1929 intake manifolds - Cad or "LaS" embossment?

[m-mman]

1929 341B intake manifold.

The authenticity manual shows that the Cadillacs had a tin engine cover with "Cadillac V-8" on it. (missing on my car) Currently there is a round cover in the center of the intake manifold that has a big "LaS" embossed in it. My car is original enough that I think it might have come that way.

Question: Did all 1928-9 cars have the "LaS" on the manifold (to be hidden with the Cadillac cover?) or were the Cads built with a blank plate?

And I gotta ask, does anyone happen to have a spare "Cadillac V-8" cover? 

[31caddy]

Cadillacs had the tin cover and a plain round plate on the intake manifold itself. LaSalles had no tin cover, but had the embossed plate on the intake like the one you have. I have parted out and restored several '30/'31 Cadillac's and it is very common for the intake manifolds to crack or "blow out" around the exhaust cross over area. Often the ones I find as loose parts are no good because of this. For this reason, I have block off plates on the exhaust manifold cross over ports on my 31. The tin cover hides the block off plates.  The '29 intake is very similar, but does not have the same boss for the spark advance linkage. I suspect that somewhere  in your car's history, the manifold was changed due to cracking, or someone simply liked the LaSalle cover and installed that. Not sure about '29, but in the 30/31 model years I have also seen varying bolt patterns used to hold the circular plate to the intake - some had more bolts than others. So, it's also possible that your intake was changed, and they couldn't reuse the plain Cadillac round plate because of this issue. I have sold several original tin covers, and usually get $500-600 for one, but I don't have any spares at the moment. Mike at International Restorations (google it) in Oak Park, Ill reproduces them, and I believe around $500 is what he gets for one. These covers are very often missing because they can be a small pain in the neck to remove/install. Mechanics/owners simply threw them away. The same is true for engine splash pans which can be very difficult to locate.

[m-mman]

OMG - a burned out manifold . . . . why didn't I think of that?   

So, I am about to clean up and bolt the manifold to my new engine and now I figure I should take it apart and look at it. 
Gee whiz what a piece of engineering(!) An aluminum chamber caring exhaust gasses . . . I guess they had to heat up the poorly refined sludge they called fuel 90 years ago before it would burn.

Yeah, after looking at it I think I need to make block off plates too. Thanks for the suggestion. 
Boy, these things are just not built with 1950s & 60s engineering 

I guess the engine cover will have to wait. But thankfully I DO have both the splash pans 

[31caddy]

Whooaahh. It should be painfully obvious if your manifold is bad. Usually any cracks are readily apparent on the outside. The ones that "blow out" lose a big chunk on the raised portion of the aluminum right above the crossover tube. If it looks good externally, you are probably fine.
Many more modern V8's have exhaust cross overs running through aluminum intakes. I think the problem with this design is the different expansion rates of the steel tube/nut and the aluminum manifold combined with the age/questionable quality of the aluminum casting. All of the cracks/ missing pieces I have seen are in that area adjacent to the steel nut.

[m-mman]

Mine looks solid and there are no cracks.   

When you blocked off the exhaust crossover,did you just put a plate between the exhaust manifold and the crossover or did you remove the steel pipes that are screwed into the intake?
Looking at how those things are screwed into the aluminum, they look like they would be happier if they were left alone. 

[31caddy]

You're exactly right about leaving the big nuts alone in the intake. I doubt if you can get them loose anyway. I have block off plates on the exhaust manifolds and I don't even have any cross over tubes anymore. They were cut off, and the big nuts remain in the intake.  All of this is covered by the tin cover anyway. Often the tubes themselves are rotten. If yours are good, perhaps you could weld up the flanges that bolt to the exhaust manifolds on the inside of the flanges. I'm thinking a thick washer or a round metal plate inserted into the flange and welded up such that a stock appearance is maintained. I suggest this because you will find it impossible to insert an adequate block off plate along with gaskets between the existing cross over tube flange and the exhaust manifold. The fit is just too close. It is hard enough sometimes just to get the stock gasket in there.
Also, if everything is in fine shape, perhaps you should simply reinstall it and run it. ( If it ain't broke, don't fix it ) It may last many more years. If it concerns you that it will be a future problem, you could just be on the look out for a spare intake. Good luck.