Attempting Intake Manifold removal/install 1971 400

[HottRubber351m]

Bought a 1954 Merc M10. I bought it as a late life perk. Guess I expected a turn key daily driver. Got fooled by the seller, but that's my bad. As I chase one thing after the other, my current issue is oil sitting in the dizzy recess and "sprayed" about the engine bay. Took out the distributor, checked for buggered O ring. Looked brand new. Replaced it anyway. Got it running again and test drove. Still oil leak. Pretty sure I saw a small stream coming from the front China Wall of the intake manifold. Makes kinda sense cause there's a bead of bubbled red RTV along this area. I assume this was a previous issue that was poorly addressed. I was told and who knows, this was a rebuilt 1983 351W. Casting marks on the block indicate a 1971 400. I realize that a rebuild could have several different vintage parts. The Casting mark on the Intake has the "kiss of death" MCC marking. But if its a rebuild I'm hoping my worries are unwarranted.

Anyway I'm going to remove the In Man. I'm nervous as hell. I've never done anything like this before. Firstly, should I do this considering the year? I think so. What are the alternatives? Not really looking for an answer to that .

I assume I have to remove the dizzy, the water neck and upper rad hose, carburetor and any other wires and hoses that get in the way? I'll take the hood off too for easier access. The In Man looks heavy. I have an overhead winch. I could use that. Are there lifting points on the manifold?. So I carefully take this thing off, cause I've read the china walls are, well like china. Scrape all the old gasket and RTV off. I've read conflicting info about replacing the gasket as opposed to just using RTV? Also read about using front and back rubber "corner brackets" or not? What's the consensus on a really good sealant product?. So in my mind I seal up the bottom of the manifold, let it set up and then lower it onto the block. What's to stop all the goop from shifting out of place while maneuvering the heavy manifold into position? Then re-bolt and torque to spec following the sequence.

Oh yah, just to back up...what am I looking for when I remove the intake? Will I be able to see cracks, imperfections in the decking?

Sorry for barfing this all out. Feels good to get it all written down. Any and all help will be greatly appreciated.

[Fraser]

M block intake manifolds commonly leak oil in that area, get it super clean and use silicon under the tin gasket. You can now get a fiber gasket instead of the tin one, that's what I'll use next time.
The casting marks do not change by year, only way to know is by the stroke and date stamp. Look for the casting mark at the top rear of the block, beside the oil sender, the one on the manifold doesn't matter My '77 had the wrong block, however it stood up fine, so don't be concerned if it is a Michigan block, if it hasn't cracked yet it probably wont. When you have the manifold off, look for clean spots at the very ends of the lifter gallery, a crack will not be easily visible, but the escaping steam will steam clean the area around the crack.
The early blocks were all Cleveland, I think Michigan started in '76, and the problem was corrected in march of '77, so not a lot of bad ones were made.
Most of this is just from memory, but somewhere there is a website with everything you ever did or did not want to know about M block engines, it may bore you to tears.

I wont say you have to change the manifold and carb to a 4V, but they sure wake up a 400.

[HottRubber351m]

Thanks you. Know how I can lift it off with overhead? Too old to muscle it out

[Fraser]

You will have to pop it free with a pry bar first, then it's really not that heavy, just awkward to reach. Just a ratchet strap around the carb base, or onto the studs should work. You can buy a carb plate lifter which will lift the whole engine, but that's overkill.

The only time I was ever able to really get a good seal on that engine, I threw away those rubber seals and just used silicon, but that was 30 years ago, hopefully the new seals are better now, And I have no idea why. but there is more than one type of tin gasket, the last one I used did not sit into the opening correctly, so I had to try another, both were Felpro, but different numbers. This is a job I need to do on my '77, but it will have to wait for now, too many other irons in the fire.

[HottRubber351m]

Good to know. Thank sir