Weber IDA 48 info. needed

[priobe]

I would like to find out if most of you set your fuel pressure when the engine is warm or when it is cold. Fuel pressure fades after motor gets warm

Also,

I have made some changes to my setup and would like to know your thoughts.

My current setup:
37 choke
air holder 120
idle jet 65

main air 210
emulsion tube F16
main jet 165
bypass 55

Timing - 17 degrees
MSD - 1 silver (light) & 1 blue spring -- bushing - blue (21 degrees)

Fuel pressure regulator (Holey Light pressure) 3.0 psi cold
No return line

Engine runs 85 % Good, has a stumble between 2200 - 2800 RPM

Spark plugs gapped @ 40 thou.

When you pull the spark plugs they still rich (black carbon dry).


Here are some of my other findings:

choke 40 ( much better engine response)
60 idle air holder (120 too lean popping though the carb)
60 jet
F16 emulsion tube

I am tempted to try an drilling out the idle jet holder to 80 or 100 but many people do not suggest this?

Any thoughts

Btw- spark plugs are still rich

[ENTDOC]

my present set up is-- 120 holder, 70 idle jet,F16 e tube, 180 main jet,205 ac, 40mm chokes. great performance but still a slight stumble at 2500 or so, plugs have not fouled since I went with 40 chokes. I would like to find some f14 tubes

[priobe]

ENTDOC,

Are your plugs burning correctly or they on the rich side?

[ENTDOC]

definitly better than with the 37 chokes. I plan to hook up the LM1 soon to get a better idea of things

[priobe]

My question to you is, if you are experiencing stumble in the 2000 + range, could you reduce the air holder to 100 to achieve the same as increasing the fuel jet ?

I am experiencing the same stumble at this range but when I change the air holder to 60 the stumble disappears. But it runs too rich.

I am trying to get a understanding of how these Webers work.

[ENTDOC]

changing to 100 holders would probably work. Read Eljaro's thread on unusual jetting here on CC, he seems to have it worked out.

[priobe]

ENTDOC,

I have read that thread and it is very interesting. I t actually makes alot of sense to me but no sure why not too many people support it.

In his thread he even speak about his plugs burning properly when others say that it is normal to have your plugs foul. That it is a normal characteristic of these carbs.

Many other do not agree with drilling out the holders but they nolonger make any values except for 120.

Is everyone tuning around the 120 holders?

[ENTDOC]

I was told by most that only 37 mm chokes should be used or you woud have drivability problems around town. I have not found that at all and I think that is why most have trouble with fouling. 37's are for small blocks. My car runs beter now than it ever did with the Holley set up but I can tune it even better, that is the advantage of the webers. I find it fun so it is no big deal. An LM1 is a must to get it correct just as with any system. I may send mine off to have the third progression hole drilled, this seems to help also.

[Brent Mills]

I had been running the 37 chokes, but it ran like crap (rich) and had a pretty severe stumble. I'm now running 42's and it's really close. I think the 37 chokes caused too much vaccume and pulled in too much fuel.

[priobe]

Hmm,

I am glad to see more people running larger than 37 chokes. I will need to check my notes and try my 40 mm chokes again.


Also, this has been bothering me for a while now. When I purchased my Webers (used) I noticed the Aux. Venturi was cut even with the top body of the carb. DOes anyone know why this was done? Also, should I purchase New (longer) Aux. Venturi's?

[Rick Parker]

The short Aux venturis are used when the shorter stacks are used. Such as in a Daytona Coupe application.