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As for starvation on the test runs, you might be chasing a dirty filter/clogged pickup/weak fuel pump/bad line issue like the rest of us. I would put a couple miles on it like you're doing with your test run, then make sure the ignition is all in spec, then timing, and then check your idle mixture and set your idle again and see how she does.

If she's off after that, start checking fuel pressure headed into the carb. That's how i discovered that something fishy is going on with my fuel.

Sam,

The hole in your manifold and that in Cortcomp's manifold certainly look the same. As long as there is no blow-through from the hole to the hot box area it should not be a problem. Hope this is the case as it'll certainly save you a lot of time, effort and worry. Looks like I panicked in the light of some manifold problems I've seen over the last few years.

The carb is on my 4 bbl now or else i'd check it, but i'd swear it had the same hole. I wonder how they even made it, if it was a cast piece that was done poorly or what.

Multi barrel carbs and multi carb setups need a balance passage or tube to equalise vacuum for a smooth idle. Usually there is a small passage in the base of the carb or in the top surface of the manifold. See if there is a notch between the barrels on the bottom of the carb. If not the hole may be the balancer.

Mal, chin up, chest out!

1970s VW Beetle 1302 inlet manifold


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Gerd, I can't see if that's a deliberate cut or a burn thru. But multi-barrel carb installations all have some provision for balance between the barrels or the manifold branches. Could be within the carb base or in the gasket, others in the manifold. In the case of the Hudson Hornets with the Twin H (2 Carter WA-1 carbs)Power the balance tube was a long tube external to the manifold connecting the front 3 branches with the rear 3.

Dave, that's a deliberate cut. In case of extra tubes it is called Str?mungsangleicher, I would translate it as "airstream equalizer". The intention for the unusual looking shape of the cut in Sam's manifold is to swirl the air.





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My '51 also has the hole. It is not centered between the chambers. I can feel the empty cavity between the holes and the holes do not "feel" the same size. Seems like they broke a hole between the chambers and size or where they lined up did not matter.

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Well, I have to apologize for starting this whole hole thing because with only a quick second look, I would have noticed that it's a plugged drilled hole (by design), with no corroded openings into the heater box. >>Sorry for the False Alarm<<

Also the "sluggish" carburetor performance was found to be mostly the float setting. The rebuild kit spec sheet called for 1/4" but other resources called for 5/32", which did improve the performance but it's still not 100%. Speaking of the rebuild kit, it came with a Daytona type float valve that has a flat tip vs. the normal pointed needle. Does anyone have any experience (good or bad) with this type needle and seat? ... And yet, another opportunity. Further trouble shooting found the vacuum advance not working because of a "frozen" distributor shaft around the mounting bracket couldn't pivot. The diaphragm was leaking to boot. Hopefully this vacuum fix will help me get the carb problems adjusted out.

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Hah! How none of us caught that before this point.... It makes sense though, you'd want any vacuum device to see total manifold vacuum, not just a reading off of one side.