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Replacing CD 150 in '69 Alpine

Shannon Boal

Platinum Level Sponsor
I have added a "ported" vacuum source to a carb that had none by drilling in the manner you propose. Used a piece of 3/16" brake line, drilled for an interference fit of maybe 0.0008", drove it in with a tiny ball pein hammer. It worked fine....
[However, I've decided that the homemade vacuum port would be easy (even if wrong) and easily remedied with a dab of JB, so it will probably be at the head of the list of possible actions to take.]
 

Bill Blue

Platinum Level Sponsor
So here is my brake line after being wrapped a third of the way round a 7/8" socket and inserted into the wall of the carb. The hole should have been drilled 2 thou under size, but is slightly over size, so it is being held in place with Locktite "Red".

Second photo is of the inside of the carb. The white object is the brass throttle plate, which the flash did a number on.

IMG_8095.JPG IMG_8100.JPG

I was able to neck he tubing down enough to produce an orifice of about 1/16".

Bill
 

Barry

Diamond Level Sponsor
Bill,

That looks like it ought to work. About how far "in front of" the edge of the closed throttle plate is the orifice located?
 

Bill Blue

Platinum Level Sponsor
The adapters are finished. I had to make two of them, one to adapt the manifold to a flat plate and one to adapt the carb to a flat plate. The flat plates are then bolted together. The job has been rather involved. I bored the intake manifold throat from 1 1/2" to 1 25/32. That's a 1 /32" over 1 3/4" and about 1/8" over what the manifold should be bored to. Ran into bolt holes to bolt the manifold flat onto the exhaust manifold. Also broke through the casting, leaving a hole about 3/8" wide and going about a quarter of the way around the casting. I repaired the hole by making a temporary plug to fit into the throat. Plastic film was stretched around the plug and inserted into the throat. The hole was then filled with JB weld and plug removed. That gave me a manifold that was air tight but with little structural strength. That was solved by making manifold nuts about 3" long. They extend to the carb mounting surface and are bolted to the adapter plates. The whole mess will be virtually invisible after installation. The job is almost done, I'm starting on the control cables. I'm hoping it will all be worth while.
Bill
 

Gordon Holsinger

Diamond Level Sponsor
Except the actual port (the brass fitting) has at least two other air sources. One is a port subject to intake air flow on the far end of the carb. The other source(s) is currently unknown to me, but I can hear air sucking. So I doubt it experiences manifold vacuum when the throttle is closed. I can post a pic of the second air source if that would be of value.

Bill
A mechanic friend showed me how to spot a vacuum leak using a spray can of card cleaner he used a light squirt of carb cleaner near where the leak was suspected at idle the engine will do a little stumble and speed up.
 

Bill Blue

Platinum Level Sponsor
Different orientation of the carbs. SS and CD150. Not the adapter on the intake side of the 150 is misaligned, effectively reducing the intake air flow.
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Shot the long manifold nut. You can also see a bit of the JB Weld patch.
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Bill
 

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260Alpine

Silver Level Sponsor
Bill, A couple things I found looking up info on the S&S carb. The three threaded holes on top are for bolting the air cleaner on, the other hole is the vent for the fuel bowl and should not be covered up. I would jet between the middle and richest. if you are too lean or rich you can tell by where the idle mixture screw ends up. Should be between 1 1/4 and 1 3/4 to be in the ballpark.
 

Shannon Boal

Platinum Level Sponsor
I ran some numbers, cross-sectional area of carb throttle bores. Single S&S 1-7/8" about 2.8 "squared. 32/36 mm Weber DGV about 2.75" squared. The Zenith-Stromberg dual pair CD 1.5" are a lot more at 3.5" squared (but I am not a fan....) What do the numbers mean? Bill is probably gonna have a winner here.....could be a world-beater!
 

Bill Blue

Platinum Level Sponsor
Well, I have a single 150 Strom, so that figures out to be 1.75" square, making the S&S more than 50% larger. I'm going to find out if the problem is lack of carburetion, that's for sure.
I also corrected some manufacturing problems. The manifold ports were machined only about 1/8" deep, leaving casting flash on two of the ports. Also cleaned up the throat to log transition. So overall, performance should be improved.

As to mounting adaption, lets just say it is the only way I could see to mount the damn thing.
Bill
 

Shannon Boal

Platinum Level Sponsor
I can appreciate that.....only other option I see is Tig Welding fabricated adapter in place. How did you bore that big hole? As to mounting adaption, lets just say it is the only way I could see to mount the damn thing.
Bill[/QUOTE]
 

Bill Blue

Platinum Level Sponsor
Tig welding is for guys that can weld, not for me. So I spend a lot of time fabricating using bolts, screws and steel pop rivets. I bored the big hole using the thing I call my vertical mill. Except it is not really a vertical mill, more like an unholy cross of a vertical mill and boring machine. The thing works good for me, but is not as solid as a real vertical mill. Sure beats using a file. If you take a good look at my car, you can see it has taken the character it has because I am basically a machine shop guy, not a welder. So whenever a problem pops up, I solve it using a bandsaw, lathe, drill press and milling machine. That's why I'd like to see a Duratec installed by someone with a more balanced set of talents. I'm sure it would only vaguely resemble my car.

Bill
 

Bill Blue

Platinum Level Sponsor
The installation is complete. Tried to start the engine. Cranked it until the oil pressure light went out, it never fired. The battery was showing signs of getting weak, so I hooked up the charger and called it day. Later, Barb, who was drafted to be my vigilant safety person, noted the dead engine and wondered if I could check to determine if gasoline even made its way to the carb. Things suddenly clicked. I was using a fuel pressure regulator that I had never used. I had set it on 1 lb. That is very close to zero! So I have set the regulator on "2". Will try to start it tomorrow. In the meantime, here is pic of the installation.

Pretty stock looking. Air filter housing is stock, as are the accelerator and "choke" cables.

Bill
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