My Fuel Filter / Fuel Line Solution

Padraig

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I finally got around to fitting proper fuel filters to my '78 650E.

My initial attempts were foiled by the stiffness of the generic 1/2" OD - 1/4" ID fuel hose from the auto parts store. It was too rigid to make the necessary bends and two thick to fit between the carb body and frame. I had recently had similar trouble trying to route 1/2" OD line on a snowblower, and ended up buying a box of Briggs and Stratton fuel line. It's 7/16" OD and 1/4" ID. Doesn't seem like it would make much of a difference, but it certainly does. It's considerably more flexible, and just small enough to get between the carb body and frame. There is so little distance between the petcock outlets and the carb inlets that fitting a filter in between seemed futile.

As you can see in the pics, I routed the line around the airboxes to avoid kinking, and wrapped the line with mesh wire loom to protect it from rubbing. It was very disconcerting at first that the fuel filters did not appear to fill up (freakin' physics), but the carbs get all the fuel they need as long as all the line is below the tank. The clamps I used are the Oetiker type (I buy them by the 100s), and are properly crimped to the petcock and carb, but not to the filter. They fit snuggly enough on the filter without crimping and,that way, disconnecting the filter for tank removal is not a problem. Just put the clamp where it belongs on the hose first, spray some silicone lube in the hose end and fit the hose to the filter. Also, you can't see this in the pictures but the line from the left side petcock ends up on the right side carburator and visa-versa. That keeps the fuel lines straighter.

The parts I used: Briggs & Stratton 395051R 25-Foot Fuel Line (about 5' worth); AutoZone Duralast Fuel Filter FF2314DL; Oetiker clamps (11.3mm open diameter); generic mesh wire loom.

Hope someone finds this useful!
 

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I used that type of fuel filter exactly once. On a rally ride my right side carbie started puking fuel at stop[s till I gave it a few taps. When I got home I opened the carb and found bits of clear plastic and debris in the float bowl. When I inspected the fuel filter I found that the paper element had broken loose from the plastic shell. 'Nuff said.
 
I used that type of fuel filter exactly once. On a rally ride my right side carbie started puking fuel at stop[s till I gave it a few taps. When I got home I opened the carb and found bits of clear plastic and debris in the float bowl. When I inspected the fuel filter I found that the paper element had broken loose from the plastic shell. 'Nuff said.
Thanks for sharing that. I'm trying to keep from pulling my carbs apart, LOL. It doesn't help that the filter are subjected to some minor vibration. :)

I'll consider swapping them for the cone type with the bronze elements.
 
I run a line from a single petcock to a single cone shaped fabric element filter, then to a T connector, then to the carbies. Filtration isn't as fine as the paper element filter, but it doesn't have to be. I've used bronze element filters as well. Never had one fail, but all of the cone filters soften after awhile with 10% ethanol fuel. When that happens I change them out.
 
Thank you so much! I definitely want something that will last, so I don't have to mess with my carbs again. The price seems reasonable for the protection and longevity. They won't be getting too much heat, so I don't think the same issues the aircraft are having with them will be a problem. I'm more concerned that that stay intact being subject to the alcohol in our gasoline. Thanks again, all, for the detailed responses!
 
My BS38’s with filters and 1/4” ID Tygon fuel line. Fits well without kinking on a ‘79 Special. I used the same filters and lines on the ‘76 but found the lines were better routed side to side. By this I mean the left petcock feeds the right carb and right to left carb. I shut both off everytime so it doesn’t matter to me that they’re crossed.
Last year bought a box each (1/4 & 3/16) of very nice quality double wire hose clamps. Really nice fit. Far superior to the cheap single wire ones I bought from regular sources.

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