Cliff
03-14-2003, 02:15 PM
Had a pinging problem with the ole' 360 (rare problem for us FSJ'ers - right!) and after giving up, took it to my trusty mechanic. It took him 30 minutes to figure it out.
Basically, my timing was advancing way too far during acceleration, even though it was set properly at idle. This is caused by one of two things, or a combination of things.
1. the thermal and vacuum switches that litter our engine compartments actually have a purpose. Even though we all (most) remove them, they do limit the timing advance. Often this degrades performance, but in some cases, can also limit detonation.
2. Older engines develop wear within the distributor, like advance mechanisms and springs. This may allow timing to advance more than it should, resuting in detonation.
360 timing should be 38-42 degrees full advance (mechanical advance plus vacuum advance) at 2500rpm. Mine was pushing 60 degrees. The quick fix was to simply disconnect the vacuum advance. The Waggie runs great! However, it is recommended that I take the dizzy to a machine shop and have the unit "curved" on a machine to factory specs, using only the mechanical advance. This is a common practice with race cars, and a breeze for machine shops with a distributor machine. The Duraspark dizzy does not have an adjustable vacuum advance, and nobody makes an aftermarket unit for the AMC. The one for Fords does not fit the AMC version.
Hope this helps someone out there.
[ March 14, 2003, 09:16 PM: Message edited by: Cliff ]
Basically, my timing was advancing way too far during acceleration, even though it was set properly at idle. This is caused by one of two things, or a combination of things.
1. the thermal and vacuum switches that litter our engine compartments actually have a purpose. Even though we all (most) remove them, they do limit the timing advance. Often this degrades performance, but in some cases, can also limit detonation.
2. Older engines develop wear within the distributor, like advance mechanisms and springs. This may allow timing to advance more than it should, resuting in detonation.
360 timing should be 38-42 degrees full advance (mechanical advance plus vacuum advance) at 2500rpm. Mine was pushing 60 degrees. The quick fix was to simply disconnect the vacuum advance. The Waggie runs great! However, it is recommended that I take the dizzy to a machine shop and have the unit "curved" on a machine to factory specs, using only the mechanical advance. This is a common practice with race cars, and a breeze for machine shops with a distributor machine. The Duraspark dizzy does not have an adjustable vacuum advance, and nobody makes an aftermarket unit for the AMC. The one for Fords does not fit the AMC version.
Hope this helps someone out there.
[ March 14, 2003, 09:16 PM: Message edited by: Cliff ]