What have you guys done? Engine is complete older rebuild with low miles but bad prep on engine and no primer. paint is pealing badly. no leaks. I have block offs for all passages. that I have used in the past but this thing needs more attention than the others I have redone. I thought about blasting the thing but would have to be extremely careful on the sealing of it.any ideas?? ozz

Most engine don't get primer - paint buildup gets too heavy then it flakes off from the heat.

I think with the engine together you're pretty much screwed as far as giving it any sort of cleaning that will produce a good, lasting finish. Maybe go at it with a wire wheel and then some brake cleaner and a couple light coats of engine enamel.

lurking nearby by for more tips...I'm in same boat as O.P., so keep those voices of experience coming, thanks

Oven cleaner helps with grease and with loose paint, then I use 409 to kill the remaining grease. I've also had good results spraying pump gas over the entire engine to dry oily gunk.

well Ive sealed every thing up. with plates on the exhaust rubber plugs and or caps every where else. plated the carb opening and sealed.then for extra protection a little duct tape in places. cut off an old distributor and fuel pump and made block offs for those spots going to let the silicone dry over night and going to blast in the morning. I always have primed my motors with high temp seems like when I didnt that is when it tried to come off. I'll hope for the best and let you know how it turns out. ozz

oven cleaner,, and 409 work great ,
when it did it also used mineral spirts
for a final wash, '
let dry, i did use a engine primer ,
that was 1998 paint still looks good with no peal

Chasing any moisture out of the metal with a propane torch right before painting seems to help adhesion too.

after most of the grime is already removed I like using a bunch of acetone to wash and wipe it all down really well, do it until the wipes stay white.