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32/36 Weber on a 38/38 Manifold


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Tom and Simeon and Jim,


"...enlarge the holes to match the throats of the carb."

Does this advice apply to both 32 and 38 carbs?  Reason I ask:  I have seen many recommendations to open the intake to accommodate both barrels of a 38 carb.  Certainly, enlarging two holes will be easier than hogging out a lot of metal between the holes.



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Ideally, you'd open the mating face of the manifold to provide a smooth transition from the

carb into the manifold, and then blend that opening down into the plenum smoothly.


That's really hard to do, as you can only work from the top down.


And you want to be able to plop a 38 onto it as well.


So your next bet is to mate it to the 38, and then smooth THAT out a bit so that

it provides unimpeded flow into the plenum.


Jim's right about flow.  The caveat, tho, is that the engine's drawing from 4 ports sequentially, so 

the flow's interrupted pretty radically.  The practical effect of this is there's more fuel dropout to different

cylinders at different rev ranges, as the harmonics in the plenum change. 

The 'peanut' is reputed to change less, despite its

less- ideal shape, as the flow direction's less pronounced.


Does ANY of this matter?


Not really.   


If you're going to eventually use this as a 38 manifold, open it out for that, and be happy.

If you were using this car competitively against others with the same restrictions, you'd want

to maximize it, but you're just not going to notice the horsepowers or foot/pounds differences 




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"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Thank you, guys.  Excellent discussion and advice.  Questions and concerns have been answered and addressed, respectively. 


Thanks, Toby, for summarizing the key answer:  If you're going to eventually use this as a 38 manifold, open it out for that, and be happy." 


I will  modify to accommodate a 38/38, try a 32/36, evaluate, and +/- move on to a 38/38, evaluate, and +/- move on to dual 40's.  Each carb-manifold mod combo will be evaluated to determine if it satisfies my carnal automotive desires and/or my inner 2002 chakra.


Will report.  Stay tuned.  News at 11:00.




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