Dialing in dual webers, San Diago'ans, in need help! Options

[neil30076]

1.7 with big bore to 1911cc, 2 x 40 IDF's and CB linkage - problem is that the linkage design is such that you can never set it up right so that both carbs stay in mechanical sync from closed to full - the linkage design will not allow it - so how do you set it up - does anyone have a perfect setup I can see - or come and help me set up mine - beer, etc on me! Engine is out so its an easy access :-)

Yes, I am a mechanical engineer and i did do a lot of research on the linkage design!

[sean_v8_914]

that linkage works just fine. are you sure you got the type 4 version?

[sean_v8_914]

fdhfdh

[sean_v8_914]

fgdf

[sean_v8_914]

xcgds

[neil30076]

that linkage works just fine. are you sure you got the type 4 version?

Sean, i bought this as is, and am now trying to sort it out - it looks like your diagram, the linkage on 3/4 is much longer than 1/2. At idle, they are in sync, at full the 1/2 is 1/8th inch off the end stop.

[sean_v8_914]

jmhf

[sean_v8_914]

xcbv

[sean_v8_914]

here is where they tend to get buggered up. since the carbs are offset left to right, teh linkage can be off angle on one carb. some kits have teh offset built into the cross bar pivot...some dont. the angle on teh down arm from teh lever to carb must be equal in both left/right and fore/aft.

here is one way to correct it

[neil30076]

Ah, my linkage is on bulkhead side of ending not the transmission side! AKA a VW setup, maybe! It was running fine, except for backfiring on overrun :-)

[neil30076]

here is where they tend to get buggered up. since the carbs are offset left to right, teh linkage can be off angle on one carb. some kits have teh offset built into the cross bar pivot...some dont. the angle on teh down arm from teh lever to carb must be equal in both left/right and fore/aft.

here is one way to correct it

That exactly what i was planning on doing - CB does not have the offset - - a buddy of mine has access to CAD design and AL welding, se we were planning on creating a 'kit' to fix!

[neil30076]

here is where they tend to get buggered up. since the carbs are offset left to right, teh linkage can be off angle on one carb. some kits have teh offset built into the cross bar pivot...some dont. the angle on teh down arm from teh lever to carb must be equal in both left/right and fore/aft.

here is one way to correct it

That is an easier way to fix, we were going to move the fulcrum arm / point :-)

[sean_v8_914]

does it run? bring it down to the shop. I have many little problem solving 914 nuggets. we'll get her square.
6233 university, its just past college ave. always call first, of course

[neil30076]

does it run? bring it down to the shop. I have many little problem solving 914 nuggets. we'll get her square.
6233 university, its just past college ave. always call first, of course

Sean,
I hope to get the engine back in in the next day or so - and i will call you - I also have a 928 to drop the a/c pump back in - fortunately I have 2 land rovers that do run right now :-)

[sean_v8_914]

cool. show us the car!!!
did ya need anymore pics? I'll have a dual carb car at teh shop wed if ya want to swing by to play with the linkage.
I have a car at the shop that runs teh center pull type linkage. I'll take some pics to post tomorrow.

[johnnie5]

Yes, the 'spacer' in the linkage is a good call. Its funny how much of a problem the uneven linkage can create. Go to Seans shop, he will get you dialed in.

[neil30076]

cool. show us the car!!!
did ya need anymore pics? I'll have a dual carb car at teh shop wed if ya want to swing by to play with the linkage.
I have a car at the shop that runs teh center pull type linkage. I'll take some pics to post tomorrow.

Thanks Sean, i'll plan on dropping by on weds ( i'll call first) ,I would like to see the setup first hand anyway. I'll shoot some pics and send ahead so you can see what i'm dealing with.

[McMark]

That linkage won't work on the 'transmission side' if you still have rear trunk torsion springs. Hits on the passenger side.

That welded linkage looks familiar. (IMG:style_emoticons/default/cool.gif)

I think crossbar linkages are dumb.

[neil30076]

That linkage won't work on the 'transmission side' if you still have rear trunk torsion springs. Hits on the passenger side.

That welded linkage looks familiar. (IMG:style_emoticons/default/cool.gif)

I think crossbar linkages are dumb.

Thanks Mark - I fabricated an extension for the arm on the throttle shaft, hooked it all up and now they sync mechanically, at least on the engine on the bench. Now all I need is to get it welded up with a piece to strengthen it. I'm going to drop by Sean Malloy and check out a couple of carb setups he has in shop to make sure i'm doing this right! No torsion springs, gas struts on trunk! Pic attached with extension in place, also the car after respray.