Ignition: vacuum advance?

[jbjr]

I have a 54 3R5 truck with a 259 V8 for the past few weeks it has been giving me trouble. In put a vacuum test on it and it showed 15 Hg which I believe is late timing. Today I put new plugs in it, timed the ignition and it dropped to 15Hg's again. Next I tried advancing the timing a little at a time and it went up to 19 Hg,s and dropped back to 15 Hg's. Could the vacuum advance be causing the problem? Thanks

[RadioRoy]

Have you put a vacuum pump on the vacuum advance unit and looked with a timing light to see if the vacuum advance is working?

[jbjr]

not as of yet, needed to put it up for the night and help the wife. I will try in the AM.

[doofus]

try plugging the vacuum line to the advance unit. if vacuum changes there is your problem. Luck Doofus

[jbjr]

tried plugging the line and nothing changed. Did another vacuum test after trying to reset the timing and it went up to 16hg's any suggestions?

[Mrs K Corbin]

Yeah, try the propane/Mapp gas trick to see if you've got a carb/intake leak.

[doofus]

Have you adjusted the valves lately? Luck Doofus

[jbjr]

I have not heard any valve tapping but will try the propane and then take a look at the valves. It might take a couple of days because other things need to be down first. thanks

[64studeavanti]

Have you tried adjusting idle screws. A poorly adjusted carb will affect vacuum at idle.

[jbjr]

Well I found the problem ,after looking at other things I decided to change the distributor cap with an spare that I had. The 2 nuts that attach the pick up coil to were no where to be seen and it was floating loose. I will pull the distributor in the morning and hopefully that will solve the problem. Thanks for all the input and help.

[altair]

My 259 idles about 19 inches