do I need to time engine

you should not have to if it is done right. is it running good?

Yes. What do you mean if its done right? The only way to put one back with the same timing is ti mark it. But you cant mark a distributor that has never been in the vehicle. You can get it close but at least check it. I dont even change a cap without checking timing. The only way id say not to is if there is no adjustment what so ever.

I have pulled many distributors and never had to adjust timing I make sure of TDC then look at rotor button Put cap back on and put #1wire in the right place and they have slways cranked right up The only time it did not is when it was 180 degrees out

They will crank and you may not notice. But it usually isnt spot on. I can do it without too, but its not the RIGHT way. Just like the RIGHT way to tighten lugs is with a torque wrench. I just assume any poster in this site knows little to nothing so i can make sure they know what they need to know.

Yeah your right

Thanks Guys. I have (2) 350s in my houseboat and was looking for an excuse to buy a timing light anyway!! LOL BACK TO THE TRUCK the real reason I asked is that I am more technical than mechanical. I replaced the ditributor without disconnecting the batt. I fired the the engine up and it ran odd for 5-10 seconds. Than ran the normal cold start cycle - meaning high idle and then low idle. I thought maybe the system self timed since it has a crank sensor and distributor sensor. BTW the truck is a 5.0, 1995 F150 4x4. Thanks again guys!!!

Also... When I replaced the distributor everything lined up, as good as possible... Not like the rotor and cap and wires got messed...

Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark

Since it's fuel injected it will be able to compensate. But they make a specific timing spec so it can have the optimal range to advance or retard as it sees fit.

Thanks Again Andrew!!! Found it: Warm engine, 10 deg BTDC with a wire diconnected. I expect this wire controls the timing automaticly. The beast is running good so far. I will pick up the timing light and practice on my 1980s 350 chevy 270hp in the old houseboat first. Then check the truck if I feel brave!!!