09-21-10, 11:45 PM
Hi, I have a 69 DeVille and the prior owner had the engine rebuilt 700 miles ago due to the engine overheating - new pistons/rings, bearings, cam, lifters, bored out, hardened valve seats, new oil pump, new water pump - I have the receipts and talked to the guy who did the job and believe that all of this was done. Sounds good...... but, I have two problems: 1) about half the time I start the engine, I have a very distinct, loud, single tap tap tap tap. After anywhere from 15 seconds to a couple of minutes, it goes away - althought it faintly comes and goes sometimes. 2) under more than light acceleration I get what seems to be a moderate multiple tap or valve noise. The engine starts (and stops) great, acceleration is good, it idles steady (with point/condensor), timing is 5btdc, mechanical and vacuum advance are working properly, engine oil is 10-30 and is less than 200 miles old with a new filter, and the car was not driven hard the first 500 miles after engine rebuild. I put a container of CD3 (extra engine oil detergent) in the oil to help clean out any potential gunk that may have somehow gotten into a lifter and cause the tap tap tap. I've also been using 93 octane and recently put some octane boost in to see if the acceleration noise was engine knock, but I did not notice any difference after adding it (it didn't sound much like engine knock anyway). Hmmm. Suggestions on what's going on? Thanks!