Plate under the intake's purpose

[1960BreadTruck]

Hey ya'll, so I'm rebuilding my grandad's old 69' 351W, and just popped the intake off. Riveted to the bottom of the intake is stamped steel plate with hole in it (for drainage I assume). As I'm trying to clean the intake out, I keep getting big chunks of carbon crap out from under that plate. Curiosity and the sake of cleanliness lead me to remove that plate, with the assumption it could be put back on with use of screws, need be. Under the plate hid a chunk of crap the size of my palm, and a plug in the bottom of the intake that I'm not about to attempt to remove. My question is: What the heck is that plate for??? Does it need to be there? Thanks in advance, I'll post up more pics of the rebuild as it comes along!

 

[KULTULZ]

The purpose of the shield is to hopefully prevent exactly what you found. It protects the bottom of the intake casting from oil splash from the engine lifter valley.

If the CCV is not functioning properly the splash will solidify of the bottom of the intake and possibly fall and contaminate the engine oil with solids.

Notice it is directly under the manifold heat crossover. That buildup will also cause excessive heat buildup directly under that crossover and will not allow the carb pad to cool properly (heat soak).

FORGET TO ANSWER -

Under the plate hid a chunk of crap the size of my palm, and a plug in the bottom of the intake ...

That plug was used to empty casting sand out of the manifold casting. No need to disturb.

 

[1960BreadTruck]

Okidoke, thank you! I'll drill out the rivets and get that plate back on

 

[1960BreadTruck]

Well the plate is back on, here is a picture of the forbidden portion of the intake. More to come!

 

[dmsfrr]

IF... the exhaust on the engine has a heat actuated control valve on one side it may be sticking shut. Forcing exhaust thru the exh crossover passage inside the intake manifold all the time, overheating it. If the car has dual exhaust and one side is partially blocked it would have the same effect.

I'm not familiar with the original '69 exhaust setup. Had a '71 Merc with a 302w back in the day but it had headers.

These example photos are parts off of a '57, possibly similar to what you may have. ???
.

 

[KULTULZ]

if... The exhaust on the engine has a heat actuated control valve on one side it may be sticking shut. Forcing exhaust thru the exh crossover passage inside the intake manifold all the time, overheating it. If the car has dual exhaust and one side is partially blocked it would have the same effect.

- Good Point! -​