Quote Originally Posted by johnnyd
I brought the cleanest 1990 f-350 4x4 Lariat home tonight that south Texas had to offer.

In all my earlier 77-79 460 trucks I installed an early model straight up timing gear. Is this still a good idea with the later model fuel injected motors? Computers? Pros and cons?

The truck has 100K, no smoke or blowby, auto trans w/od, 200 amp alternator, and what sure feels like 4.10 gears.

Thanks for any info, sources etc

John D. De Paolo
JohnnyD,

The 1990 460FI motor already comes from the factory with a roller timing chain that is installed straight up and not retarded like the late model carbed engines. The OBD1 computer takes care of the emmissions.

In regards to changing it anyway, what you need to do is check for timing chain stretch. Remove the distributor cap and watch the rotor while turning the crank pulley. Once the rotor turns, stop turning the crank pulley and try going the other way...and see how far the crankshaft may be turned before the distributor rotor also turns. More than 3-degrees of crank rotation and it's time to change the timing chain. IF you cannot see the rotor turning (because the distributor is at the back of the engine) then have a friend watch and tell you when it turns. Then, mark the location of the crank and turn it the other way until your buddy tells you again that the dizzy is turning.

But I doubt your timing chain needs changing; a friend of mine has a 1991 F250 and his waterpump went out at 444,000 miles. Since he was already changing the waterpump, he decided to pull the front cover and do the timing chain at the same time. What he found was that the oem chain was still perfectly tight. Last I heard, he has 500,000 miles on the truck.

Paul