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Simple SU Carb Question. Please help


COmputoman

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At medium to highway speeds when I let off of the accelerator quickly my cab is filled with a nasty fuel smell. This can get pretty harsh and creates an unpleasant drive. Ive checked the exhaust system and pretty confidently ruled this out to be the main cause of the issue. One thing that does concern me is the fuel bowl breather tubes. After talking to a few folks at a localz repair shop and looking at photos on the web I determined that these are supposed to dump back into the intake/air filter. Unfortunately with my K&N filters I do not have the inlets for these connections. Before taking a drill to the backing plate of my K&Ns I wanted to check with the forum members to see if you think I should do this. Here are some pictures to assist. Thanks

 

carbq1.jpg

carbq2.jpg

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I have seen two ways to deal with this. One way is to use long hoses and zip-tie (or otherwise fasten) them so they hang down below the frame rail. That way if they puke any fuel it will spill below the car and not on the hot exhaust manifold. The other way which I used to have on my car is to drill holes in the air filter backing plates and simply jam the hoses in - size the holes for a tight fit. Either way works fine.

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I have K&N filters to and I just run them to the side of the radiator right next to the radiator overflow hose. Dosent matter much where you stick it as long as its not going to get all over your engine, engine bay, exhaust, ect. and make a mess or start a fire.

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Heres a picture of what BARACU from the forums has done

attachment.php?attachmentid=316&d=1143930849

I wonder what kind of hose that is? also I wonder what the back side looks like.

 

Ben

Does anyone have any pictures of the back of BARACU's setup? I checked the hardware store and found a limited selection on nipple connectors. The only ones i found stick further out then then connector from the fuel bowls.

Thanks

 

Ben

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The original place to vent these lines was via metal tubes and a banjo bolt which put the venting down by where the stock cast iron manifold and headpipe joins.

In the USA they used lines to the air filter for evaporative emissions concerns. They WILL off-gas especially after a lift-throttle at high rpms as with the stock system you are pumping something like 7psi against the floats and have no consumption so it sinks the darned things, and you puke a little fuel up out of the jet---and in extreme cases of a long-rundown you can literally fill the float bowl to overflowing...

 

Indeed raw gas smell can come from up front. May want to make sure firewall gaskets are intact.

 

Keeping the stock air cleaner assembly on does have it's advantages! Keeps the smells down quite a bit!

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