Hey there

Just wondering if anyone can tell me wich would be the issues that undercarburetion can cause. I've read plenty of things (and experienced, he) on overcarburation, but I found nothing on the pathologicall extreme on the other side.

thnx

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Undercarburetion tends to cause the engine to reach a particular speed and then stop increasing in RPM/power as the airflow and fuel feed limits of the carburetor(s) are reached. An example would be Doc's monster 260CID slant-6, about which he says:

"On-the-road performance of this combination is impressive, especially the off-idle to 3,000 RPM range. My best description of the feel of this engine is that it reminds me of an average-running 273 2bbl V8 in the 600 to 3,000 RPM range. After 3,000 RPM, I get the feeling of an undercarbureted engine. It just stops pulling hard as it continues to rev up. At about 4,800 RPM the power really starts to fall off." (taken from this article).

If you think about it, you can "undercarburete" any engine -- simply don't open the throttle more than a crack. The engine will accelerate to a certain point and not go any faster. As you open the throttle wider and wider, this allows more and more airflow and the engine goes faster and faster, developing more and more power, until your foot is on the floor and the throttle plates are wide open. Then, assuming the manifold still has additional flow capacity, the carburetor itself becomes the limiting factor. RPMs will continue to increase somewhat but power will fall off, then RPMs will stop increasing.

aha! I'm undercarburated. I don't mind since I'm prepairing my car for a 2 bbl setup that's goin to be bolted in in about 1 week or so.

_________________
Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.