I have a rebuilt 455 with less than 400 miles. It has an apparant noise probably a knock in the engine on startup. It lasts until the pump develops pressure about 3 seconds or so. Once it is running the engine has no other nocking noise. Also the rocker arms rattle upon a heavy acceleration. I had to moderately accelerate once. Maybe also oil related... I haven't spun the engine over 2300 or so... so I dont know quite how bad the rocker arm issue is... My oil pressure is around 21 psi at hot idle and 50 on cold start. 10w-40 oil. The engine doesn't knock unless it has set for a couple of hours. I have changed the oil filter 3 times since it has been started. 2 ac filters and 1 napa gold filter. The shortblock was assembled by a knowledgeable buick builder along with a rebuilt front cover and pump assembly. Where would be a good place to start looking.. I hope to have provided enough information ... Thanks. Alan Wilson
Is it a knock or lifter clatter. Lifter noise on start up is not uncommon on Buicks. You may need adjustible push rods. John
Start-up Hey, I had a small problem like this on a motor that I rebuilt. I checked everything. Then on a street incounter it stated knocking. I tore it down to find that the oil pick-up screen was covered over. The shop rages had left small amounts lint all through engine as had rebuilt it. If nothing else shows up iwould check and see how long it takes for the pressure to build. Make sure you're not using a fram oil filter.
