Single Carb Conversion 2 Barrel Progressive Holley,Weber 740 carb

[westgl]

Here is a exploded view of the Motorcraft, Holley, Weber 740 Carb.

https://www.carburetorfactory.com/expvw09.html

Weber 740 Holley Motorcraft

• westgl
• Nov 30, 2013

 

[Omega Man]

Thinking of making the switch?

~O~

 

[westgl]

I removed the auto choke on my 740 Carb. as the carb. is too big to fit between the frame for me comfortably with the auto choke on it.

There is a vacuum port under the auto choke, that needs to be covered/Plugged.

I made a small block off plate, a manual choke could be made, very easily.

I got rid of the oem inlet can fuel filter going into the carb. & put a 1/8" pipe thread 90degree brass fuel inlet fitting.

I took off the front solenoid, and put in a plug, and another plug in under the fuel inlet is a smog inlet another plug here.

I removed the oem Choke lever arm on throttle shaft.

I bought a uni-Link Kit.

The Uni-Link is what i used to set up my throttle cable, it Holds the stock Pull cable end, and does a pretty good reliable job, I am getting full throttle, at this point and still have more movement at my hand to go than the Carb. needs to go to full throttle at the carb.

From what I have read, & when I pulled that vac. unit apart, it looks like there is some adjustment in that advance unit, to advance the timing some.

I need to make a bracket for the cable Adjustment Hold.

I have a design sketched out, for the stock Cable adjustment Hold.

The stock cable may be too long, If that is the case I have another cable that is 4" shorter, it looks just like the 83' GL1100 cable only 4" shorter, i think it was for a CB750 but i will have to verify that I have what bike it was for on the cable.

Only problem is finding stuff in my new shop is tuff, a lot of stuff still in boxes after the move, but the new shop is HUGH!!!

My bike is a 83' GL1100 and has a Vacuum operated advance.

I am using the vacuum port on the right Rear oem intake manifold, (The Sync Port) and a fitting that I used for syncing my carbs screw into that manifold, I may have to solder the end closed and drill the hole with a small drill bit to reduce the vacuum for advancing, this may take a few times to get it just right, But it is easy and accessible.

I am Contemplating adding heat to the manifold center section.

 

[westgl]

Yes Omega Man,

I have a Carb rack for my GL1100 that I went through and works great, (Randaak kit two years ago) perfect no stumbling or flat spots at all.

But!! I have had at least 4 Hydro lock situations, that were all my fault, for not turning off the dang fuel cutoff valve, My GL1200 Never does that EVER!

I am also Very interest in the ease of maintenance or lack there of.

I am also interested in, more Engine Torque, in the Low to mid rev range.

I have a 84' GL1200 that may also be a candidate for a single If I can get the GL1100 to run and run well with a single cab. first.

My 84' GL1200 will become a project, Reverse trike over the winter, the added torque will be welcome for a trike.

 

[westgl]

One thing i did first, on the OEM intake Manifolds, was to liberally coat the the Rubber sections with ATF to clean and soften the rubber, i left it on for about an hour, then wiped of the ATF, the rubber looked like new, and felt slightly softer, I want a good seal with No Leaks.

Here Is a picture, Not done yet but coming along.

This is very similar to Joe's Single Carb he did to Hooch.

Joe, gets all the Credit here. Thanks Joe

 

[westgl]

I have been thinking of doing a single carb conversion since two years ago, But the move to a New House set me back.

Seeing Joe do his, made me want to get started even though my shop is not set up correctly yet.
Note i have not tried any of these as this is my first Single carb. Conversion

I currently have 5 carbs. in my shop ready for a single carb conversion.

I have enough to play with, to get a single carb working.

They are,

1. Weber 32/32, DFT Progressive New carb. $90.00 ea good price point Availability is good.
2. Weber 24/25, 740 Progressive Newly Rebuilt. I paid $125.00+ shipping, availability is OK, but could be better. I have seen these listed for $80.00+ shipping that need a rebuild, to over $300. + shipping that have been rebuilt.
The two carbs above look Identical in every way, except venturi size.

3. Weber 38DGAS 38/38 Progressive this was going to be for a Single carb conversion for a GL1500 (stock OEM CV Carbs are two 33mm venturi carbs) The 38DGAS may be Over carb'ed, So maybe the 32 DFT may be the right choice for the GL1500 Single carb. Conversion

Below i have two of each carb as they were going to be a dual carb setup. But they could be good single carb too
4. Solex 34Pict3 single barrel Dual carb setup
5. Solex 30Pict1 Round bowl Single barrel Dual carb setup

 

[westgl]

Weber Carb Adjustment page Link
https://www.carburetion.com/Weber/adjust.htm

 

[Omega Man]

WOW! That is a beautiful clean looking set up. It looks like it could be stock. :good:

~O~

p.s. Yeah Joe is awesome we are so lucky to have him as member/Guru.

 

[mcgovern61]

Wow! That Motorcraft 740 reminds me of the carbs that were on my old '69 Ford LTD wagon with the 390 engine.

Looking at your setup, what manifold is that?

 

[joedrum]

cool read ill use that ....it is true the front barrel is everything hooch is very close here ...is the mix blocked on your 740 mine was

 

[mcgovern61]

joedrum » Thu Sep 05, 2013 11:03 am[/url]":1hpc3gp0]
cool read ill use that ....it is true the front barrel is everything hooch is very close here ...is the mix blocked on your 740 mine was

Out of curiosity, do you need a two barrel carb if the front barrel alone is handling the bike well?

I had a boat with a Chrysler slant 6 engine (225 ci) and a Dodge Dart with the same engine and both had a single barrel carb. Those engine were more than enough power for my tastes!! So.....my question is, can a single barrel carb work on our engines in this arrangement?

 

[westgl]

The Mix?

What do you Mean Joe?

That Manifold is a VW type IV Manifold.

To use the 740 or the 32DFT carb's. I had to open the mounting holes some, lengthwise with my Dremel tool, so that the carb would fit on to the VW Plenum.

When you remove the auto choke there is a small vacuum hole on the carb that needs to be plugged, I made a small plate, to cover it, i was thinking of a small bell crank mounted to that block off plate to actuate the choke manually.

My concern is Ice or icing, and the need for Heat under that Plenum.

Joe are you having any problems with Icing?

Maybe to warm for that now. maybe be 70 degree, or cooler, may cause a problem? That can be added later. I have an idea for that too, just in case it happens.

 

[dan filipi]

mcgovern61 » Thu Sep 05, 2013 9:14 am[/url]":2e1nmbvs]

joedrum » Thu Sep 05, 2013 11:03 am[/url]":2e1nmbvs]
cool read ill use that ....it is true the front barrel is everything hooch is very close here ...is the mix blocked on your 740 mine was

Out of curiosity, do you need a two barrel carb if the front barrel alone is handling the bike well?

I had a boat with a Chrysler slant 6 engine (225 ci) and a Dodge Dart with the same engine and both had a single barrel carb. Those engine were more than enough power for my tastes!! So.....my question is, can a single barrel carb work on our engines in this arrangement?

I was thinking a 1 bbl would be simpler and smaller but my understanding from talking with Joe is the second barrel is needed because the progression (acceleration) is slower coming on which is what we need for the throttle twist.
Makes sense unless I mis understood.

 

[westgl]

I think a single carb. can work

You see a few post up I have two carbs that can work.

LDwingnut has a Single Solex 30PICT1 Round Bowl Carb. he uses a .050 main jet in his setup.

There are videos of this setup running, he claims 0-90 FASST!! No personal experience though.

There is also the Juan fernandez single carb conversion he runs a 34Pict3 there are two guys that show video of them riding there bikes

I will try to post a link to their bike running.

Notice how much faster the speedo is going than the tach.
Must be more torque that stock

LDwingnut carb
Link
https://www.youtube.com/watch?v=abz1Nt8HXrc

Riding

https://www.youtube.com/watch?v=85Et3ot9irY

Juan Fernandez

https://www.youtube.com/watch?feature=p ... WTAp0rsgLg

mcgovern61 » Thu Sep 05, 2013 8:14 am[/url]":28kes6pn]

joedrum » Thu Sep 05, 2013 11:03 am[/url]":28kes6pn]
cool read ill use that ....it is true the front barrel is everything hooch is very close here ...is the mix blocked on your 740 mine was

Out of curiosity, do you need a two barrel carb if the front barrel alone is handling the bike well?

I had a boat with a Chrysler slant 6 engine (225 ci) and a Dodge Dart with the same engine and both had a single barrel carb. Those engine were more than enough power for my tastes!! So.....my question is, can a single barrel carb work on our engines in this arrangement?

 

[Steve83]

Hey Westgl, very nice work there! Joe is quite the inspiration for us all - we're so fortunate to have him on the forum!

Regarding your vacuum advance, I don't think it will work simply by tapping off the manifold. The advance port in the carb is just behind the throttle plate, and little, if any vacuum is present until you open the throttle. By using manifold vacuum, you will have full advance at idle and coasting, and less advance under load. Just a thought...

 

[westgl]

Hmm OK,

I wonder if a mechanical bell crank or a second cable, hooked into the throttle cable, that advances with the throttle would work.

Well I wonder how they are advancing the timing with the Juan fenandez and the LDwingnut, manifolds.

 

[westgl]

There is a Russian guy named Sergey he uses the Juan Fernandez conversion and a Solex 34pict3

https://www.youtube.com/watch?v=rSq6PzDpxUE

 

[westgl]

Joe are you referring to a Mixture screw covered on the carb. from the Manufacturer

Not including the Idle adjustment screw

I see 1 adjustment screw, it is in the base of the carb.

Do you have more than just one adjustment screw, i do see several blocked holes with brass plugs in them

 

[westgl]

There are 3 total vacuum lines coming off of the carb.

I am not sure which one would be correct for vacuum advance duty.

 

[dan filipi]

Just arrived today.
$75 including shipping:

I have a manifold on the way.

I'm anxious to start this install but C5 ignition comes first.