Two weeks ago my fresh 454 built by myself locked up on the first run after 45 min. of running time. I restarted it the next day and it seemed to run fine. I pulled it anyaways and found no problems except for the thrust area of the rear main. I brough it to the machine shop for a thourough tear down and they found nothing wrong. Polished the crank and put new bearings back in. (let them assemble this time) I never checked drive alignment when i put it back in but it slid right in place. What cou7ld have caused this? Note: the oil pressure never exceeded 40psi and i was leary about it from the start. The machine shop said everything was ok.

Define "locked-up"?

It couldn't have been locked-up/seized if it started the next day...could it?

Oil pressure does seem a bit low though. How does it run now?

As I was cruising at 3200rpm it started to loose power and i tried to give it more. Motor died and would not turn over to restart. Pulled all plugs and there was no sigh of any water. Let it cool down and it fired right up the next day. Ran smooth but had a squeal noise like the impellor was getting dry and ready to go bad. The noise was not the impellor. I pick it up from the machine shop today. The machine shop said I did nothing wrong with assembly and they could find nothing wrong except for the rear thrust side of the bearing. clearaces perfect, oil pump fine, no blocked passages. He put new bearings in and replaced the oil pump anyway. I will put the long block together myself.

What was wrong with the rear thrust bearing? I only ask because I'll be going through mine soon and plan on doing it myself as well..

Keep us posted... Good luck

The rear thrust bearing was worn into the brass/copper part of thr tri-metal construction. Only on the thrust area of the bearing.

Cheitman,
Did you check crankshaft endplay? Should be between .005-.007. If there isnt enough endplay I have seen them ruin the rear main and the thrust surface of the crankshaft. It probably restarted after the cool down process due to component contraction. Be sure to check the thrust surface of the crank before you reassemble to be sure it isnt blued or scored.
Bob

Could've been something other than mechanical, like fuel or ignition...

What were your engine temps? I'm wondering if you over heated it. I had a engine once that overheated because the thermostat stuck closed. It was running fine until it came to an idle where as it promptly stopped. The engine wouldn't turn over, the starter only clicked. About 20 minutes later the engine started and ran just fine. Also, if the engine is without water, the gauge will not show a high temp. It can't read air temperature, only water.

Endplay was and again is .006. Motor was running 150-160 and I checked manifolds immediately after the incident and they were cool to the touch.

Ring end gap?????