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Cylinder Head and Exhaust Manifold Mismatch?

Started by Joe V, September 07, 2014, 07:37:26 PM

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Joe V

So I'm going over the engine in a 49 Series 62 with a fine tooth comb in an effort to identify anything that could be the cause of lack of power when you give it the gas.  It appears that whoever set the newly rebuilt engine in manufactured a filler plate due to a mismatched cylinder head and exhaust manifold - see picture of center exhaust outlet on passenger side.  Same filler plate exists on the driver side center outlet.  No filler plates on any other outlets.

Doesn't look right to me so I looked at exhaust manifolds on ebay and there is a break in the year with specific manifolds that fit a 49 and others that fit a 52 and later. Is it possible that the car has a 49 exhaust manifolds and 52 (or other year) heads, or vice versa? Or is the plate in the picture the correct configuration for a 49? 

Is there a difference in outlet configuration on a 49 exhaust manifold and cylinder head from one year to another?  Is there a source for number matching to see which year manifolds and heads the engine has?

John Washburn CLC 1067 Sadly deceased.

Joe,

The heads and exhaust manifolds are the same 1949 to 1951. Then in 1952 to 1955 the exhaust manifolds are the same. For the heads, Cadillac changed these to get more hp. But since the exhaust manifolds are the same it would seem that you have later heads with the 1949 exhaust manifolds. But that is just a guess based on your pictures. It was common to change to later heads if the older ones were cracked.

The Johnny
John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

Joe V

Thank you.  Probably a well placed guess since a larger exhaust port would seem to align with changes to increase HP as you have described.  I'll start watching the auctions for decent priced 52-55 manifolds. 

Jay Friedman

Joe,

As John said, it's most likely that you have 52-55 cylinder heads. 

You couldn't use 52-55 manifolds because they are for dual exhausts which Cadillacs had beginning in 52.  As such, the 52-55 manifolds will not have the opening necessary on the right hand (passenger's side) manifold for the crossover pipe of your 49.  Installing dual exhausts can be done on a 49, but it's not easy as you won't have all the holes in the frame, plus you'll run into fuel line issues as the new left side exhaust pipe will run close to the long fuel line from the tank as well as the brake hydraulic line. 

The center exhaust port opening on 52-55 manifolds is larger than on 49-51 manifolds, which is probably why that plate is there to somehow adapt the heads to the manifolds. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Joe V

When I look at the 52 manifolds with that information it is obviously different. I put the exhaust into the 49 and remember seeing that it could only go on one side. Not interested in cutting hols in the frame at this point.

So my options are to live with the filler plate or start looking for 49 heads. I'll defer that decision until I work through all other possible causes for the lack of power.

Thank you both so very much for the time and cost savings as a result of relaying lessons learned and knowledge.