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I saw some posts either here or on the samba about plumbing external oil stuff. Most recommended AN-8 or AN-10 fittings and hose and offered various theories about how the size of tubing affected the function. 

I asked the tech at CB about this with not much of an answer. My query: both the in/out from my MaxiFlow filter and the filter body are 1/4".  Is there any logical reason based on real world flow dynamics that I should not use an AN-6 fittings and hose, keeping in mind that my primary focus is maintaining oil pressure?



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Maxi-flow filter pump? Personally, I wouldn't use one. The passages have too many sharp turns which lowers pressure. Are they 1/4" pipe thread or physically 1/4" diameter? If the passages measure 1/4" I.D. then I'm right that the passages are too small.

I recommend full-flowing your case, and using a pump cover with an out fitting, such as a Berg cast iron pressure-relief cover. 

1/4" pipe thread has an outside diameter of just over 1/2", about 3/8" inside diameter of fittings, which is 50% larger than 1/4" lines. AN lines are rated in 1/16", so AN-6 is 6/16 or 3/8, AN-8 is 1/2", AN-10 is 5/8".

AN-3 is usually used for brake lines, AN-4 and 6 are used for fuel, and AN-8 and 10 are usually used for oil.

If your cooler is near the engine, I'd use AN-8(what I did on my Spyder). If you have a front-mounted cooler then I'd use AN-10 to alleviate the pressure loss.

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