You almost don't need to know specs to check it out -- with the vacuum hose to the distrib off, the advance should move 15 - 20 degrees more advanced when you rev it from idle (750 say) to 2500. If it moves smoothly with RPMs it's "working". Vacuum, at idle with the hose off it should be 5 - 10 btdc whatever the book says. When you put manifold vacuum on it (16 - 19 inHg or so) timing should jump 15 - 20 degrees more advance. Simple. There are dual diaphragm units with vacuum retard for some apps. Never actaully worked with one. On Sun, Jun 6, 2010 at 9:37 PM, <das24rules@xxxxxxxxx> wrote: > this engine is supposed to have been a rebuilt short block. re-used dizzy, > and > it had metal shavings in the bottom of the cap area and bearings were wore > out > on it. i got an oem replacement from local auto parts outlet > (shucks-orielly) > and im just wondering. do those big early electronic dizzy's have > mechanical > advance on them? if so, i would assume it would be different for car and > trucks. i wonder if i got given a car dizzy that could be putting the > advance > in to late, making it retarded under light load. i have a timing light, and > checked it when i dropped the new dizzy in it. i dont know what the heck it > is supposed to be at for this engine with no load at what rpms. i know late > timing can cause heat, but it dont make any sense to me that it would build > lots of heat under NO load, but be perfecly normal under HEAVY load. > dave stohler > www.picasaweb.google.com/das24rules > _______________________________________________ > AMC-list mailing list > AMC-list@xxxxxxxxxxxx > http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://list.amc-list.com/pipermail/amc-list-amc-list.com/attachments/20100606/4c34f718/attachment.htm> _______________________________________________ AMC-list mailing list AMC-list@xxxxxxxxxxxx http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com