Chevrolet 1977 light duty truck User Manual download pdf (Page 5)

The following listing (HEI) is as follows: The first four part number listings are the 4 numbers that are most

commonly used in a Chevrolet performance application. The "AR12" can is the most versatile and user-friendly

unit for a good performance street engine. The AR 15 and AR23 are almost identical, with only slight variations in

their "start-stop" specs. The "AR31" can is the HEI equivalent to the "B28" Hi-Perf can used on the early engines:

The advance comes in very quick on this unit - too quick for many performance engines. Do not use this very quick

unit unless you have a cam/engine combination that really needs an advance like this. It can be used as a tuning aid

for problem engines that do not respond well to other timing combinations, and can be successfully used in

applications where direct manifold vacuum is applied to the can (see paragraph and discussion on this above)

After this, the listing is by Echlin part number. All GM HEI vacuum advance units are interchangeable, so you can

use a Cadillac or GMC Truck unit on your Vette, if that's what you want to do.

HEI Distributors:

P/N ID# Application Starts @ “Hg Max Adv

(Distr. Degrees @ “Hg.)

VC1838 AR12 1975 350 Buick 7-9 7 @ 10-12

VC1843 AR15 1977 305 All Exc. Hi Alt, Exc, Calif. 3-5 7.5 @ 9-11

1974 400 All w/2-bbl

1977 305 El Camino

1976 262 Monza Exc. Calif

1976 350 Vette Hi Perf, Incl. Calif

1975 350 Z-28

1977 305 Buick Skylark

VC1853 AR23 1976 350 All Calif. 5-7 7.5 @ 11-12.5

1976 350 Vette Calif., Exc. Hi Perf

1976 400 All, Exc. Calif

1975 350 4-bbl

1974 350 All w/1112528 Distr.

1978 350/400 Heavy Duty Truck, Exc. Calif, Exc. Hi Alt.

VC1862 AR31 2-4 8 @ 6-8

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VC1703 N/A 1978-79 Vette Special Hi Perf N/A N/A

1979 305 El Camino Calif.

1978-79 350 Blazer & Suburban

1979 Buick 305/350

VC1825 AR1 1976 454 Caprice, Impala 3-5 9 @ 6-8

1975 454 Caprice, Chevelle, Monte, Suburban

VC1826 AR2 5-7 12 @ 10-13

VC1827 AR3 5-7 9 @ 9-11

VC1828 AR4 1975-76 350 Buick & Olds 6-9 10 @ 12-14

1976 350 Pontiac

VC1831 AR7 6-8 12 @ 14-16

VC1832 AR8 1975-76 455 Buick Electra 4-6 12 @ 12-14

VC1833 AS1 1975-76 500 Cadillac Exc. Calif. 4-6 14 @ 15-16

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Chevrolet 1977 light duty truck User Manual Page 5