Front SU Carb pulling in a TON more air than the rear - Help...

[research monkey]

Anyone have recommended vendors in the US for specific parts on an SU carb? 

[siteunseen]

I've always bought from ztherapy.

I do have another SU place bookmarked on my laptop. I'll post it when I'm using again. Most likely tomorrow though...

Edited July 16, 2020 by siteunseen

[dutchzcarguy]

I see a big hole round the needle here !!! (TOP PIC!)  were the other has not!  (compare this lower pic with the other one)  youre missing a part here? The carbs with the part missing round the needle sucks less air?  let us know!  (Can't believe no one saw this?)

[Patcon]

That looks like the top of the jet. One is much lower than the other. I don't recall if you have set the floats yet, but if you haven't that is where I would start

[Captain Obvious]

4 hours ago, dutchzcarguy said:

I see a big hole round the needle here !!! (TOP PIC!)  were the other has not!    (Can't believe no one saw this?)

As Patcon mentioned, the "hole" you are seeing in that pic is simply the jet needle dropped down out of sight. It's normal operation if the choke is on or if the nozzle has been adjusted down to affect the fuel ratio.  It's not the problem here.

But while I'm in here there are a couple things I wanted to ask about...

First, what's the deal with that one carb with all the gouges and marks on the venture bridge? That thing is hammered!! Like the slide piston was stuck down at one point and someone stuck a screwdriver in there and tried to pry it up or something?? Probably doesn't make much functional difference, but those marks really show evidence of mistreatment in the past.

Other question is... There are small (1/8 inch-ish?) holes in the bridges that are intentional. I assume they are 72 specific.

Where do those holes go?  :

 

 

 

[Terrapin Z]

Some SU info and parts from down under. 

https://sumidel.sitesuite.net.au/shop/category/carburettor-spare-parts

[research monkey]

2 hours ago, Captain Obvious said:

As Patcon mentioned, the "hole" you are seeing in that pic is simply the jet needle dropped down out of sight. It's normal operation if the choke is on or if the nozzle has been adjusted down to affect the fuel ratio.  It's not the problem here.

But while I'm in here there are a couple things I wanted to ask about...

First, what's the deal with that one carb with all the gouges and marks on the venture bridge? That thing is hammered!! Like the slide piston was stuck down at one point and someone stuck a screwdriver in there and tried to pry it up or something?? Probably doesn't make much functional difference, but those marks really show evidence of mistreatment in the past.

Other question is... There are small (1/8 inch-ish?) holes in the bridges that are intentional. I assume they are 72 specific.

Where do those holes go?  :

 

 

 

Here are a few photos I just took.  

Edited July 18, 2020 by research monkey

[research monkey]

And it was definitely the throttle shaft butterfly.  Looks like the previous owner he-man'd them on there (even looks like they used larger screws and retapped?).  They also don't line up and are slightly offset of eachother. 

[siteunseen]

I agree! 

@grannyknot

Oh yeah, @Mike

 

Edited July 18, 2020 by siteunseen

[Captain Obvious]

9 hours ago, research monkey said:

And it was definitely the throttle shaft butterfly.

Wow!! That's some fine PO workmanship you got right there! Yeeesh!

So when you said you swapped over to the old carb... Are you thinking you're going to repair the PO hammered one, or just keep running the other? Is there something wrong with the other one that made you want to run this one instead?

And thanks for the pics of that mystery hole, but unfortunately I'm still unclear where that hole goes. It's definitely a 72 specific thing and unfortunately I don't have a pair of those here to poke around with. Thanks again though!

[Captain Obvious]

And please tell me you weren't the one that painted the carbs, right? That was the PO?   

[research monkey]

45 minutes ago, Captain Obvious said:

Wow!! That's some fine PO workmanship you got right there! Yeeesh!

So when you said you swapped over to the old carb... Are you thinking you're going to repair the PO hammered one, or just keep running the other? Is there something wrong with the other one that made you want to run this one instead?

And thanks for the pics of that mystery hole, but unfortunately I'm still unclear where that hole goes. It's definitely a 72 specific thing and unfortunately I don't have a pair of those here to poke around with. Thanks again though!

The car currently has the old front carb and the "rebuilt" carb in the rear.  I was going to try to pull the butterfly and throttleshaft from my old one to swap over to the "rebuilt" one but the screws holding in the butterfly are wanting to strip.  

I originally purchased the rebuilt set because mine have a lot of surface rust / corrosion.  Pretty sure they are the original set and the previous owner lived a block away from the ocean. Basically, I saw a set of pretty ones online that were noted to be freshly rebuilt so I did that instead of pulling the old, cleaning, polishing, cleaning, and rebuilding my old set. 

Oh, and no, I didnt paint them, the PO did ?