ZZ4 Timing and Spark Plug Gap
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Joined: Apr 2001
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From: Was New Orleans but swam to Baton Rouge LA
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Re: ZZ4 Timing and Spark Plug Gap (kgraumann)
Timing should be set at 10 degrees initial. It comes from the factory set at zero. Spark plug gap depends on the plugs. The MR or marine plugs in some ZZ4's get gapped to .45 along with the rapid fires. The other plugs are set at .35.
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Joined: May 2001
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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St. Jude Donor '06-'10, '13
Re: ZZ4 Timing and Spark Plug Gap (kgraumann)
According to the GM H.O. 350 Engine Assembly manual:
"Set initial spark timing at 10 degrees before top dead center at 650 RPM with the vacuum advance line to the distributor disconnected and plugged. This setting will produce 32 degrees of total advance at wide open throttle.
The HEI vacuum advance canister should be connected to ported vacuum source (no vacuum at idle).
Advance curves: The HEI distributor supplied with the (ZZ4) has mechanical centrifugal and vacuum advance with the following curves:
Mechanical:
RPM ----- Advance
1100 -------0.0
1600 -------12.0
2400 -------16.0
4600 -------22.0
Vacuum:
vacuum (in Hg) Advance
3.00 -------------0.00
7.50-------------20.00."
"Spark plugs: The ZZ4 is supplied with AC MR43LTS spark plugs. When servicing use AC FR5LS, 904, or MR43LTS spark plugs. Set the plug gap at .035 - .040. If a colder plug is required for moderate competition or sustained high speed operation, FR3LS or FR2LS plugs are recommended."
Whew ---- I need to go rest my wrists now.........
"Set initial spark timing at 10 degrees before top dead center at 650 RPM with the vacuum advance line to the distributor disconnected and plugged. This setting will produce 32 degrees of total advance at wide open throttle.
The HEI vacuum advance canister should be connected to ported vacuum source (no vacuum at idle).
Advance curves: The HEI distributor supplied with the (ZZ4) has mechanical centrifugal and vacuum advance with the following curves:
Mechanical:
RPM ----- Advance
1100 -------0.0
1600 -------12.0
2400 -------16.0
4600 -------22.0
Vacuum:
vacuum (in Hg) Advance
3.00 -------------0.00
7.50-------------20.00."
"Spark plugs: The ZZ4 is supplied with AC MR43LTS spark plugs. When servicing use AC FR5LS, 904, or MR43LTS spark plugs. Set the plug gap at .035 - .040. If a colder plug is required for moderate competition or sustained high speed operation, FR3LS or FR2LS plugs are recommended."
Whew ---- I need to go rest my wrists now.........
