timing trouble

[slamminsimon]

I have a 91 ford f-250 with the 302 and the tfi-4 ignition system. I resently took the engine out to change all the engine gaskets and then put it back in. After putting it back in and test driving it I noticed that after about half throttle I start to get spark knock and the engine shutters. In town when I am not giving it full throttle its fine. I checked the timing with a timing light and it was according to spec. I changed the tps but it had no effect. Anybody had this problem before? Any input would be great. THANKS

[rhandwor]

Did you disconnect the spout when you set the timing?

[slamminsimon]

Are you talking about the vacume advance?

[rhandwor]

As far as I know a Ford this new doesn't have a vacuum advance. The spout is a plug located near the TFI module. You disconnect this plug to set the timing. When done you reconnect the spout. Otherwise the computer is always moving the timing and it is impossible to set correctly.

[jfberry]

I am having the same issue. I have a 94 with a 302. I did unplug the spout and checked the timing. I am at my witts end trying to find this miss. New plugs, rotar button and distributar cap. Any help would be great. If I run high test with an octane booster it helps but still pings and misses

[rhandwor]

I would suspect that the timing chain is stretched. Try spraying carburator cleaner around the intake manifold and any vacuum hoses if it hits a leak it will smooth right out. To check the timing chain roll the engine by using a socket wrench to appx. 60 degrees past top dead center. Then turn it back to zero degrees. Use white out and mark a place on top of the distributor base even with the rotor. Have somebody watch the rotor turn it by hand until the person watching says the rotor started to move. Look at the timing mark anything over 20 degrees is approaching excessive slop.
Labor intensive but not a very expensive job. Most parts stores carry a two piece timing set with gasket.

[jfberry]

Thanks for the great info. I have alot of time on my hands and very little money so this should workout great!