Truck keeps getting out of timing

[Skunksmash]

Well, it has been a while and the truck has still not walked its way out of time. On the day that we went ahead and changed the timing chain (he wanted to do it anyway) we reseated (for the umpteenth time) the dizzy and re timed it. I guess that maybe the chain was stretched?  Usually, by this time, the truck would be running quite badly and getting to be undrivable.

[4x4orbust]

the centrifical advance weights might be sticking
take off the rotor and make sure the weights are not flopping around or binding/sticking

check the vacuum advance cannister with a mityvac
http://www.ronshomeandhardware.com/ProductDetails.asp?ProductCode=188870&click=1014

small threadjack here.....

how would you test the vac advance canister with a mityvac?   i just happen to have one, when you apply vacuum to the canister, should the vacuum remain constant or slowly dwindle to nothing?

[eventhorizon66]

small threadjack here.....

how would you test the vac advance canister with a mityvac?   i just happen to have one, when you apply vacuum to the canister, should the vacuum remain constant or slowly dwindle to nothing?

You would apply vacuum to the advance canister with a timing light hooked up and the engine idling.  If it's working, you should be able to observe the timing advancing.  If you have an advance timing light you could measure how much it is advancing the timing.  And if you had a vacuum gauage tee'd in you could measure the vacuum level where it reaches max advance.

[DnStClr]

eventhorizon66- you had me goin with that post about the DOHC lol.I had to reread his 1st post to see what Imissed!  Good one.