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Swapping carbs from Zeniths to Webers
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BK911
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PostPosted: Tue Jan 12, 2016 12:14 pm    Post subject: Swapping carbs from Zeniths to Webers Reply with quote

Hello guys!

I have a '64C with an unknown engine with no number stampings.
I was told it was a 912 engine but it has the 32mm Zeniths and unvented heads.
From limited research, the Cs, SCs and 912s all had the same spec heads.
The only difference is the cams, compression ratio, and carb size.
The cam part number indicated it was an SC/912 grind.
So could I swap out the zeniths and manifolds for a set of split shaft webers and manifolds and see a noticeable increase in power?
Is it worth doing?

Thanks!!
BK
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doublecabmel
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PostPosted: Tue Jan 12, 2016 12:39 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

This is a popular mod. The bigger engine can handle the bigger carbs and they usually run better. Also you can sell your Zeneths and come out ahead
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BK911
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PostPosted: Tue Jan 12, 2016 6:01 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Thanks Mel!!
What do you mean by larger motor?
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Craig Richter
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PostPosted: Wed Jan 13, 2016 9:57 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

BK, C's came with Zeniths. The cam and compression and carbs are well matched to make a smooth-running street motor. If you want more power with Webers, you should change cam, CR, maybe add big-bore kit. Be prepared to rev it a little higher. By the way, there are no split-shaft Webers; that's a Solex 40P11 thing.
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BK911
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PostPosted: Wed Jan 13, 2016 11:43 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Thanks Craig. I meant solex, just had webers on my mind.
The cam is a sc/912 grind.
Engine runs fine, but have the solex on a shelf so wondering if its worth swapping out.
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Craig Richter
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PostPosted: Fri Jan 15, 2016 10:18 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

You say your motor runs fine now, so why mess with it? The power increase wouldn't be that great considering the amount of work (and probable de-bugging) involved. You could likely sell the Solex for more than the Zeniths if that's a consideration. Then you could fix your generator. Have fun.
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BK911
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PostPosted: Fri Jan 15, 2016 3:42 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Thanks Craig.
Yea she runs fine, but if I can spend a day and make her run better, why not?
The Sc had about 15 more HP than the c?
I already have the cams.
Same head ports and valves.
Thought I could swap out the carbs and get 10 - 15 HP.
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Craig Richter
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PostPosted: Fri Jan 15, 2016 9:10 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Yeah, that sounds about the right increase, and you will definitely notice that much more hp. I get the impression you like to tinker, so if you have all the parts, have fun Cool
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dsrtfox
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PostPosted: Sat Jan 16, 2016 9:19 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Surprisingly nobody has brought up the fact that your 50 year old Solex's are more than likely wore out which means they need machining on throttle shafts and throttle bores. This operation costs between $1,000 and $1,600.
I went to Weber's a few years ago and never looked back. Total cost was about $700 including brand new carburetor's. JMHO
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PostPosted: Sat Jan 16, 2016 7:07 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Good point from dsrtfox. The reason I first answered this post was because Webers were mentioned. I love Webers. Very Happy
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ozzo
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PostPosted: Sun Jan 17, 2016 8:43 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

I have exactly the same. A c with sc cam and both carb set up.
zenith with 24 venturi are a pain... really lack power. Zenith with 29 venturi are the best from 2000 to 4000 rpm.... solex are the best over 4000 rpm seems they pull forever but little less power until 3000rpm.

Solex also means a little more noise while driving, zenith air canister are quiter
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BK911
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PostPosted: Mon Jan 18, 2016 3:25 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Excellent feedback ozzo.
I was curious about low rpm performance with the larger carbs.
Plenty of other projects on the list; this one will get shelved for a bit.
May sell off the split shaft solexs since I doubt I will use them.
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saddlesore1
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PostPosted: Fri Feb 12, 2016 4:33 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

you will love the swap. I got tired of the needle valve sticking and the entire gas tank filling the motor and mixing with the oil. Very Bad for the barrings and other parts. Anyway, much better throttle response and snappier. You will have to research jetting until you find the right combo. The swap right out of box will most likely have a bad flat spot which jetting will correct. Save the old carbs in the attic. They increase in value every day.
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BK911
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PostPosted: Tue Jan 17, 2017 10:31 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Hey guys,

I finally started tearing down the *new* Solex carbs to rebuild, and noticed a very slight wiggle in the throttle shaft.
How much is too much?
Not much play, but enough to notice.
And only on the linkage side, the other side feels nice and tight.
If I do need to get the shafts redone, any recommendations?

Thanks!!
BK
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PostPosted: Tue Jan 17, 2017 3:11 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Check and see if the throttle blades are digging into the throttle bores. If so they need re manufacturing not rebuliding. If the damage is slight they will still tune and run fairly good.
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badsix
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PostPosted: Fri Jan 27, 2017 12:14 pm    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

sell the Solex's and buy new Weber's bolt them on and have fun
Jay D.
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MoPor
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PostPosted: Sat Jan 28, 2017 8:12 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

or buy a pair of Dellorto 36DRLA Smile
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Starbucket
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PostPosted: Thu Feb 02, 2017 9:04 am    Post subject: Re: Swapping carbs from Zeniths to Webers Reply with quote

Make sure the rubber block on the split shaft adjuster is still there otherwise your idol will impossible to set as the butterfly on the bore farther from the linkage will open slightly by the vacuum at idol.
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