RV-12 Cowling intall - before or after

I am pondering whether to install the cowling before I install the engine/spinner or after. I would like to install it before but I want the fit to be right. Any feedback would be appreciated.

Covered thoroughly here, search is recommended. Advice consensus is fit with engine in place. Consider modifying the cowl for better spacing between oil cooler and muffler.

From my experience you want to do it with the engine and spinner in place.

I just moved the oil cooler ahead about one inch after test flying. Do yourself a favor and do it while building.

Forrest,

Do RV-12 Cowling after Engine and Spinner

The RV-12 cowling is a tight fit and will need to be put on and taken off many times before it is finished. I just completed mine and am so glad I installed the engine, muffler, and spinner first. The cowling is a lot of work, and I definitely would not recommend installing it first.

If I were doing my cowling again I would trim the pieces, sand the top and bottom insides, give the insides a coat of West 105 epoxy resin, install the piano hinges, then install the cooling duct. I had to modify my cooling duct to have adequate clearance around the cylinder 2 exhaust pipe spring.

Moving the oil cooler forward one inch takes some doing but is an elegant solution to the high oil temperature problem when flying in hot summer temperatures. Best to do this mod while installing the cooling duct so the oil cooler mount part can be cut out and moved forward before it is epoxied in place.

I had the same concern and fitted it with the engine installed. After all the worrying it turned out my cuts were right on the scribe lines. Having said that there is no issue with waiting until the engine is installed, and you avoid the risk of a random scribe error.