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Phenolic Spacer Question

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Hi All, quick question regarding phenolic spacers.  I have a 32/36 w/ a stock unmodified manifold.  In my spacer research I can't seem to find any that have the matching holes for the carb and manifold as they all come in the peanut shape.  I'm wondering A. if I go ahead and put a peanut shaped spacer onto a manifold that has not been hogged out, will it cause problems in fuel/air mix and delivery and B. does anyone know where I could get spacers w/ separate holes to match?

 

Thanks!

Adam

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From a long time ago...Ford Pintos (shudder!) used a 32/36 Holley-Weber carb (the Ford dealer was where I bought Weber jets back in the day) that IIRC had a two-hole phenolic spacer.  You might try an auto parts store to see if they're available.  Also try the usual Weber sources.  I know they exist 'cause I've seen 'em.

 

mike

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I had the same concern with the gasket that came in the rebuild kit.  I traced it and made a two hole gasket.  A previous owner had done some grinding on the manifold, but I made it match the gasket opening.  Similar to what you are up to, just a thinner example.  I am running without the spacer, so I am interested in what you find out.

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I was asking about that when I rebuilt my weber and got these answers:

 

 

Conventional wisdom is don't peanut just taper/ enlarge the holes to match the throats of the carb. Peanut-ting may slow the speed of the charge too much by increasing the plenum volume below the carb.

 

 

 

 

+1 Finally there is a guy that understands what a sudden enlargment in an air stream does. It also causes fuel to recondense. Flow bench testing a manifold alone does not tell the whole story. The flow bench test should be done with the carb installed both before and after peanutizing. And if the test aparatus is good enough, the after peanutizing results will be worse because of the sudden enlargement effect on the flow dynamics (it's another fitting loss coefficient in the air stream.).

 

 

 

 

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What those two posts from 2012 fail to recognize is that peanut-shaped intake manifolds actually came like that from the factory (I'm not sure which year, carb model, however). Personally, I think our German buddies were pretty smart, and shaped the opening that way for a reason.

 

Here's an anti-vibration mount (and insulator) I sell for the 38/38, for racing/custom applications. -KB

 

 

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My original spacer (early 80's) had two holes, but had to be modified so the holes in the carb and manifold aligned.  Thus the design for the peanut shape which is the current preferred design.

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From a long time ago...Ford Pintos (shudder!) used a 32/36 Holley-Weber carb (the Ford dealer was where I bought Weber jets back in the day) that IIRC had a two-hole phenolic spacer.  You might try an auto parts store to see if they're available.  Also try the usual Weber sources.  I know they exist 'cause I've seen 'em.

 

mike

 To echo what Mike stated, look for the rebuild kit for the Holley-Weber 5200 (licensed by Holey, Secondary and Primary venturis were reversed).  When I was a starving college student and could not afford a Weber 32/36, I went down to one of the large salvage yards in Tampa.  They had a bin full of used 5200 for $5.00 each.  I got the best I could find, stopped by the local NAPA bought a rebuild kit for $10.00 and was good to go.  Drove my 2002 like that until I graduated and received my commission as a 2LT US Army.......

Earl

74 02Lux  now with 2xMikuni 44PHH

02 M Roadster

72 Volvo 1800ES

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What those two posts from 2012 fail to recognize is that peanut-shaped intake manifolds actually came like that from the factory (I'm not sure which year, carb model, however). Personally, I think our German buddies were pretty smart, and shaped the opening that way for a reason.

 

Here's an anti-vibration mount (and insulator) I sell for the 38/38, for racing/custom applications. -KB

Do you have a photo of an unmolested intake with a BMW roundel on it?  I don't think so.  The physics of air flow in Germany is the same as here in the USA.  Go down to your local college and consult any ME prof and see what he says.  I thinks it's fluid mechanics 201.

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Do you have a photo of an unmolested intake with a BMW roundel on it?  I don't think so.  The physics of air flow in Germany is the same as here in the USA.  Go down to your local college and consult any ME prof and see what he says.  I thinks it's fluid mechanics 201.

 

We discussed this point (off line) during the original thread, at that time I sent you photos of a BMW-part-numbered 'peanut' intake which showed no signs of having been molested. Check your email records. (note: I'm neither saying nor pontificating  that the peanut manifold is better, or not better .... but rather, I believe those who claim the manifolds were not provided by the factory are, quite-possibly, mistaken). -KB

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Don´t know if I do understand right. The discussion is about this

 

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and that

 

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?

 

Regards, Lars.

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A peanut manifold may improve flow over the two hole manifold as it will direct flow of the secondary butterfly towards the intake runners. Ideally the two hole would stay in place but the bottom of the holes would be radiused (instead of the sharp angle that they come with), but for a manufacturer this cannot be easily accomplished as it would require additional machining or an operator manually porting. The peanut shape, although not ideal, is likely an improvement over the two hole, and because it is easy to machine it is seen in the later intake designs.

 

If you took the time to do things yourself, the overall best flow characteristics you would see would be with a two hole system, port matched to the carb, with the holes having a nice radius on the edge closest to the head. 

 

If you take a fluid mechanics class you would understand why in depth, but an hour on google will provide you with enough of an idea of how air moves to give you a general idea. 

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Regarding finding phenolic spacers, Mike is correct in his reference to Pinto's using essentially the same carb.  I'm pretty sure Jeeps of that era use it too.  Jeep part probably costs 7 or 8 times the cost of Fort part.

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