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#92841 - 11/05/17 03:45 PM 230 2bbl mod for weber 38x38
70Nova Offline
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Registered: 05/06/11
Posts: 374
Loc: Va
Long story short....

Hogged out stock intake hole, went clear through the wall and into the exhaust heat cavity behind.





Made a steel sleeve to slip inside to make a solid wall again





Brazed the sleeve in place, drilled and tapped the 4 surrounding casting bumps, and had a machine shop mill the surfaces flat and to the exact same height



Made skinny barrel nuts for the studs, the two bigger ones were Porsche 911 exhaust nuts, drilled and tapped to different thread size and reduced OD. They have a convenient 6-point Allen head at the end. The 4 smaller barrel nuts were brake line flare nuts, drilled and tapped and hex reduced to 10mm for extra clearance.



Got a block of aluminum to make a carb adapter out of, for the Weber 38/38 clone







bolted the sucka on with the recessed nuts



sandblasted the manifolds



Painted them too


[img]http://sm.uploads.im/t/jmO6p.jpg[/img]


and replaced all studs with new. Currently waiting to find time to hang them on the car. Left a piece of aluminum sticking out of the adapter for now, in case I need to use it to fabricate a throttle cable bracket or something. Haven't thought that far yet, I'll burn that bridge when I get to it I guess.

Factory carb hole on the intake grew surface area by 46%, roughly the same amount the carb bore grew going from stock single barrel to two 38mm. The carb is a true 2bbl, butterflies open simultaneously.

I suspect this engine will make much more exhaust heat than needed to heat the intake, so I will be using the block-off LPG gasket between the exhaust and intake, and rely on conducted heat only.

Next step would be headers so this is not permanent.


Edited by 70Nova (11/05/17 05:15 PM)

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#92843 - 11/05/17 05:50 PM Re: 230 2bbl mod for weber 38x38 [Re: 70Nova]
stock49 Offline

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Registered: 04/09/03
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Loc: Medina, Ohio USA
I like the fab work. It's nice when modifications look like they belong there. The allowance for the linkage is thinking ahead. Prevents a second iteration on the fab. Once the linkage is sorted I would bolt the carb to the adapter and trace around the base with a sharpie. You should be able to lose the excess metal from the adapter and make it look like the manifold was cast as as a two barrel.

If you decide to go for headers - a heat plate can always be added.

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#92844 - 11/05/17 06:00 PM Re: 230 2bbl mod for weber 38x38 [Re: 70Nova]
70Nova Offline
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Registered: 05/06/11
Posts: 374
Loc: Va
I plan to do the sharpie trace and cut it down, yes. I wanted to leave a little extra all over, in case I need it.... much harder to put it back on later laugh Headers may be on the to-do list next summer. For now I just want to see how it runs like this.

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#92863 - 11/08/17 10:45 AM Re: 230 2bbl mod for weber 38x38 [Re: 70Nova]
70Nova Offline
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Registered: 05/06/11
Posts: 374
Loc: Va
If memory serves, hole went from 45mm to 55mm. If anyone was wondering.

38mm area = 1134mm2 x 2 =2268mm2

45mm area = 1590mm2

55mm area = 2375mm2

hope I got that right laugh

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