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Sun Oct 26, 2014 2:58 pm

I have recently finalized a 1.7 Type IV rebuild for my 72 Bay but I am having trouble getting it tuned just right.

I am using dual Weber 44 IDF carbs.
- I have triple checked my valve clearances.
- I have made sure the distributor is in the proper position for initial start up and tuning. (The thing fires right up and idles but has some hiccups)
- I have also checked to ensure I have the wires in the proper firing sequence
- I have adjusted the idler screws as low as possible without the engine dying.

I bought a snail style synchronizing tool from the Weber website and the tool broke... go figure. Almost shot a small metal counterweight into my carb.

I am about at my wits end with this thing but I know I am so close to having a function ride.

If you can provide some advice on what else i need to check, i would appreciate it. Also, if anyone has a contact around the Northwest Suburbs of Chicago that would willing to help, I'd love to hear from them.

Thank you in advance.

Sun Oct 26, 2014 3:22 pm

I had the same prob.the idler jets 2 on each carb are what is aparently the prob there is a kit for 80 bucks with diff size jets to change them out. that was my prob anyway. Ifound out that they(weber) reccomend the idler screws be bottomed out and back them out to as close to 1 as possible. I went through many different opinions on how far to back them out but ending up at 1 1/2 worked for me. good luck

Sun Oct 26, 2014 8:24 pm

What is the history of your Weber 44 IDF carbs, New, Used?

By your description it’s hard to figure out what your problem is “tuned just right”…

To tune them you do need a working snail style synchronizing, unless you are a carb tuning God ;0)

I had trouble getting my 44 IDF’s running perfectly until I adjusted the Air Bypasses, they are set at the factory, however with a snail style synchronizing I was able to adjust my engine so it purred evenly without missing a beat for as long as it idled and had throttle response as sharp and crisp as a café racer… the perfect idle had eluded me until I adjusted the Air Bypasses. However somewhere I have the original factory settings for the Air Bypass screws if I need them; I once asked a redlineweber rep what I should do with a used set of 40 IDFs I bought in regards to the Air Bypass screws, he said to screw them all in, and adjust the carbs…

http://www.redlineweber.com/html/Tech/idf_adjustment_controls.htm

However just as an FYI, if you are trying to tune your carbs as per Best Lean Idle without an A/F ratio meter on each cylinder it would not be hard to have all your cylinders running at different A/F ratios…

I managed to get mine purring without an without an A/F ratio meter, but every part and aspect of my engine was balanced and blue printed, which probably made it easier to tune ;0)

Sun Oct 26, 2014 10:55 pm

did you or did you not synchronize them at idle and 1500 RPM - yes or no.

Mon Oct 27, 2014 3:52 am

44s are to big for 1.7 liter.

Mon Oct 27, 2014 6:07 am

How can u say they are too big :shock: ,you don't know, he could have some huge ass hogged out heads and a 500+ lift cam :lol:
what vents? and jets u running,got 3 1/2 lbs of fuel pressure? floats set proper?

Mon Oct 27, 2014 6:10 pm

Alright, I'll start from the top.

The carbs are used and most likely in need of a rebuild. They were on the bus when I acquired the vehicle and have since been swapped around on a couple of motors but always ran fine.

I am far from a carb god and honestly I am scared to death of trying to rebuilt them myself.

When I was syncing the carbs, I only set them at idle. I was not aware of the 1500 RPM point. That would be done through the linkage, correct?

I also though the carbs were too big for the engine but have ran them successfully in the past.

On a side note, I have a secondary carb set up for a "backup" engine that is a Holley progressive. I have never had much success with this but would be willing to swap the carb set up if it is considered more desirable for the 1.7.

Thanks again guys

Mon Oct 27, 2014 7:17 pm

Jacksone Howe wrote: Alright, I'll start from the top.

The carbs are used and most likely in need of a rebuild. They were on the bus when I acquired the vehicle and have since been swapped around on a couple of motors but always ran fine.

I am far from a carb god and honestly I am scared to death of trying to rebuilt them myself.

When I was syncing the carbs, I only set them at idle. I was not aware of the 1500 RPM point. That would be done through the linkage, correct?

I also though the carbs were too big for the engine but have ran them successfully in the past.

On a side note, I have a secondary carb set up for a "backup" engine that is a Holley progressive. I have never had much success with this but would be willing to swap the carb set up if it is considered more desirable for the 1.7.

Thanks again guys

You want to sync them basically at idle and 1200 - 1600 RPM. What you are trying to do is make sure that the linkage is working right so you don't end up lopsided with how the carbs are working. It usually takes three or four tries because you are also going to check the mixture screw at idle when and that will affect the RPM as well. Once they are synced at idle compare them at say 1500. Hopefully they will be dead on. If not look at the linkage and everything and try to figure what you need to do to bring them into sync. Each linkage is different. I used to set them as close as I could with the balance tube disconnected and plugged. Then when done the balance tube is reconnected and the engine will purr.

Mon Oct 27, 2014 8:38 pm

madmike wrote: How can u say they are too big :shock: ,you don't know, he could have some huge ass hogged out heads and a 500+ lift cam :lol:
what vents? and jets u running,got 3 1/2 lbs of fuel pressure? floats set proper?

Highly unlikely.

Synching them at that high of an idle speed will mean your into the progression circuit.

Mon Oct 27, 2014 8:55 pm

udidwht wrote: madmike wrote: How can u say they are too big :shock: ,you don't know, he could have some huge ass hogged out heads and a 500+ lift cam :lol:
what vents? and jets u running,got 3 1/2 lbs of fuel pressure? floats set proper?

Highly unlikely.

Synching them at that high of an idle speed will mean your into the progression circuit.

I don't know if you were referencing my post to check them both at idle and 1500 RPM or not. You want to always sync them at idle first, and then double check them about 1500 RPM or so. If they aren't still synced then you have to look for the cause and fix it. At near wide open to wide open throttle they will always be in sync and draw equally, and at idle most people check them as to draw and mixture. HOWEVER just off idle at low RPMS they have to be the same too as to draw. That is a function of the linkage. If that is messed up in any way the bus will never perform smoothly going from Idle to driving. The complaint will be it runs fine on the freeway, idles fine but is doggy off the line.

Mon Oct 27, 2014 9:44 pm

SG is correct for syncing multiple carbs and i learned long ago to leave the
heim links (Lock Nuts) Loose when synchronizing But, without knowing anymore than.......
"I just finished building a 1.7 engine" as the OP said then, 44's are a little large.

I run 40 IDF's on a 2.0 big valved high lift cam and higher than stock comp.

So, the OP should post the 44 idf specs that are installed in those 44's :?:

Tue Oct 28, 2014 6:44 pm

I do not know the exact specs of the carbs. They were on the bus when I acquired it.

I will try syncing at idle and higher RPM to get the linkage set better. If that doesn't work I'll start digging around for more details on a carb rebuild, jetting etc. The bus idles so well that I am keeping the faith that it is only a few small tweaks.

Thanks again guys

Tue Oct 28, 2014 9:10 pm

Jacksone,

Pull the carbs and check All the jettings on the 44's

Here is a comparison for 40 IDF
AND 44 IDF Basic Jetting

28 MM Venturi's
Air correction 2.00
Emulsion Tubes F-11
Pump Jets 50
Idle Jets 55
Main Jets 130

44 IDF Carbs usually start with Larger 32 mm Venturi's
and Main AND Idle Jets Main jets 155 and Idle Jets of 60

This can be your starting point for determining what you will need to change
for jetting based on your engine.

Changing Venturi's from 32 to 28 along with Main jets will be a start IF you
know the parts installed on your Carbs.

I hope this will help you.

Wed Oct 29, 2014 9:43 am

Dual carbs are a bitch. Guys think they can just buy a new set of Webers and bolt and go. It's far from that.

Fri Oct 31, 2014 8:12 pm

old DKP driver wrote: Jacksone,

Pull the carbs and check All the jettings on the 44's

Here is a comparison for 40 IDF
AND 44 IDF Basic Jetting

28 MM Venturi's
Air correction 2.00
Emulsion Tubes F-11
Pump Jets 50
Idle Jets 55
Main Jets 130

44 IDF Carbs usually start with Larger 32 mm Venturi's
and Main AND Idle Jets Main jets 155 and Idle Jets of 60

This can be your starting point for determining what you will need to change
for jetting based on your engine.

Changing Venturi's from 32 to 28 along with Main jets will be a start IF you
know the parts installed on your Carbs.

I hope this will help you.

40's come stock with 50 idles and 115 mains

44's come stock with 55 idles and I believe 130 or 135 main.

Fri Oct 31, 2014 10:34 pm

Read the specs in the Weber Manual UDIDWHT. :?
I am not in the debating mood for something that is already known and really
has no bearing on this question from the O.P.

He really needs to post his findings and post them here and then if you like WE
will debate this. I have been doing this since 1967 and really don't care what you think about my input here. :oops

Fri Oct 31, 2014 11:17 pm

old DKP driver wrote: Read the specs in the Weber Manual UDIDWHT. :?
I am not in the debating mood for something that is already known and really
has no bearing on this question from the O.P.

He really needs to post his findings and post them here and then if you like WE
will debate this. I have been doing this since 1967 and really don't care what you think about my input here. :oops

1967 is that all? Your young. Just to add. The following is my engine after haven synched the carbs by ear & eye only :wink: 67...that all? Whew...seems like yesterday.

https://www.youtube.com/watch?v=DqScv6lBIDI&feature=youtu.be

Sat Nov 01, 2014 9:51 am

Try following this guide:

http://www.aircooled.net/synchronize-dual-vw-carburetors-103/

There may be a few other articles there to help you through the process.