Engine and Driveline
Fuel Pump/Carburetor
Two fuel pumps were used on SS optioned 1970 Chevelles; the “727”
and “768” fuel pump. The “727” pump does not have a return line where
the “768” fuel pump does. Note the battery cable covering and frame-mounted
clip to keep it out of harm’s way.
Two fuel pumps were used in 1970, the 40727 fuel pump with no vapor return line and the 40768 fuel pump with the vapor return line. All L78 engines and “early” LS6 engines use the 40727 fuel pump. All L34 and LS5 engines use the 40768 fuel pump. The LS6 engine initially used the 40727 fuel pump but changed to the 49768 fuel pump. The change is dependent on the final assembly plant. Research shows the Atlanta plant changed between 03-25 and 03-31, the Baltimore plant changed on 02-13, the Kansas City plant changed between 02-13 and 02-16, and the Van Nuys plant changed between 04-06 and 04-21. The correct fuel pump for your application is noted on the build sheet in box #33 with either 727 or 768. If you do not have your build sheet, simply check to see if there is one line or two in the fuel pump.
All 1970 L78 and LS6 engines were equipped an aluminum intake manifold
and Holley 4-barrel carburetor. The intake was supplied by the Winters
foundry and can be identified by the “snowflake” cast into the manifold.
Four different Holley carburetors were used dependent on the transmission
type and whether E.E.C.-equipped or not. The 1970 model year would be
the last year for both the aluminum intake and Holley carburetor.
All RPO L78 and 1970 LS6 engines came with a Holley 4-barrel carburetor and aluminum intake manifold. Unlike earlier L78 intake manifolds the 1970 L78/LS6 intake manifold was “low-profile” and was originally designed for the Corvette for hood clearance but GM decided to use the same intake for other applicable Chevrolet engines. The 1970 model year would be the last year an aluminum intake manifold or Holley carburetor would be used. All L34 and LS5 engines continued to use the cast iron intake manifold and Rochester Quadra-Jet carburetor. The cast iron intake manifolds were the Corvette's “low- profile” just like their aluminum counterparts.
1970 LS5 engine with low profile cast iron intake manifold and
Rochester carburetor.
Holley Carburetors for Chevelles (Group 3.275)
| Year(s) | Engines | GM Part # | Holley List # |
| 65 | w/Sp. H/Per (327) | 3863150-DG(2) | 3043A |
| 65 | 396 | 3878261-EH | R-3310A |
| 66 | 396 (exc. P.G., A.I.R., H/Per.) | 3874898-ER | 4-3139A |
| 66 | w/P.G. (396) (exc. A.I.R., H/Per.) | 3868864-ES | R-3140A |
| 66 | w/P.G. (327) (exc. A.I.R., Sp. H/Per.) | 3875964-DB | R-3230A |
| 66 | w/H/Per. (396) (exc. A.I.R., P.G.) | 3886087-EJ | R-3419A |
| 66 | P.G. w/H/Per. (396) (exc. A.I.R.) | 3886088-EX | R-3420A |
| 66 | (A.I.R. w/P.G.) w/H/Per. (396) | 3892338-EZ | R-3608A |
| 66 | (A.I.R. w/H/Per.) (396) (exc. P.G.) | 3892339-EY | R-3609A |
| 66 | w/Sp. H/Per. 396 | 3893229 | R-3613A |
| 67 | w/Sp. H/Per. (exc. A.I.R.) (327) | 3903389-DC | R-3806A |
| 67 | w/Sp. H/Per., A.I.R. (327) | 3903391-DV | R-3807-1A |
| 67 | w/H/Per., A.T. (exc. A.I.R.) (396) | 3908956-EX | R-3836A |
| 67 | w/H/Per. (exc. A.T., A.I.R.) (396) | 3908957-EJ | R-3837A |
| 67 | w/H/Per., A.I.R., A.T. (396) | 3908958-EZ | R-3838A |
| 67 | A.I.R., w/H/Per. (exc. A.T.) (396) | 3908959-EY | R-3839A |
| 67 | w/Sp. H/Per. (exc. A.I.R.) (396) | 3916143-CT | R-3901A(1) |
| 67 | A.I.R. w/Sp H/Per. (396) | 3916145 | R-3911A |
| 68 | w/Sp. H/Per. (exc. A.T) (396) | 3923289-DZ | List 4053 |
| 69 | w/Sp. H/Per. (396) | 3959164-GE | List 4346 |
| 70 | w/Sp. H/Per. (exc. A.T., E.E.C.) (396,454) | 3967477-GG | List 4557 |
| 70 | w/Sp. H/Per., E.E.C., (exc. A.T.) (396,454) | 3967479-GM | List 4491 |
| 70 | w/Sp. H/Per., A.T., E.E.C. (396/454) | 3969894-GP | List 4556 |
| 70 | w/Sp. H/Per., A.T. (exc. E.E.C) (396/454) | 3969898-GR | List 4492 |
| 71 | w/Sp. H/Per., (exc. A.T.) (454) | 3986195 | List 4803 |
| 71 | w/Sp. H/Per., A.T. (454) | 3986196 | List 4802 |
(1) The GM part number 3916143 appears in both the AIM
and the Chevrolet Parts & Accessories Catalog. The Holley List
Number R-3901A appears in the Chevrolet Parts & Accessories Catalog.
It is suspected that the Holley List Number is 3901 in the catalog
is a misprint and should be 3910.
(2) Some may not be stamped with the suffix DG.
Example of an L78/LS6 Holley carburetor; GM part number and broadcast
code are stamped on the air horn (3967477-GG) and Holley's list
number (4557). The date, 992, is 1969 (9), September (9), 2nd
week (2)..
Rochester Carburetors for Chevelles (Group 3.275)
Specific Rochester carburetor applications for each year are listed under each year's section.
1975 and EarlierExample stamped on carburetor:
7028219
DG 1658
70 ~ Prefix code for all late 1960's & 1970-1975
Rochester carburetors
2 ~ Decade
2 ~ 1960's
3 ~ 1960's with A.I.R
4 ~ 1970 to 1975
8 ~ Year
2 ~ Model
0 ~ Monojet (1-bbl) Federal Standards
1 ~ Two jet (2-bbl) Federal Standards
2 ~ Quadrajet (4-bbl) Federal Standards
3 ~ Monojet (1-bbl) California Standards
4 ~ Two jet (2-bbl) California Standards
5 ~ Quadrajet (4-bbl) California Standards
6 ~ Varijet (2-bbl) Federal Standards
1 ~ Division
0, 1, 2 ~ Chevrolet
4 ~ Buick
5 ~ Oldsmobile
6, 7 ~ Pontiac
9 ~ Transmission
Odd numbers w/manual transmission
Even numbers w/automatic transmission
DG ~ Broadcast (Customer) Code
1658
165 ~ 165th day of the year beginning with January 1
8 ~ year
Early Carter & Rochester Quadra Jet carburetors will have a circular metal tag affixed to the front, left side. Date code is a letter/number combination where the letter is the month, January through December (A...M omitting the letter "I") and the number is the day of the month.
Broadcast (or Customer) Code is shown on build sheet, block 18,
and are not necessarily plant specific. For example the code "FF"
has been seen on both Atlanta, Kansas City, and Van Nuys build
sheets; Baltimore will show FF-BH.
704 = 1970-1975
2 = Quadrajet (4bbl) Federal Standards
0 = Division (Chevrolet)
4 = Automatic transmission
FF = Customer code
078 = March 19 (Julian date)
0 = 1970 model year
