Mallory Distributor, Unilite with Vacuum Advance, 4754101 is an Optical Pickup Distributor with a velvety smooth centrifugal advance. This distributor also has vacuum advance, for better MPG, throttle response, and much cooler running! This is the finest distributor you can get for aircooled VW's!
This distributor requires a coil resistance of 1.5 Ohms or greater, OR it can be used to trigger a CDI Box (like a Mallory Hyfire). If you are not sure of your coil's resistance, measure it to prevent Unilite Module Damage!
Fully adjustable centrifugal advance (if you get the optional spring kit), and you can adjust how much advance you have, AND how fast (and when) it comes it by loosening the centrifugal stops held in place with an Allen setscrew. Centrifugal timing is adjustable between 16-32 crank degrees. The spring kit gives you 14 different advance curves, for a LOT of tunability.
Each of these can be further tuned by slightly bending the centrifugal spring mounting tab (this loosens or tightens the spring a little, and advances or retards the advance curve by up to 300 RPM from the spring's setting). We prefer to set it at about 8 degrees initial (too much means tough starting when the engine is hot), and have the centrifugal advance limited so it totals 28 degrees (36 for Semi-hemi engines), set up so the advance comes in sooner than the 009. The faster initial advance WILL give a crisper throttle (many race cars run LOCKED 30-32 degrees, for example) and more power from idle-3000, with less/no hesitation.
It gets better! In addition to drivability improvements, vacuum advance will help you dual weber/dellorto guys can get another 4-5 mpg, AND the engine will pull harder off idle than ever before, and use less gas doing it (you can lessen the accellerator pump squirt, and idle jet size), while also running cooler! :-)
The vacuum advance is FULLY ADJUSTABLE with a 3/32" allen key in the vacuum port to adjust the vacuum diaphragm, and you set it according to vacuum measurements you get from your carb(s). This means it doesn't matter what carb(s) you have, and it also doesn't matter what cam you are running! While other guys are running 30 degrees of full advance, you will be cruising around at 42 degrees on the highway, which optimizes mileage! It's important to know that the 30 degree setting is fine for full throttle, but at part throttle (cruise) you can use 42 degrees. If you are only running 32, your timing is retarded 10 degrees from optimal! Retarded timing creates MORE HEAT. This means you run cooler and use less gas if you have a properly working vacuum advance (VW put it on all their engines for a reason).
All you need is a ported vacuum source ("ported" means the vacuum is coming from right above the throttle plate); do NOT run this to manifold or venturi vacuum!. Ported vacuum is 0 vacuum at idle, and 15-25" of vacuum at 3000 RPM and 1/8 - 1/2 throttle.
The Mallory Cap is larger than stock distributor cap to prevent cross firing, and uses STOCK type plug wires (You have to buy special wires with MSD and Pertronix Distributors).
The Unilites look VERY different than other distributors, they are slightly bigger, measuring 3 1/8" diameter from the distributor clamp to the top of the distributor cap. This also fits the T-4 engines, even with the stock cooling tin, provided you use the stock oil pressure sending unit. IF you use a VDO sending unit (gauge, etc), you need to get a sending unit relocation kit from us.
The Unilite distributors are optically triggered (not magnetic). The Unilite system requires 3 connections, 12V (coil +), ground, and trigger (to coil -). They are designed to drive any coil with an impedance greater than 1.5 ohms, so you can run it stand alone with a coil, OR trigger a CD box (Jacob's, MSD, Mallory, Universal, Tiger, etc).
Basically, the Unilite distributor is like having a fully adjustable distributor, with the inclusion of a Pertronix/Compufire built in! Incredibly reliable, and you can even use it with a stock coil if you want! MSD distributors must be used with an ignition box, which is one primary reason why we carry Mallory and not MSD.