engine and drivetrain Weber Dcoe Progression Holes

[downhillwolf]

Hello,

I have a long lasting problems with my dual Weber 40DCOE19 in the range 2000-3000rpm.
Now i have looked at one 2002 with alfa 40DCOE44/45 conversion and i know that problem is in the progression hole arangement and size. I have 55f8 and it's not good since his 50f15 is ok.
Can someone picture his progression hole arangement and what size did he enlarge them.

Best regards

Blaz

[TobyB]

Hmm?

 

Who do you mean by "he?"

 

However, like you, I'd like to see a progression hole drilling that worked well...

 

t

[downhillwolf]

It was meant for my friend with 40DCOE44/45 with 50f15 idle jet.
Since i know that AlpinA used this type DCOE twin carburetors(40DCOE19 and 45DCOE19) so on 40mm and so the 45mm carbs.
I still dont know how did they work it out, was 70's gasoline so much different or did they not use 2000-3000rpm range?
 

[75duce]

The key to locating the progression hole is . It must centered over the throttle plate at Idle so as soon as you crack open the throttle the hole is exposed . The gas we get now is called e10 10% alcohol . Idle jet and idle mixture needs to be richer especially with a bigger cam.

Edited October 3, 2013 by 75duce

[downhillwolf]

The key to locating the progression hole is . It must centered over the throttle plate at Idle so as soon as you crack open the throttle the hole is exposed . The gas we get now is called e10 10% alcohol . Idle jet and idle mixture need to be richer expecially with a biger cam.

Yes i know that we have alcohol inside gasoline, but we still get better gasoline don't we?

Do use have drilled progression holes? Can you attch picture of that?

[75duce]

No the gas we get is  not better. Gas with alcohol needs a richer mixture . No I did not need to drill new progression holes. Shine a light down the carb and look at the holes from above also take a close up pic and post it up . If the plate is not centered over the first hole you need to drill a new one there . You may also not have your idle mixture screws turned out enough. set it real rich just for a test  and see what happens at 2- 3000rpm while driving .

My car with a sport engine needs a 60 f8 idle jet and a rich idle mixture to get good clean performance in the 2-3000 rpm range .

Idle jets should really be called pilot jets because you are on them at 2-3000 rpm cruising along just off idle.

a interesting test is to remove the main jet stacks completely and drive the car carefully and slowly you will be able to see just what the

idle jets are doing and were the main jet starts tipping in because the engine will die.

My car runs weber 3x dcoe 45 #9 and has non removable progression hole covers so i cant show the holes but there are three and they are located just  how they need to be with the throttle plate centered over the first hole at idle.

Edited October 3, 2013 by 75duce

[downhillwolf]

Thanks for that tip, i have in stock also 50f8 and 55f8.
I have a picture of progression holes:
Mine(this is the same carburetor as in my car)...

From my friend...

I don't want to drill progression holes since there is no way back...
The carburetors from my friend was from 2.0L alfa romeo engine made for racing...
 

[TobyB]

That's not a progression hole, that's a leak!

 

The holes you have look familiar.  You can actually tune where they kick in by modifying the

throttle plate- drill small holes in it to get it to close more, or file the edge off it to get the

progressions to be exposed earlier.  Or even bend it, but that seemed like a hack to me.

 

You CAN epoxy up old holes- there was a thread years back about doing it, but I couldn't find it.

 

In your case, if you can come up with some repeatable way to figure out where the throttle plates are when your

engine goes soft, you'll be miles ahead. I had a data logger on the shaft of the race car, so it was

pretty easy- get it to reliably stumble, mark the number, then in the pits with the engine off,

get the data to match.  It found several problems, including a bent throttle shaft.

 

t