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ADJUSTABLE FLANGE DISTRIBUTOR ADJUSTMENT

PROCEDURE TYPE 482, 590, 790 AND 791 DISTRIBUTORS

INSTALLATION INSTRUCTIONS

FORM 1316 (REV. C) 06/03

GENERAL INFORMATION

Adjustable flange distributors allow you to raise or

lower the distributor by moving the flange down or up

the distributor shank so that the distributor drive gear

engages properly with the camshaft gear. Adjustment

is necessary anytime the engine block deck height is

changed, cylinder heads have been machined or

offset, or any intake manifold modifications.

Types 482, 590, 790 and 791 mentioned in this

writing are derived from the particular distributor’s part

number (example: 3448205; 3479005). Type 482’s

shallow groove on the upper shank of the distributor

is the stock flange height reference for 265-454

Chevrolet engines (figure 1). Type 790’s and 791’s have

two shallow grooves. The lower shallow groove on the

upper shank of the distributor is the stock flange

height reference for Chevrolet V8 265-454 engines.

The upper groove on the upper shank of the distri-

butor is the stock flange height reference for Chevrolet

V8 Tall/Truck Block engines (figure 2).

Align the bottom of the flange with the shallow groove

and tighten the flange screw to position the flange at a

stock flange height reference. Tighten the set screws.

Step 1

Disconnect your ignition system. Turn the engine

crankshaft in the direction of rotation until the timing

mark lines up with the top dead center (TDC) mark on

the timing tab and #1 cylinder is on its compression

stroke.

NOTE: Removing the spark plugs may make it

easier to turn the crankshaft.

Step 2

Remove the distributor cap.

Step 3

Loosen the flange and set screws. Slide the flange up

the upper shank.

MALLORY TECHNICAL SUPPORT

(775) 882-6600

www.mrgasket.com

FIGURE 1

FIGURE 2

TYPE 590,

TYPE 790,

AND

TYPE 791