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-   -   Intermittent flooding (https://www.rx7club.com/1st-generation-specific-1979-1985-18/intermittent-flooding-973832/)

silverchris 10-19-11 01:06 PM

Intermittent flooding
 
Hi all,

I am having somewhat of a problem with my carburetor. Most of the time the float levels are fine, but if you let the car idle for 10 or 15 minutes, one or both of the float bowls full up completely with gas and flood the car. It feels like it can be resolved by give the carb a few light taps, but the issue keeps repeating itself. The carb has been rebuilt by me recently, but everything seems to check out ok.

The car isn't on the road yet so I am not sure if it would have any symptoms while on the road.

So far I have verified the fuel system is unmodified, the gas tank vent is clear, and the carb check valve in the return line seems to be functioning normally.

Any ideas would be appreciated

DivinDriver 10-19-11 02:19 PM

This is a common problem with recently-replaced needle valves; they tend to hang up in the bores, sticking open.

They wear in pretty quickly, or you can remove them and burnish the outside edges slightly.

Oneiros 10-19-11 10:47 PM

Yep this will almost always happen on a fresh rebuilt carb unless you smooth out the needles. Taken from Sterling's site:


Before installing the needles, here's a tip that can help you avoid needle the binding that causes the flooding that so often follows a fresh rebuild;

The seats have very small, nearly microscopic concentric tooling marks on the inside. Again, on a microscopic level, this makes for a very rough surface that's not conducive to having another brass part slide easily across it's surface. While there's not much we can do about the inside of the needle seats, we can do something to the needles themselves to decrease the friction as they move in and out of the seats. The seats are not polished inside, but the surface is at least consisten t, and there is no way to polish the insides to that same consistency, even with my watchmakers lathe. Please do not try. While polishing the insides of the cylindrical needle seats sounds like a great idea, it's a fruitless, messy effort that won't yield results worth the time. They can even end up sticking worse.

But what you can do that's very quick, easy & effective, is burnish the four corners of each needle. The needles are "tumble polished" after they are spit out of a manufacturing machine, and as a result they have a matt finish. This is where the friction comes from.

Coat the outside of the needle in about a finger-print's worth of oil, and take something small and highly polished and lightly rub it along the shaft on each corner very lightly. You should start to see the corner get brighter. This is burnishing the surface, and it's the same as "breaking in" the part. Try not to rub hard as that can cause tiny gouges in the surface, defeating what your trying to accomplish. All in all, this process should need more than about 4 or 5 minutes, but it can save an hour or more of aggravation later on.
I couldn't get this to work so I lightly scrape the corners off with a razor knife. Works every time. :)

silverchris 10-20-11 12:03 AM

1 Attachment(s)
I followed sterling's guide but wasn't sure what he meant by that section. I am guessing the parts I circiled in red are what I should be scraping lightly with a knife or rubbing smooth on a machined surface?

Oneiros 10-20-11 09:20 PM

1 Attachment(s)
No, you want to smooth over the corners of the whole square shaft, the yellow parts

https://www.rx7club.com/attachment.p...1&d=1319163553

silverchris 10-21-11 12:50 AM

well... that would explain were I screwed up. Will give it a shot.

Thanks


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