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1602 - DCOE 40 or 45?


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Big vote for 40's, here-

otherwise, your throttle response will be a switch.

Also, you stand a better chance of getting a transition drilling pattern

that gets fuel in early enough.

That's based on general DCOE behavior...

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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I'm not a fan of high performance cams on street cars. I had a 292 on one of my cars, and I didn't care for it for a street car. The idle is too lumpy on anything beyond the stock cam profile. There is a reason why the factory used the same profile cam on all their varieants including the Ti and Tii.

I would go with the 40s. And note the small choke or venturi size (27mm) on the recommended settings for the 1600 Alpina. The only other car that I know of which came with that venturi size on DCOE 40s is the Alfa Giulia 1600 Super. You'll have to look around for those venturis since a lot of Weber distributors don't stock them. hHey make a big difference in driveability. Remember the 1600 has a very short stroke, and you want to size the venturis down to get more velocity into those combustion chambers and increase driveability and response at lower rpm's.

SLavs

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sorry, but if you had a "lumpy idle" with a 292, it wasn't the cam. you had other issues. 292 is pretty mild. i had them in two different m10 engines. both with sidedrafts. 40 and 45's. idle was butter smooth at 900rpm in all cases.

for op...what CD said. buy a few books on webers and read before choosing. you will find that 40 or 45 is not a decision. it is a result of process involving displacement, intended use, cams, desired location of power band, etc. that process leads to what main venturi to use. then you get the carb bodies (40 or 45) that best fit the needed venturi.

neither a 40 or 45 is "better" or "will result in a throttle switch". they are just different sizes of "parts holders".

2xM3

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40 mm dcoe's with 34mm choke's is going to work the best for all around

use . Dont get a new set unless you get a forth progression hole drilled in

them first . What you want is a old set of Italian dcoe 40 #2.

jan2011053.jpg

Here is a pic of my 75 3 dcoe 45 #9's

75 2002 M20 alpina rally clone

77 323 gt3 race car

91 e34 M5

86 Ford F-250 521 big block 

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Hey, if you need manifolds, turns out a set I've got that I thought were for a 2L head

are actually for the 1600.

RacerY at comcast dot net

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Between the smaller 1600cc displacement and stock compression that I'm assuming you have, a 292 cam is probably the most radical you would want to go with and I would say the 40DCOE's would be more then enough.

Have you considered a 38/38 Weber 2 barrel? It probably would be better for the street as far as low end punch. Also easier for you to get set up properly if you don't want to put the time into the dual set up. DCOE's definitely have a steeper learning curve.

How much do you like to read and tinker?

Mike Katsoris CCA#13294                                                

74 InkaGangster 4281862

2016 Porsche Boxster Spyder,    2004 BMW R1150RT,  
76 Estorilblau 2740318                      

 
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40 mm dcoe's with 34mm choke's is going to work the best for all around

use . Dont get a new set unless you get a forth progression hole drilled in

them first . What you want is a old set of Italian dcoe 40 #2.

jan2011053.jpg

Here is a pic of my 75 3 dcoe 45 #9's

Do you have any detail on the location and size of the 4th progression hole?

No amount of skill or education will ever replace dumb luck
1971 2002 (much modified rocket),  1987 635CSI (beauty),  

2000 323i,  1996 Silverado Pickup (very useful)

Too many cars.

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Great Info so far, i appreciate the insights!

I am going with the Ti pistons, so 9.5:1 compression, that is what prompted my thought of a 304 cam, a 900 rpm idle doesn't bother me.

I'm an engineer by profession so tinkering isn't an issue, that's half of why i bought the car. Drive it all summer and have it in the garage for the next upgrade all winter.

I'll get a weber book and check out the technical details on the carbs, i'm assuming there is some type of nomograph showing the appropriate sizes based on displacement and desired power band range? I do want to stick with the side drafts as I have the boots and air box for the 1600 ti and wanted to use those.

On other question - any value in up-sized valves? I've heard that its only useful on a race engine, any experience with that setup in a street engine?

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