Weber dcoe 45 jetting Help

[2002Scoob]

Yep, I bumped the overall curve up across the board for the bottom-end to raise the initial and idle RPM's, and kept the 'all in' of 30 degrees at 3000. Can't remember what I settled on thou... haven't started the car in a while to check, it's just what I could find from my past-posts on the subject :)

[Gre@semonkey02]

Yep, I bumped the overall curve up across the board for the bottom-end to raise the initial and idle RPM's, and kept the 'all in' of 30 degrees at 3000. Can't remember what I settled on thou... haven't started the car in a while to check, it's just what I could find from my past-posts on the subject

Here a picture of mine now

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[2002Scoob]

Wacky... I've never seen one of things. 

 

Does it just interpolate a curve between those points? 

 

And is each knob additive on the one before it? so if you set your initial at 15... and your second dial at 15 as well, you've got a total of 30 at 3k? 

 

And then you 8K is another addition on-top of the previous two? 

 

 

[Gre@semonkey02]

If your idle jet just says 50 you have the wrong type of idle jet installed,  The IDA series carburetors used idle jets that look EXACTLY like the DCOE jets EXCEPT they don't use a air corrector hole, they have the air corrector built into the jet holder and they are numbered.  This would be a big reason you are running rich!!!!
 
I don't know how an xdi system works but if it is like the old Electromotive system they have a setting for initial timing then another knob for the amount of ADDITIONAL advance by 3000rpm and then another knob for ADDITIONAL advance by 8000 rpm.  So if you have an initial advance of 16 degrees and then you are ADDING 21-24 deg by 3000 that is 35-40 degrees total advance with a 10:1 compression ratio you could be having some detonation issues.  The -2 degrees by 8000rpm is insignificant. 
 
Have you confirmed that the numbers you have set on the dials are actual advance at the crankshaft with a timing light? 

This is the idle jet I have now it says 50 but it has a hole on the side

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[Gre@semonkey02]

Wacky... I've never seen one of things. 
 
Does it just interpolate a curve between those points? 
 
And is each knob additive on the one before it? so if you set your initial at 15... and your second dial at 15 as well, you've got a total of 30 at 3k? 
 
And then you 8K is another addition on-top of the previous two? 
 
 

Yes I'm running xdi electronic ignition no dizzy

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[Preyupy]

The “hole on the side” is the air bleed and it is referred to by an “f#” a very small change in the size of that hole makes a large change in mixture. We can’t tell you what size it is just looking at that picture.  A lot of people have given you advice about how to get to a reasonable starting point.

 

 YOU HAVE TO BE ABLE TO KNOW EXACTLY WHAT YOU HAVE AND BE ABLE TO CONFIRM IGNITION TIMING BEFORE ANYTHING ELSE CAN BE DONE. 

 

Some of us have been doing this a long time and we know there are no short cuts. My personal Weber carb “kit” has 36 of every main,aircorrector, idle, pump, inlet valve jet and over 200 e-tubes (when you start tuning V12’s and every jet change s at least a dozen jets)   When I’m tuning I make a change and then keep changing until it is correct.  If you have to stop every time and order 1 set of jets and wait 3-5 days to try again your car might be running well sometime in 2020. If you don’t want to go through the time and expense of becoming a Weber expert you might consider paying someone that knows what they are doing to set them up for you.  Believe me it will be less expensive than the inventory of parts you will be buying. Once they are jetted correctly you should not have to change them unless you change the engine or change elevation by 3000’ or more. 

Edited April 23, 2019 by Preyupy

[Gre@semonkey02]

The “hole on the side” is the air bleed and it is referred to by an “f#” a very small change in the size of that hole makes a large change in mixture. We can’t tell you what size it is just looking at that picture.  A lot of people have given you advice about how to get to a reasonable starting point.
 
 YOU HAVE TO BE ABLE TO KNOW EXACTLY WHAT YOU HAVE AND BE ABLE TO CONFIRM IGNITION TIMING BEFORE ANYTHING ELSE CAN BE DONE. 
 
Some of us have been doing this a long time and we know there are no short cuts. My personal Weber carb “kit” has 36 of every main,aircorrector, idle, pump, inlet valve jet and over 200 e-tubes (when you start tuning V12’s and every jet change s at least a dozen jets)   When I’m tuning I make a change and then keep changing until it is correct.  If you have to stop every time and order 1 set of jets and wait 3-5 days to try again your car might be running well sometime in 2020. If you don’t want to go through the time and expense of becomes no a Weber expert you might consider paying someone that knows what they are doing to set them up for you.  Believe me it will be less expensive than the inventory of parts you will be buying. Nice they are jetted correctly you should not have to change them unless you change the engine or change elevation by 3000’ or more. 

Okay thanks

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[Hans]

As per Preyupy, I spent hours fiddling with my carbs only to discover a bad plug wire, and more importantly, I wasn't using enough advance. Getting that right made a huge difference. Hence our ongoing return to this step. You need a timing light to confirm what is happening. Swapping jets is down the list.

[Gre@semonkey02]

As per Preyupy, I spent hours fiddling with my carbs only to discover a bad plug wire, and more importantly, I wasn't using enough advance. Getting that right made a huge difference. Hence our ongoing return to this step. You need a timing light to confirm what is happening. Swapping jets is down the list.

Ya I'll double check my timing Gota mark the flywheel and see where is it

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[Gre@semonkey02]

You need to remove the #1 spark plug and take the valve cover off.  Turn the engine over until the timing mark on the cam is directly under the oil spray bar. Now with a long skinny rod or screw driver reach through the spark plug hole and feel the top of the piston.  With the car in top gear gently rock the car forward until you feel the piston start to move down, now do the same going backwards.  It takes a bit of trial and error but you want to find the exact point of TDC, you can move it forward until you feel the piston just start to move and put a mark on the flywheel just inside the window then do the same when you are going backwards then split the difference between the 2 marks to give you a true TDC.  Now mark the flywheel! 
 
The sensor you have on the front of the engine is supposed to be at 11 teeth after the missing tooth when the engine is at TDC.  Every tooth is 6 degrees so if you are off by just a half of a tooth you will be 3 degrees off. 
 
You have to know where you actually are with timing and you MUST confirm this with a known ACCURATE TDC mark on the crankshaft pulley or flywheel and check it with a timing light.  Then you can adjust the initial timing dial to get what you really want.  Right now you have the dial set at 16 degrees but you have no idea if this is what is actually happening.  You might find that the "initial timing" knob is off by 10 degrees or more (that is less than 2 teeth on the wheel) don't worry about it, just set the initial timing at some known setting and WRITE IT DOWN.  This is your new starting point.   Once you have a known initial timing you can safely work on a TOTAL advance number (again I would probably start at 32 deg BTDC at 3000)  run the 8000 rpm knob at 0 for now. 

I have a timing light with advance feature
What do I set my timing on my front pulley how much advance do I put on my light I can't really find anything on the forums everything is for the flywheel ball that I don't have.

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[Simeon]

5 hours ago, Gre@semonkey02 said:

I have a timing light with advance feature
What do I set my timing on my front pulley how much advance do I put on my light I can't really find anything on the forums everything is for the flywheel ball that I don't have.

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Ignore the posts about the ball. You are trying to verify the timing set by your XDI. 

 

Mark an accurate TDC and then set your light to 15 degrees BTDC. Flash the pulley  at idle and you should get the timing mark as your ignition should be advanced at 15 degrees BTDC at idle (your initial). You should then be able to set the engine speed to 3,000 rpm and the light to whatever you have the 3,000 rpm advance set to. 

[Gre@semonkey02]

 
Ignore the posts about the ball. You are trying to verify the timing set by your XDI. 
 
Mark an accurate TDC and then set your light to 15 degrees BTDC. Flash the pulley  at idle and you should get the timing mark as your ignition should be advanced at 15 degrees BTDC at idle (your initial). You should then be able to set the engine speed to 3,000 rpm and the light to whatever you have the 3,000 rpm advance set to. 

Okay perfect thanks

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[Hans]

are you sure the flywheel doesn't have a TDC mark?  Or did it not have a positioning dowel? Much easier to see teh front pulley; challenge is getting a pointer attached.

[Gre@semonkey02]

are you sure the flywheel doesn't have a TDC mark?  Or did it not have a positioning dowel? Much easier to see teh front pulley; challenge is getting a pointer attached.

I have aftermarket flywheel that's my problem I can see the market on the front so I'll go with that there's a pionter on my from cover I have late engine in my car from 84

 

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[Gre@semonkey02]

Well I put the 45f9 idles good same thing as my 50 I had in then had to turn the idle mixture out 3 turns I went for ride anything before 3000 rpm it stumble and after that lots of power wakes right up I set my floats to 12.5 at the bottom is this right ?

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