Weber 40 IDF help, My usual guy had back surgery and can't help now Options

[mmichalik]

@porschetub
@superhawk996

I pulled the idle jets of one of the carburetors and they were both 65

The emulsion tubes were F11 and 130's

Venturi's are 32

[Superhawk996]

Venturi's are 32

Yeah that’s gonna’ suck (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/lol-2.gif)

Seriously though 28 is going to be better for street drivability and throttle response. 30 is middle of the road, and 32 is way better suited to top end power / high rpm track type use. Personally back when I ran IDF’s I preferred the 28’s. Driveability is a big deal and more pleasant to drive even if that means giving up a little top end HP at redline. Keep in mind the amount of time you really spend at 5000 - 5500 rpm is minuscule.

nditiz1’s recommendation is a very sound stating point.

With the setup you have - not at all surprising you’re not a happy camper.

Here is the standard venturi selection chart that has been around for a long time that came out of one of the aftermarket Weber tuning books or something like that (ie not my data). Keep in mind this chart is for Horsepower - not optimum drivability.

[mmichalik]

Just an FYI, my goal is to have a solid driver that has some balls to it when I want hot rod around.
I'm thinking about moving the main jets to 120, the venturis to 28 or 30 and the idle jets to 55
and then time and tune from there.

Thoughts?

[Superhawk996]

Pick your Venturi 1st

Then general rule of thumb is main = 4x Venturi to maybe 5x Venturi

In my opinion better to have a strong vacuum signal on the idles - you will do far more driving on the idle circuit than you think. Strong vacuum is what yields good throttle response.

If you have the money to play - buy both 28 and 30s then see what you prefer. Sell what you don’t use when you’re done.

[930cabman]

Just an FYI, my goal is to have a solid driver that has some balls to it when I want hot rod around.
I'm thinking about moving the main jets to 120, the venturis to 28 or 30 and the idle jets to 55
and then time and tune from there.

Thoughts?

Mr Hawk has it correct with the venturi size. I am a carb guy and am running a similar motor and she did not like 32 vents, but runs great with 28's. I am not sure of the mains, idles, airs, .... but like Phil says, start with the vent's and go from there. Do you have any of the Weber tuning manuals?

[mmichalik]

Just an FYI, my goal is to have a solid driver that has some balls to it when I want hot rod around.
I'm thinking about moving the main jets to 120, the venturis to 28 or 30 and the idle jets to 55
and then time and tune from there.

Thoughts?

Mr Hawk has it correct with the venturi size. I am a carb guy and am running a similar motor and she did not like 32 vents, but runs great with 28's. I am not sure of the mains, idles, airs, .... but like Phil says, start with the vent's and go from there. Do you have any of the Weber tuning manuals?

I ordered a Weber tuning manual over the weekend. Should be here soon.
I also ordered 28's and 30's for the Venturi's as well as 120 and 125 main jets.

[VaccaRabite]

Just an FYI, my goal is to have a solid driver that has some balls to it when I want hot rod around.
I'm thinking about moving the main jets to 120, the venturis to 28 or 30 and the idle jets to 55
and then time and tune from there.

Thoughts?

One data point does not make a line. That said, my 2056 was happy with a .55 idle. I bet your 2L would prefer the .50.

You will definitely want the 28vent.

Change one thing at a time. Don't make a bunch of changes art once. You want to be able to see what works and what does not. Change 2 things, and you won't be able to tell what helps and what hurts.

Zach

[mmichalik]

OK, I'm going in today. (IMG:style_emoticons/default/smile.gif) Changing the venturis to 28.
Hopefully I will have some good news by the end of the day
Thanks for all the advice gentlemen!

[mmichalik]

Just finished changing the venturi's, they were 34's not 32's..... I put 28's in. It started up and maintained idle, I have not driven it yet though. Waiting for a buddy to drop by and drive a chase car just in case.
Started easier than usual and Idle exhaust smells better too. Still fat but better.....

[mmichalik]

Drove it. Venturi's made a huge difference, no more flat spots and a lot more torque.
Didn't like the smaller jets though. We got it to run good on 60's for the ilde jets, which is better thant the 65's that were in there but not as good as the 55's or 50's that I wanted to try and use.
Have not played with the mains yet but, those should be easy.
Going to be driving it over the next week or so, to watch all the adjustments that were made but I'm happy with where we ended up today for sure

[930cabman]

Drove it. Venturi's made a huge difference, no more flat spots and a lot more torque.
Didn't like the smaller jets though. We got it to run good on 60's for the ilde jets, which is better thant the 65's that were in there but not as good as the 55's or 50's that I wanted to try and use.
Have not played with the mains yet but, those should be easy.
Going to be driving it over the next week or so, to watch all the adjustments that were made but I'm happy with where we ended up today for sure

(IMG:style_emoticons/default/piratenanner.gif)

I tried the same a few years ago with a 2056 build, changed to 28 vents and 3 years later all is good. As I recall the jets sizes follow proportionally with the vent sizes. the idle mixture screws should be 1 1/2 turns out from being seated, this dictates the idle jet size.

[porschetub]

Just finished changing the venturi's, they were 34's not 32's..... I put 28's in. It started up and maintained idle, I have not driven it yet though. Waiting for a buddy to drop by and drive a chase car just in case.
Started easier than usual and Idle exhaust smells better too. Still fat but better.....

Wow those are big vents !!! ,with minor jetting changes results will be great ,must have run like a pig on those vents and idles ...really reduced vacuum signal and poor transition for that reason, reckon this combo will really come alive well tuned, every motor is different and not same for same there are too many variables to consider , you are getting close ,cheers.

[Eric_Shea]

Put 28's in it.

We have a jetting spreadsheet. You're at 1,300' as well. Nothing huge but it may play into jetting and AC jetting. Cam also plays into this.

28's are the best advice I've seen here. It will probably make the biggest change, getting you close to or spot on what you are looking for.

(ooooooooooops... just read the last few posts! LOL)

[930cabman]

Invest in Pat Bradens book, Weber Carburators

[mmichalik]

@Eric_Shea Agreed, they made a HUGE difference to the point that the car runs at a whole new level. Thank you for your comments here and again, thank you EVERYONE for the advice given.

@930cabman Just purchased it as well.

Was out this week, traveling on business but, I'm going to get some miles on it this weekend.

[930cabman]

@Eric_Shea Agreed, they made a HUGE difference to the point that the car runs at a whole new level. Thank you for your comments here and again, thank you EVERYONE for the advice given.

@930cabman Just purchased it as well.

Was out this week, traveling on business but, I'm going to get some miles on it this weekend.

Glad to be of assistance, there are several other Weber books out there. maybe a good thing your regular carb guy was not able to get your carbs tuned