubber fittings

Austin Healey Manifold Drain Tubes One set $18.95 with unit & other purchase $14.95

Member of the

British Vacuum Unit
​Canterbury, NH 03224 

When placing an order, please use the Lucas number and code.


When ordering Hex units;  be sure to specify type of cap, aluminum or brass and whether you
would like it stamped with code and part number or stamped with just the code.

If you do not give us this information, you will receive the Hex unit ordered with an aluminum cap, stamped with

part number and code.

We accept checks, money orders, and Paypal. 

If you find we do not have the advance unit you need, you can sent in your old unit to us to be reverse engineered at no additional cost.

All our products have a 2 year warranty.

30-day any reason return policy if any of our products do not exceed your expectations.

Operation of the distributor vacuum advance unit.

Vacuum units are not interchangeableunless they carry the same identification number, as each unit is made up to suit a particular engine.

Additional control of the spark timing is brought about by the vacuum unit. As the unit is connected to the engine intake manifold, its operation depends on the vacuum  present in the manifold.  The vacuum effect varies with the engine load. The vacuum unit produces additional advance when the engine revs are high, but mainly when the load is light. At full throttle when the engine is pulling hard the vacuum unit becomes wholly or partly inoperative. The general effect of the vacuum unit is to increase the liveliness or performance of the engine and enhance a noticeable improvement in fuel economy.

Proper vacuum advance function depends

on a tight vacuum line. Failure due to cracked, chafed pipes or loose unions, result in vacuum advance unit failure to operate


We'll check your unit free of charge for damage and proper movement. 
​We notify you if your unit is correct to the year, distributor number, within code or defected. 
​Your old unit will be returned with or without a purchase of one of our new OE units. Only return shipping and delivery conformation charge apply, usually within $4.00 

Lucas distributor vacuum unit check. Holding vacuum and movement. 

Many vacuum units checked for code operating specs are found defected. 
​Most vacuum gauges are calibrated in inches of mercury. The Mityvac vacuum pump can be use to check fairly accurate movement. 

1- Check for the correct unit. Units are not interchangeable. We list distributor numbers to O.E. units and their codes below or contact us at britishvacuumunit@isp.com

2 - Check the unit holds vacuum. If the unit leaks, it needs replacing. 

3 - Check for proper movement. Most over looked, effecting performance, mileage and cooling. 

The vacuum units operates within the range indicated by the 3 digit code next to the part number. Example; the code 5 12 8 indicates, the unit starts to advance at 5 mercury "vacuum", will reach full advance at 12 mercury "vacuum", with 8 degrees total distributor ignition advance / 16 degrees spark advance at the crank. Units that no longer hold vacuum are obviously bad. It seems most people are under the impression that if the unit holds vacuum, it's considered in good operating condition. This assumption is wrong! Whats not obvious is a majority of original units are dry, stiff or plugged with condensed fuel vapor restricting proper movement and many operate well above the coded range. This renders the unit inoperable with very little benefit, if any at all. Replacing an original unit with a fresh new unit, often has a significant improvement in overall performance, mileage, cooling and often for much less that expensive engine modifications.
Installing a new vacuum unit, make sure the point plate is firm and moves freely. 
Information on our Lucas point plate page.

Often a new unit is installed without careful examination of the point plate and often finding the plate unstable and/or lacking free movement, hindering proper vacuum unit movement. The point plate needs to rotate freely but remain stable from rocking. It's often found to be stiff. There are 2 parts to the plate. The lower plate is secured with screws to the distributor body wile the upper plate clips to the lower plate and needs to be firmly supported, at the same time rotate freely. On one side of the upper plate a spring clip supports the plate in a horizontal position and the other side supports rotation with a guide pin in the lower plate grove. Often the pin and grove are found worn and need repair. The center bearing where the two plates rotate often need attention. If worn it needs to be repaired or replaced. Once the plate assemble is in proper operating condition it can be installed along with the new vacuum unit. Make sure the unit connector link fits freely and firmly in or on the plate connector pin or hole.

Non-vacuum advance performance distributors! 

Should only be installed when involved in high performance racing or under constant wide open conditions. Not good for street use. Anyone replacing a OE vacuum advance distributor with a performance mechanical advance distributor doesn't understand the operation of the vacuum advance unit. The original OE distributor with a vacuum advance unit, enhances cooling, engine efficiency, throttle response,and fuel economy. 

Its also wise to check the vacuum line!

A tight vacuum line and all connections are critical to the vacuum unit operation.Leaky elbows, threaded fittings, pinched, plugged or chaffed lines, are often found and need replacing.

Soft Copper" Vacuum Line Sets

1 compression nut & 1 male compression fitting $18.95 / with unit purchase $14.95
​2 compression nuts $17.95 / with unit purchase $12.95
​1 compression nut & 1 straight or elbow rubber connector fitting $14.95 / with unit purchase $10.95
Line supplied with 2 rubber connector fittings $12.95 / with unit purchase $9.95 
Our vacuum lines are similar to original
​Due to changes that may have been made over the years to carburetors and distributors, state the type of fittings needed when ordering.
Go to our "vacuum unit ID page" to look up your
Year, vehicle, distributor # and original Lucas unit part number.

​Order or questions;Emailbritishvacuumunit@isp.com
We Restore early units to new!  $49.95
Restored to original! Fuel resistant diaphragm, Parts are re-plated, replaced as needed to new original specs. 
Our restored units are returned in NOS condition and properly coded.  
​4 pc micro-adjuster kit supplied with all shaft type units.

New 20D8 units  $79.95
​Daimler #54411675  6 17 9         54412403  4 17 6      Rolls Royce / Bentley #54415488  8 20 8 

TR6 1971-76 Special distributor vacuum advance units “not retard”

Part # 01816 code 6-18-10,    #01315 code 5-13-10 

 Our unit is engineered to take the place of the original vacuum retard unit and change the TR6 retard distributor into a performance advance ignition of the 1960s. The TR6 distributor body is cast as a retard system with no options until now.

Out special advance unit is a custom OE type Lucas unit easy to install in the place of the factory retard unit. You will experience a significant difference in performance, mileage and operating temperature.

Must be connected to ported vacuum! Email us with questions. We'll be happy to help.

Check our ported vacuum page.

$89.95 100% money back guarantee.

1971-73 Your Zenith carburetor may not have ported vacuum!

Your Zenith carburetor may or may not have the threaded port next to the rear top mounting flange over the throttle shaft for ported vacuum. Some 
​with the threaded hole may or may not have the small vacuum drilled through to the throttle from the factory! Zenith-Stromberg may have
​drilled them or may have not completed the process.  This must be done with precision. 
​We now have the tooling to complete the process on your complete carburetor or just the body. 
​Cost $50.00 / $25.00 with unit purchase. Call or Email for information.

Stock TR6 vacuum Retard units (no shaft) 
​$69.952-4-4R and 3-10-7R
Exact to OE specs.
New Later Link
New late vacuum retard with dbl lip Viton seal !
New OE type early threaded cup chamber  & Hex chamber
​$79.95  or our Deluxe  $89.95(Supplied w/4 pc macro-adjuster mounting kit)
New  DVX 2 stud    $79.95

Detailed early & late castings

We supply the 4 pc micro-adjuster                       when shaft units are ordered as a Deluxe.
Our Cup Chamber Lucas Distributor Vacuum Advance units, as shown above,  are manufactured with early or late Lucas body casting,
 zinc plated chambers, threaded or hose vacuum line fitting and shafts.
​Stamped with the Lucas part number and code.
​Modern fuel, oil and chemical resistant, fiber reinforced vacuum diaphragm.

We’ve made every effort to supply you with original type vacuum units,
stock most original units and/or can build any unit you request.
Shaft mount units supplied with micro-adjuster mounting kit in our deluxe kit.
MGA 1955-62  
​#423438  code 7 14 10
Early Austin Healey
#421189   Brass cap code only 5 12 8
Our Early Lucas Distributor Vacuum Advance Unit Hex Chamber Units, as shown above, are manufactured with the early Lucas body casting, 
tin plated chamber and large hex soldered as original with zinc plated shafts. 
​Your choice of aluminum or brass detailed threaded vacuum cap.
Stamped with Lucas part number and code.
​Please request if you want only the code stamped on the cap.  This was how some of the early units were originally supplied. 
​Modern fuel, oil and chemical resistant, fiber reinforced vacuum diaphragm.

Our Products

Lucas Distributor Vacuum Advance Units 
as original 
​We have in stock new OE type DVX, DM, 20D, 22D, 25D and most all 35D, 36D, 45D,
​47D  4, 6, 8 and 12 cylinder Lucas distributor vacuum units.

Early Hex units were manufactured by Lucas in different versions.  For example the "early version" Austin Healey vacuum unit 421189 with vacuum code  5-12-8 was supplied with only the code stamped on a brass vacuum cap.  Shortly later, Lucas produced all these units with the part number and code stamped on an aluminum vacuum cap.  Describe your unit when ordering to assure you receive the original unit as equipped by the factory when your vehicle was produced.

Original type DM, DV, 22D & 25D  Lucas units
Early external mount, Early or later Lucas castings

1971-72 Bentley and Rolls Royce 35D  54425859

Later 35D Units Restored to new $49.95