Help! Popping noise in rebuilt engine
 

Engine was completely rebuilt 1500 miles ago. All was fine, running smooth. Parked it for a week and now it has no power and a popping noise is coming from somewhere under the air cleaner canister. Valves?

What year? What engine? FI? Carbs? etc.

Is it affecting anything? Running OK otherwise?

It is a 1975 2.0 FI. It is not running right in any gear as there is no power. I shipped it by flatbed back to the shop that rebuilt it only to be getting the run around. We think a valve is bent or a valve seat. No compression. Something not right with only 1500 miles on the engine at the whopping cost of 8k. shop is trying to get out of fixing it and won't give a straight answer as to what is wrong with it. So done with this car.

Popping noice in 914 newly rebuilt engine
 

The popping noise ended up being a flat cam in a newly rebuilt engine with less than 1500 miles on it. The shop who built it fought me tooth and nail over fixing it but finally came thru after having the car 4 months. :(Unfortunately, when he gave it back it now runs too hot and will stall at every stop until you let it cool down. One disaster after another with this shop called Otto's.

Cam Failures caused by re-formulated Oils
 

Your not the only one to have this problem.

I personally put most of the blame on re-formulated oils that do not protect our flat lifter cars, especially air-cooled. The oil is the only thing that has changed with a couple of low mileage 911 engines I have torn down lately. At first I blamed it on the previous engine builder or parts. Nothing else changed except the oil.

914's had problems with cams even before the oil problems.

Check out this article:
http://www.hotrod.com/techarticles/engine/flat_tappet_cam_tech/index.html