Get a timing light out and check vacuum advance and mechanical advance, separately. Timing and carb issues can seem similar sometimes, and spark timing is easy to measure! Going up a hill with load means low vacuum means less spark advance. Late timing usually means heat-into-the-head and out the pipe but if you have fouled up timing or something else (timing chain issue?) it could make no sense. I wouldn't worry about the carb until spark is sorted. On Sat, Jun 5, 2010 at 8:36 PM, <das24rules@xxxxxxxxx> wrote: > so, my work truck ('77 ford f250 4x4) has a strange heating issue. when no > or > light load, it heats up. idling, or cruising down flat highway at 60mph. it > gets quite hot. if im going up a good hill, or pulling my trailer, it stays > right at 180*. it is a modified block. i think 351m not 400. has edelbrock > intake, edelbrock carb, new distributor (factory ford electronic). it also > doesnt feel like the secondary valves are working on the carb. you cant > feel > anything when you put your foot into it. it has a stiffer spring on > secondaries so you can feel when you get into them on the foot, motor makes > o > difference. i stay out of them all i can. it gets a whopping 8mpg too. the > heating issue has me just baffled. > _______________________________________________ > 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/aa130435/attachment.htm> _______________________________________________ AMC-list mailing list AMC-list@xxxxxxxxxxxx http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com