1970 LS5 454 ignition?
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Navigator
Joined: Apr 2011
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1970 LS5 454 ignition?
Hi, I bought a 1970 Corvette convertible with a LS5 454, manual gearbox. The owners manual calls for 2 degrees ignition advance at idle with vacuum connected, but this seems a very low figure to me, can anyone confirm this is correct? When I bought the car it had like 20 degrees! The engine idles much better with this kind of advance. The centrifugal advance works fine.
thanks, Tom
thanks, Tom
Melting Slicks
Joined: May 2009
Posts: 3,079
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2024 C3 of the Year Finalist - Unmodified
That 2 degree figure was factory BS in order to minimize warranty claims. It will seriously kill your performance. I think the tune-up sticker on my firewall says 4 degrees BTDC.
Get either a degree tape for your balancer or use an advance timing light. Set your total advance for 36 degrees (with vacuum plugged) and don't be concerned where your initial lands...probably will end up around 14 to 16 degrees BTDC. Then hold on to the steering wheel when you stomp on that bad boy. Think seriously about changing the vacuum advance source from ported vacuum to full manifold vacuum.
Get either a degree tape for your balancer or use an advance timing light. Set your total advance for 36 degrees (with vacuum plugged) and don't be concerned where your initial lands...probably will end up around 14 to 16 degrees BTDC. Then hold on to the steering wheel when you stomp on that bad boy. Think seriously about changing the vacuum advance source from ported vacuum to full manifold vacuum.
