Technical 365/390 exhaust manifold

I have a 55 Cadillac that someone put a 1958 365 engine with 390 heads in it. What years 56 to ? will the manifold swap from the passenger side to the drivers side. In 1955 they used the center exit to clear the steering and breaks. I have a 331 manifold but the ports are too small.

 

btt

 

Will a set from a '58 not work? The pass side and drivers side of a '58 are shaped differently. Here's some pics, they are available for around $100 apiece. Not bad, but maybe I am missing something, like clearance to the steering and brakes in your situation. If that's the case could you use headers instead and modify? Never heard of a Caddy manifold being interchangeable from pass to driver, but no one has ever labeled me very bright.

 

Thanks for the bump Jalopy Joker.

Clunker, I was talking to a local guy with a Cadillac and told him that the previous owner left the 331 manifold on the drivers side which is why it sat in a barn since 1971. He told me to just use a manifold from the passenger side of a 365 or 390. I hate to throw out 100 bucks to find out it wont work.. I figured I could find one local to me to try if I know what all years to look for. Or get info from someone that has already installed a 365/390 in a 55. Hopefully I will have this thing ready to drive to the Hamb drags next year.

 

The exhaust manifolds exchange from one side to the other on the engine, don't know about in the car. All of my 49-62 Caddy engines in hot rods, I use the left side manifolds on both sides. The size of the exhaust ports and the bolt spacing vary through the years.

 

So you use a left side manifold on both sides so the flange is centered and points down, then fab the pipes to fit the details of the specific car, since it's usually not a Caddy. But you stick to manifold from the same year, or one you know is compatible. Is that right?

So maybe he wants to know which year left side manifolds will fit a '58 so he can do just that. But would that not put the exhaust pipe from the manifold side that was originally swept back on a collision course with whatever it was trying to avoid by being swept back, since it's in a similar engine bay? ( '55 and '58 Caddys engine bays don't seem that radically different)

 

I also have this question; wouldn't a '58 365 in a '58 car require fabbing a custom exhaust, or at least modding a stock exhaust? If so, would it not be a good solution to buy something like this and fab headers and an exhaust to fit the car? This might be a stupid question, so forgive me ahead of time, I've not done this kind of swap.

 

cad-lasalle,
that is the information I am looking for. Did they change in 63? Should I only look for 56 to 62 passenger side. The driver side of a 68 exits out the rear of the manifold and would hit the master cylinder and linkage of a 55. The master cylinder is not up on the fire wall.

clunker,
"So you use a left side manifold on both sides so the flange is centered and points down"
That is correct.
My 55 exhaust exits in the middle on both sides as it came with the original 331 to clear everything but a 331 manifold wont fit a 365/390 head.

 

I don't know about '63. I've only used 49- 62 engines. I think a friend of mine used a 429 (64-67) manifold on a 58 365, but in a hot rod.