Ford Lehman air filter replacement

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Ford Lehman air filter replacement

Postby jmcj » Mon Sep 16, 2019 11:00 am

I have long thought the foam air filter arrangement on the Ford Lehman could/should be improved upon. Has anyone undertaken this as a project? Is there an aftermarket product (like K&N filters) which would be suitable? How would crankcase pressure be dealt with?

Photos and descriptions of the process would really be appreciated.
Jim McJannet
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Re: Ford Lehman air filter replacement

Postby GB42-267 » Mon Sep 16, 2019 1:01 pm

This is a link to an old posting:
http://www.grandbanksowners.com/gbb/viewtopic.php?f=20&t=19571&p=110006&hilit=filter#p110006
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Re: Ford Lehman air filter replacement

Postby Chesapeake » Mon Sep 16, 2019 4:07 pm

K&N RC-4570 is a good fit. 2-7/8" ID, and it's offset so you can vent the crank case into the top of it if you want. I like Bjorn's idea for venting though!
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Re: Ford Lehman air filter replacement

Postby jmcj » Tue Sep 17, 2019 12:44 pm

Thank you for the responses. I remember your post Bjorn but I guess am a bit apprehensive about drilling into the manifold. I will think about it however and will look at the K&N filter option. My guru also suggests trying a Brackett Aero filter.
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Re: Ford Lehman air filter replacement

Postby Sandpiper » Tue Sep 17, 2019 5:04 pm

On Sandpiper I used a Walker Airsep unit. Easy to install and much better than the original Ford/Lehman filter. Vapor from the valve cover is also directed into the filter assembly. It was about a 15 minute job to remove and replace air filters.
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Re: Ford Lehman air filter replacement

Postby soo-valley » Wed Nov 20, 2019 12:01 pm

Curious why the decision to upgrade on the foam filter.
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Re: Ford Lehman air filter replacement

Postby jmcj » Thu Nov 21, 2019 12:18 pm

The decision to change was based on what I understand to be slightly elevated Si (generally considered to be dirt although there can be other reasons) levels in the annual oil analysis. They are generally in the 4-6 ppm range although there have been spikes. Although the analysis report still notes these as being acceptable levels I would like to lower them. Annual engine hours (Hobbs meter) are around 250.

I would be interested to hear what values other Lehman owners are receiving. I'm using the Finning lab.
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Re: Ford Lehman air filter replacement

Postby bpbyrne » Tue Nov 26, 2019 7:23 pm

its on my list to find a couple of appropriate diameter k&ns to stick on thete..i too find the standard filter a bit crude and have had geeat success with high flow k&ns in other applications
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