I just got my 396 back from the machine shop. Its ready to be re-assembled, but I thought I would ask how best to paint it. One part at a time or as an assembled unit? Not sure how it was done at factory.

Also, did they paint over the freeze plugs?

Was painted assembled at the factory with bell housing, intake and exhaust nanifolds.

Cool, thanks for the quick reply.

People are painting their engines and putting overspray on the chrome in huge amounts. I have original pictures of our cars engines and a friends engine when the cars were new. While the picture quality is not the greatest, no overspray is obvious. If there was any it was minimal at best. GM used masks and any overspray would be due to an ill fitting mask allowing a mist here and there to waft up onto the valve covers. Perhaps, on occasion, some factory guys did freehand the job and make a mess but I have never seen it myself. I don't recall ever seeing the amount of overspray that some of these restorations have. They used to mask the Chev and GMC tailgates to paint the lettering back in the earlier '80s. Those masks used to give us fits trying to keep them fitting tight so as to keep paint from misting up under the edges. GM eventually went to decals and eliminated a lot of headaches. Paint masks are a pain.
I tried Por15 on a cast iron intake and wouldn't hesitate to use it on the whole engine. Looked great to me and people who have used it claim that it is very durable....if done properly.

I'm a detail freak and just couldn't overspray my aluminum intake or bell housing like concourse cars do. I would mount the motor on a stand, build the bottom end, and get the pan and heads on. Then you should clean the block so the paint will stick. I like to blow a cup of lacquer thinner through my paint gun on it starting from the top to clean it. I to like the POR-15 products and would use them.

I've been painting mine one piece at a time, but it's a pain and the masking is taking a long time. It looks really good though, and I think it'll look awsome when assembled like that.