Weber 34 DMSA - Rebuild Question

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mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Weber 34 DMSA - Rebuild Question

Postby mbeer » Wed Jan 10, 2018 9:03 am

I recently acquired a 34 DMSA and single plane manifold to replace the DHSA I am currently running. In the process of cleaning and rebuilding the DMSA I noticed the underside of the carb top seems to be missing several brass pieces/nipples...one is still in the carb top, one is stuck in the body of the carb, and two seem to be missing... (see photos). The underside of my DHSA carb has all of these fittings in place. So....

What are the brass fittings shown in the photos?

Are they crucial to proper operation of the carburetor?...if so can they be sourced and where?

Any tips for getting the fitting that's stuck in the carb body out? (see photos)

Image
Image
Image

URL Link:
https://imgur.com/3JHkm42
https://imgur.com/TJqADZ9
https://imgur.com/eqt9gSy

Any knowledge of these pieces you could share would be appreciated!

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aj81spider
Posts: 1160
Joined: Fri Mar 11, 2011 9:04 am
Your car is a: 1974 Fiat 124 Spider
Location: Chelmsford, MA

Re: Weber 34 DMSA - Rebuild Question

Postby aj81spider » Wed Jan 10, 2018 5:00 pm

I don't know what they are used for, or why they are there. However I rebuilt two DMSAs and both were exactly like yours, so I believe your DMSA is correct and normal.
A.J.

1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)

mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Re: Weber 34 DMSA - Rebuild Question

Postby mbeer » Wed Jan 10, 2018 5:12 pm

Thanks A.J. all seemed to operated well with your DMSAs after the rebuilds? Did you happen to source a fast idle diaphragm when you rebuilt yours?...where did you find this at? Or did you just remove the fast idle and cap it?

Thanks,

Mark

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aj81spider
Posts: 1160
Joined: Fri Mar 11, 2011 9:04 am
Your car is a: 1974 Fiat 124 Spider
Location: Chelmsford, MA

Re: Weber 34 DMSA - Rebuild Question

Postby aj81spider » Thu Jan 11, 2018 7:27 am

I think Midwest Bayless has them:

http://www.midwest-bayless.com/p-7322-fast-idle-module-assembly-weber-dmtra-dmsa-oe-nos.aspx

The kit I bought only had the accelerator pump diaphragm, and the fast idle's looked OK, so I left the originals in.
A.J.

1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)

mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Re: Weber 34 DMSA - Rebuild Question

Postby mbeer » Thu Jan 11, 2018 9:02 am

aj81spider wrote:I think Midwest Bayless has them:

http://www.midwest-bayless.com/p-7322-fast-idle-module-assembly-weber-dmtra-dmsa-oe-nos.aspx

The kit I bought only had the accelerator pump diaphragm, and the fast idle's looked OK, so I left the originals in.


Ok, great. Any idea where the choke pull off assembly gets plumbed to? I'm assuming a vacuum line connects from pull off assembly to somewhere on the manifold?...or maybe to one of the two ports on the DMSA base (the ones by the idle mixture screw). Thanks for your help.

mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Re: Weber 34 DMSA - Rebuild Question

Postby mbeer » Thu Jan 11, 2018 9:20 am

Also, did you install a base plate insulator beneath and above your base gasket/spacer?

This is what I am referring too...

https://www.midwest-bayless.com/Fiat-12 ... a-new.aspx

It seems unnecessary as the basket plate has the paper gaskets on each side...but maybe it serves a purpose I am unaware of.

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aj81spider
Posts: 1160
Joined: Fri Mar 11, 2011 9:04 am
Your car is a: 1974 Fiat 124 Spider
Location: Chelmsford, MA

Re: Weber 34 DMSA - Rebuild Question

Postby aj81spider » Fri Jan 12, 2018 9:08 am

I'm no expert, so if anyone gives you an alternate opinion feel free to take theirs.

I'm not sure what you mean by choke pull off assembly - mine has a manual choke with a cable to a knob under the dash. That said both vacuum ports on the base of the carburetor (on either side of the idle mix adjustment screw) are capped on my setup.

I did not put an insulator above my gasket, just mounted the carb to the intake manifold. I haven't had any issues with that.
A.J.

1974 Fiat 124 Spider
2006 Corvette
1981 Spider 2000 (sold 2013 - never should have sold that car)

mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Re: Weber 34 DMSA - Rebuild Question

Postby mbeer » Fri Jan 12, 2018 9:54 am

aj81spider wrote:I'm no expert, so if anyone gives you an alternate opinion feel free to take theirs.

I'm not sure what you mean by choke pull off assembly - mine has a manual choke with a cable to a knob under the dash. That said both vacuum ports on the base of the carburetor (on either side of the idle mix adjustment screw) are capped on my setup.

I did not put an insulator above my gasket, just mounted the carb to the intake manifold. I haven't had any issues with that.


Thanks A.J. - I appreciate all of the insights. My 72' also has a manual choke...I figured out the choke pull-off assembly (the assembly directly above the idle idle mixture screw)...As I understand this is supposed to open the choke plates should they be closed during acceleration so they engine is not staved of air. On my DHSA there is a vacuum line that runs from this piece to the secondary diaphragm, which lead me to believe the DMSA would have a similar setup, albeit w/o the vacuum secondary ...but now I see there is no external plumbing for this piece and that it draws vacuum from the carb body (piece that relieves the tiny O-ring). Thanks again for the help.

Mark

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xjware
Posts: 87
Joined: Wed Aug 31, 2011 8:29 pm
Your car is a: 1978 124 Sport Spider
Location: Fishers (Indy), IN

Re: Weber 34 DMSA - Rebuild Question

Postby xjware » Fri Jan 12, 2018 11:09 am

Mark, where you at in Indy? Do you know about our local club? https://www.meetup.com/Central-Indiana- ... at-Lancia/
1978 124 Spider
Central Indiana Italian Car Association
http://www.ciica.me/

mbeer
Posts: 9
Joined: Thu Sep 01, 2016 1:47 pm
Your car is a: 1972 Fiat 124 Sport Spider
Location: Indianapolis IN

Re: Weber 34 DMSA - Rebuild Question

Postby mbeer » Fri Jan 12, 2018 11:47 am

xjware wrote:Mark, where you at in Indy? Do you know about our local club? https://www.meetup.com/Central-Indiana- ... at-Lancia/


Troy, we are in Broad Ripple area. I am actually signed up as a member!...Just have not had the opportunity yet to make it to an event. Hope I can do so come this spring!


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