ROCHESTER M4MC 4-Barrel: Overhaul: Reassembly

NOTE: Use new gaskets and seals. Make sure that new gaskets fit correctly and that all holes and slots are punched through and correctly located.

To reassemble carburetor, reverse disassembly procedure and note the following:

Install fuel inlet needle pull clip over edge of flat on float arm facing float. Do not hook clip in holes in float arm.
Install plastic float bowl filler block after float level adjustment and before metering rod installation.
The intermediate choke shaft lever and fast idle cam are installed correctly when tang on lever is beneath fast idle cam. Make choke coil lever adjustments before installing choke coil cover.
NOTE: If choke coil cover was removed, it will be necessary to install self tapping screws (supplied in service kit) to replace retainer rivets. Before installing cover, start self tapping screws into choke housing, making sure they start easily and are properly aligned. Remove screws and proceed as follows:
Place fast idle screw on high step of fast idle cam. Install choke coil cover, aligning notch in cover with tab on cover retainer (supplied in service kit). Install retainer with tab into screw hole in housing nearest to front of carburetor. Install remaining self tapping screws and tighten.

Fig 1: Air Horn Screw Tightening Sequence
Courtesy of GENERAL MOTORS COMPANY

When installing air horn screws, note that the California models are equipped with 13 air horn-to-float bowl screws and Federal models are equipped with only 9. For California models, install and tighten screws evenly, securely and in order shown in Fig 1 . On Federal models, tightening sequence is 1 thru 7 as shown, then 10 and 11.

CARBURETOR ADJUSTMENT SPECIFICATIONS

Application

Float Level Setting

Accelerator Pump

Choke Coil Lever Setting

Choke Rod Setting

Vacuum Break

Air Valve Spring Setting⁽¹⁾

Auto. Choke Setting

Choke Unloader Setting

Stem Setting

Hole Setting

Front Setting

Rear Setting

17080201

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080205

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080206

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080212

3/8"

9/32"

Inner

.120"

46°

24°

30°

3/4

Index

40°

17080213

3/8"

9/32"

Inner

.120"

37°

23°

30°

Index

40°

17080215

3/8"

9/32"

Inner

.120"

37°

23°

30°

Index

40°

17080224

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080225

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080226

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080227

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080229

3/8"

9/32"

Inner

.120"

37°

23°

30°

Index

40°

17080290

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080291

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080292

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080295

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080297

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080503

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080506

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080508

15/32"

9/32"

Inner

.120"

46°

.....

26°

7/8

Index

42°

17080512

3/8"

9/32"

Inner

.120"

46°

24°

30°

3/4

Index

40°

17080513

3/8"

9/32"

Inner

.120"

37°

23°

30°

Index

40°

17080515

3/8"

9/32"

Inner

.120"

37°

23°

30°

Index

40°

17080523

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080524

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080525

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080526

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080527

15/32"

9/32"

Inner

.120"

46°

.....

23°

7/8

Index

42°

17080528

15/32"

9/32"

Inner

.120"

46° 37°

.....

23°

7/8

Index

42°

17060529

3/8"

9/32"

Inner

.120"

.....

23°

30°

Index

40°

⁽¹⁾	Specification is amount of turns.