all right I got my carb rebuilt and had no problems there but I was wondering where is the vac advance line suppose to hook up to ported vac on the carb or straight manifold vac? I've been told both ways. and I've tried both ways when its hooked to the manifold the engine idles smoother and responds to the throttle better. which way is the correct way. also what is the timing supposed to be on a 79 300 six there is no label on the truck anyhwhere.

I know when setting the timming you are supposed to disconnect the vac advance line and plug it then set the timing this makes sense if the vac advance is hooked to the manifold because it has vac all the time at idle. but if the vac advance is supposed to be hooked to ported carb vacuum it does not have vac untill the throttle is cracked and even then I've never seen the vac advance move when I crack the throttle or rev the engine.

sorry for all these newbie questions I have been a diesel mechanic for 8 years but I never worked on gas engines at all. infact I have never even owned a carburated engine until I bought this 79. my theory was if it has spark plugs in it I don't work on it. maybe I should stick to that theory

 

The correct way is whichever way it works.

For timing, use a vacuum gauge on a full vac port. Advance the dizzy until the highest, steady reading is achieved and then back off 1-2 hg. Drive and try. Readjust if necessary.