Thread: Timing 101
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Old 01-19-2008, 01:17 AM   #5
70rs/ss
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Re: Timing Stuff You Always Wanted to Know

The following listing (Non-HEI) is as follows: The first two part number listings are the two numbers that are most commonly used in a Chevrolet performance application. The “B1” can is the most versatile and user-friendly unit for a good performance street engine. As you can see, it was selected by GM for use in most high performance engines due to its ideal specs. The “B28” can was used on fuel injected engines and a few select engines that produced very poor vacuum at idle. 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. The Chevrolet applications are listed first by application, followed by a complete listing of all of the units used on any GM product (all GM units are interchangeable, so you can use a Cadillac or GMC Truck unit on your Vette, if that’s what you want to do).

Non-HEI Distributors:

P/N ID# Application Starts @ “Hg Max Adv
(Distr. Degrees @ “Hg.)

VC680 B1 1959 – 63 All Chevrolet 8-11 8 @ 16-18
1964 Corvette exc. FI
1964 Impala, Chevy II
1965 396 High Perf.
1965-67 283, 409
1966-68 327 exc. Powerglide
1967-68 All 396
1969 Corvette 427 High Perf.
1969 396 Exc. High Perf.
1969 Corvette 350 TI
1969-70 302 Camaro
1970 400 4-bbl
1970 396 High Perf.
1970 Corvette 350 High Perf.
1973-74 454 Exc. HEI

VC1810 B28 1965 409 High Perf. 3-5 8 @ 5.75-8
1965 327 High Perf.
1966 327 High Perf.
1964-67 Corvette High Perf. FI

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VC1605 B9 1965 impala 396 Exc. High Perf. 7-9 10.3 @ 16-18
1965 327 All Exc. FI
1969 327 Camaro, Chevelle, Impala
1969-70 Corvette 350 Exc. High Perf.
1969-70 350 4-bbl Premium Fuel
1970 350 Camaro, Chevelle, Impala High Perf.
1971-72 350 2-bbl AT
1971-72 307 All

VC1675 B13 1968 327 Camaro Powerglide 9-11 8 @ 16-18
1968 327 Impala AT
1968 307 AT
1968 302, 307, 327, 350 Camaro, Chevy II
1970 350 Camaro, Chevelle Exc. High Perf.

VC1760 B19 1969 350 Camaro, Chevelle, Impala 4-bbl 5.5-8 12 @ 14-18
1969-70 350 2-bbl

VC1765 B20 1965 396 Impala High Perf 5-7 8 @ 11-13
1966-67 Corvette Exc. High Perf.
1966-67 Impala 427 Exc. High Perf.
1966-68 327 Powerglide Exc. High Perf.
1969 307 All
1969-70 396, 427 Camaro, Chevelle High Perf.
1970 400 2-bbl
1970 307 MT
1973 Camaro 350 High Perf.

VC1801 B21 1971 350 2-bbl 7-9 10 @ 16-18
1971-72 400, 402
1971-72 307 AT

VC1802 B22 1971-72 350 4-bbl 7-9 8 @ 14-16


Other Part Numbers & Specs:

VC700 B3 8-10 11.5 @ 19-21
VC1415 M1 6-8 10 @ 13-15
VC1420 M2 5-7 11 @ 16-17
VC1650 B12 8-10 10 @ 15-17
VC1725 B18 8-10 12 @ 13-16
VC1740 A5 6-8 12 @ 15-17.5
VC1755 A7 8-10 12.5 @ 18-20.5
VC1804 B24 6.5-8.5 10 @ 12-14
VC1805 M13 6-8 12 @ 14.5-15.5
VC1807 B25 5-7 8 @ 13-15
VC1808 B26 5-7 8 @ 11-13
VC1809 B27 5-7 9 @ 10-12
VC1812 B30 5-7 12 @ 11.75-14

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

VC1834 AR9 4-6 13 @ 13-16

VC1835 AS2 1975-76 350 Olds 5.5-7.5 12 @ 15-17

VC1836 AR10 1977 305 All Hi Alt, Exc. Calif. 3-5 9 @ 11-13
1977 350 All exc. Calif.
1977 350 Vette Exc. Calif, Exc. Hi Perf
1976 305 All Exc. Calif
1976 350 All Exc. Vette, Exc. Calif
1976 350 Vette Exc. Calif., Exc. Hi Perf
1975 262, 350 All w/2-bbl carb
1975 350 All 4-bbl w/ 1112880 & 1112888 Distr.
1977 305 Chev Truck Light Duty
1975-76 350 El Camino 2-bbl

VC1837 AR11 1976 305 Blazer, Exc. Calif 6-8 12.5 @ 10.5-13.5
1976 350/400/455 Pontiac 4-bbl

VC1839 AR13 4-6 12 @ 11-13

VC1840 AR14 1975-76 350/400/455 Pontiac Firebird 6-8 10 @ 9-12

VC1841 AS3 1975-76 500 Cadillac Calif. 5-7 10 @ 13-14

VC1842 AS4 1976 350 Olds Cutlass 5-7 12 @ 13-15

VC1844 AR16 3-5 12 @ 13.5-15.5

VC1845 AS5 1978-79 425 Cadillac w/F.I. 4-6 14 @ 14-16
1977 425 Cadillac

VC1846 AR17 1977 301 Buick Skylark 3-6 13 @ 10-13
1977 301 Pontiac

VC1847 AS6 1978 403 Motor Home 4-6 12 @ 12-14
1977-79 350/403 Buick LeSabre Hi Alt, Riviera, Olds
1977-79 350/403 Pontiac Hi Alt

VC1848 AR18 4-6 12 @ 9-12

VC1849 AR19 4-6 12 @ 7-10

VC1850 AR20 1977 350/400 Pontiac 4-6 10 @ 8-11

VC1851 AR21 1977-79 350 Buick LeSabre, Century 5-7 12 @ 11-13
1978-79 350 Pontiac

VC1852 AR22 77-78 305/350/400 Chev Truck, Heavy Duty 7-9 5 @ 12-14
1975-76 350/400 Chev Truck Heavy Duty

VC1854 AR24 3-5 13 @ 10-13

VC1855 AS7 1977-79 260 Olds Cutlass 3-5 15 @ 10-12

VC1856 AR25 3-6 15 @ 10-14

VC1857 AR26 3-6 12 @ 13-16
VC1858 AR27 1978-79 305 All 3-6 9 @ 11-13
1978 350 Camaro
1978 305 Chev Truck, M/T, Light Duty
1978 350 Chev Truck Hi Alt
1978 305/350 Buick & Olds
1978-79 305 Pontiac

VC1859 AR28 1979 350 Vette Exc Hi Perf 3-6 10 @ 9-12
1978-79 305 w/1103282 Distr., Incl. El Camino A/T
1979 350 Camaro, Impala, Nova, Malibu, Monte
1979 350 Suburban
1979 350 Buick Century
1978 305/350 Buick & Olds
1978-79 305 Pontiac Hi Alt.

VC1860 AR29 3-6 12 @ 10-13

VC1861 AR30 1978-79 301Buick 3-5 13 @ 11-13
1979 301 Olds
1978-79 301 Pontiac

VC1863 AR32 2-4 10 @ 11-13

VC1864 AR33 1978 305 Chev Truck, A/T, Light Duty 4.5-6.5 13 @ 11-13

VC1865 AR34 1973-74 350 Vette Special Hi Perf 3-5 15 @ 8.5-11.5

VC1866 AS8 1978-79 425 Cadillac w/carb 3-5 14 @ 13-15

VC1867 AS9 2-4 10 @ 8-10

VC1868 AR35 1979 305 Chev Truck & El Camino 2-4 10 @ 6-9
1979 305 Buick & Olds
1979 305 Pontiac A/T

VC1869 AS10 2-4 12 @ 8-11
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