Jetting Amal Mk1 Concentrics for Vincent Twins, and Singles

(These specifications are for 32mm 932 carbs)


I will show jetting specs here that I have used for 1,000cc Vincent Rapides, and Black Shadows using Mk1 standard cams, and low compression. Then for those with hotter motors, I will include the jetting I use on my 1,164cc Big Bore motor using Mk2 "Lightening" cams, and 10:1 compression. These numbers might not be absolutely correct for all Vincents, but it will offer a very close base line for you to fine-tune by.


Jetting for Standard Rapide, and Shadows (Using original 932's):

Slide=3.0 (gives better throttle response than a 3 1/2)

Needle Jet=106 for Sea Level, and 105 for High Elevation

Needle=(2) Bands, Use the middle clip for both Sea Level, and High Elevation

Main Jet=180 (Hi Elev or cold climate), and 200 (Sea Level)

Pilot Jet=#30

Mixture Screw=Between 1 and 1 1/4 turns out for fastest idle speed

Float Level=.080" below edge of bowl (black float set at bowl edge)

Feed Nozzle=Cut away the entire back half (downstream)

Timing=34 Degrees Full Advance

Spark Plugs=NGK B8EGV Gold Paladium Racing Plugs @ .020" Gap


Jetting for My 1,164cc Big Bore Hi Compression motor (Using original 932's):

Slide=3.0

Needle Jet=(107 Sea Level, and 106 High Elevation)

Needle=(4) Bands, Middle clip for Hi-Elev., and Middle clip for Lo-Elev.

Main Jet=(220 Sea Level, and 200 High Elevation)

Pilot Jet=#35

Mixture Screw=Between 1 and 1 1/2 turns out for fastest idle speed

Float Level=.080" below edge of bowl (Black float set at bowl edge)

Feed Nozzle=Cut away the entire back half (downstream)

Timing=34 Degrees Full Advance

Spark Plugs=NGK B8EGV Gold Paladium Racing Plugs @.020" Gap


Jetting for Standard Rapides, and Shadows (Using New Amal 932 Premier Carbs):

Slide=3.0 (Gives better throttle response than a 3 1/2)

Needle Jet=106 for Sea Level, and 105 for High Elevation

Needle=(2) Bands, use the middle clip for both Sea Level, and High Elevation

Main Jet =180 (High Elevation, or Cold Climate), and 200 (Sea Level)

Pilot Jet=.017" for High Elevation, .019" for above Sea Level, or .021" at Sea Level

(Try the .021" over the .019" to cure slight surgeing just above idle)

Mixture Screw=Between 1 and 1 1/4 turns out for fastest idle speed

(Mixture near 1 1/4 turns for fastest idle confirms the correct pilot jet choice)

Float level=Top of Black Float at top of bowl (Fuel Level=.210" plus or minus .040" from bowl top edge)

Feed Nozzle=Cut away the entire back half (downstream)

Timing=34 Degrees Full Advance

Spark Plugs=NGK B8EGV Gold Paladium Racing Plugs @ .020" Gap


Amal 932 Premier Carb Notes:

With the introduction of the new Premier Series Mk.1 Concentrics, there were some new, and needed improvements. Here they are: 1)Instead of the same pot-metal slides as the main body, which quickly wear out, there are now hard-anodized slides in all the same cut-aways, and dimensions. 2) They now use the new black float, which is a semi-solid foam, with adjustable tangs, which pick-up the Viton tipped brass needle. 3) The main difference is the new pilot jet circuit, which is interchangable within 5 jet sizes. It replaces the low speed restrictor jet found under the air mixture screw. They screw right in, and put the jet outlet at the same spot where the restrictor was. The restrictor came into play in 1968 (the 2nd year for Concentrics). These restrictors were usually too small, and needed to be drilled out with at least a .040" drill, and then installing the appropriate low speed jet. The reason for moving to a restrictor, or the Premier low speed jet closer to the venturi mixing chamber had to do with the mass of the fuel between the screw-in jet, and the venturi. They say the Premier works better? And they cost more! Who needs money, anyway?


The Pilot or Low Speed jets are marked differently than the original style jets. The originals were marked 15,20,25,30,35, etc. This represented how many cc's of fuel could pass per minute. The new Premier low speed jets are marked two ways. First with their actual jet size in decimal (.015" - .023"). They also have a series of thin marking bands around them. Here is how it works: .015"= #15 (1-band),.017"= #20 (2-band), .019"= #25 (3-band), .021"= #30 (4-band), and .023"= #35 (5-band).


I found this info nearly impossible to find. After much research, and 3 full days with a nice Black Shadow on my dyno, with sniffer, I came up with these results. The customer said his Vincent (one of 6) has never run so well! I hope this info helps you in the future.


CONTACT INFORMATION:


James R. Mosher

(505) 466-7870