Double Diaphragm Distributor

1600 cc models have a distributor with two separate diaphragms, while 2000 cc models use a single diaphragm which is operated in both directions. Control of diaphragm(s) is accomplished by two vacuum take offs, one on carburetor and one on intake manifold. One diaphragm senses manifold vacuum and provides normal vacuum advance. Other diaphragm senses carburetor vacuum and retards ignition timing during idle and deceleration conditions.