I'm almost finished assembling the 400 for my 69. What sealant, if any, do you guys use on the rubber seal that goes between the front of the intake manifold and the rear of the timing cover? Also, what do you recommend using to clean the engine before I paint it? It's in bare cast iron right now. I'm not painting it until after it comes off of the dyno. Thank you.
Typically you don't need a sealant, but I assume any of the RTV/Gasket makers will work. Keep the intake loose, torque down the long water pump bolt to draw the intake to the rubber O-ring to seal it, then tighten/torque the intake.
Not sure on a cleaner. Maybe something simple like Spic & Span or other soap that will get the oils off and not leave any residue prior to painting. I found this neat write up that may be of some help:
"If you have old paint on the engine, use Easy Off oven cleaner to remove paint. I seal everything up really good with plastic bags and duct tape, etc... Spray it with the oven cleaner, let it sit 20-30 minutes. If needed, cover the sprayed areas with plastic to prevent the oven cleaner from flashing off too quickly. Next, I use a pressure washer to thoroughly clean the outside. The old enamel paint will come right off.
Once most of the paint is off, then use soap and water (make sure there is no silicone in soap) and a scrub brush to clean it. Rinse thoroughly and then air dry with compressed air.
Once clean and dry, I spray the block with an epoxy primer. Epoxy does not have pores in it, so you will not have problems with the paint flaking off that you will have with enamel. Once you have a couple of even coats of epoxy, you can paint with the color of your choice. You can use the rattle can enamel or you can use a base coat/clear coat.
This will give you a long lasting paint job! Thorough cleaning and epoxy are the key.
When masking the block to cover areas not to be sprayed aluminum foil works great.
Take a small hammer to tap the foil around the edges as this will make a perfect and clean cut on the foil making for a PERFECT masking job around the edges!"