Fitting adapters for an early model mechanical fuel pump?

ArVeeNiner · #1 03-26-2009, 10:12 PM

OK, between screwing up my canopy frame and carb, I'm also trying to plumb my mechanical fuel pump. I've been trying to get to the bottom of this for a while and have made no headway.

I have an "early model" mechanical fuel pump on my O-320. Here is link: http://www.aeroaccessories.com/fuelpumps/lycoming.html

So I ordered the KB-090-T Tee fitting and KB-000 straight fitting from Van's per the "Carburated Fuel System" drawing. Neither fit.

Then, I thought the fuel pump had galled threads and I posted here. Somebody told me to use the AN833-6 90 degree steel fitting and AN924-6 jam nut which seems like a good idea but I won't be able to T it off for fuel pressure like on the Van's drawing.

Wanting to eliminate the fuel pump, I had another one sent. Still, no go.

I called Van's and they said theirs worked just fine in the fuel pumps in their shop.

Finally, I ordered the 07-00783 T fitting and 07-00780 straight fitting from Spruce. Still, no go.

So tonight I dug around some more online and I think I may be on to something. The early model pump like I have take a straight thread (this was told to me in an earlier post) and there appears to be an adapter out there. It appears that Sac Sky Ranch might have adapters...at $30 a pop!

Soooooooo, am I the only one out there with an early model fuel pump? How do I attach fuel lines to this pump???

Tomorrow I will call Aero Accessories, the people who rebuilt the pump. I hope they know.

Now, I have to get back to packing up all the stuff that doesn't work!

mahlon_r · #2 03-27-2009, 06:04 AM

Way back in the day when my hair was a lot longer and darker, there was a pump that had 1/4 NPT tapered pipe inlet and outlet ports. That updated to a pump that took straight threads and an o ring. When you used the later, you installed a bushing into the pump to convert from the straight thread to the tapered NPT. Later, they started using a fitting that eliminated the adapter and that had an integral oring and jam nut. So to answer your query, I think you have one of the oldest style pumps with the tapered NPT ports. If you want to use Vans fittings you will need to get a later style pump with different style ports. Or not use Vans fittings and install regular AN fittings in the pump and use a t fitting and two hoes in the outlet line to the carb and use the T part of the t fitting for fuel pressure. Or build a T at the carb inlet to give you a fuel pressure port.
I can't believe that I am old enough to remember all this **** from the late 60's and early 70's! How you got a hold of one of those pumps, for you RV, is beyond me. They are treasured items, at one time before people overhauled fuel pumps, because in certain installations all of the later style pumps and fittings interfered with the engine mount. I think the Comanche with a 360 was one of them. The choice at fuel pump replacement, was get an old style pump or get a new engine mount that fit the new style fuel pumps and fittings!
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

ArVeeNiner · #3 03-27-2009, 08:21 AM

Yea, I thought they looked tapered to me. I'll look through the Aircraft Spruce catalog to see if I can figure out which fittings to order.

My engine was built in 1963 and it had a high pressure pump on it that the guy who sold it to me kept. Then he gave me a junk pump to use as a core so I just ordered the one that he gave me.

Will a newer pump fit in the same hole on the accessory case? It might be easier to go with the newer pump. I'll check my engine mount but I think there is plenty of room for a newer model pump. In fact there has to be since I think there are many RVs with the new pumps.

mahlon_r · #4 03-27-2009, 08:38 AM

Yes, the new style pump will fit the same hole on the engine. Only the pump was different not the mounting/parting surface on the engine.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

ArVeeNiner · #5 03-27-2009, 09:48 AM

I found Lycoming Service Letter L218 which can be found here: http://www.aeromanagement.com.au/navajo/VSP%2075.PDF

It shows adapters to go from late pump straight threads to the tapered threads on the hose that remains in the airplane. I guess these are required when swapping an old style pump for new style and you don't want to change your lines and fittings.

I called Aero Accessories who supplies the Tempest rebuilt carbs for Aircraft Spruce and they told me that the 40295 pump is short like the old style pump but has straight 9/16-18 threads like the new style pumps. I think any height pump would work for me because I don't think there is a chance that the taller pump would interfere with anything. I'm not at home to look at my engine to 100% verify this but I'm 99% sure there won't be any interference.

Anyway, they are sending me the 40295 pump and I am sending them the original 40174 pump that I got from Aircraft Spruce AND the replacement 40174 pump that I got from Aero Accessories.

I have to say, I'm impressed with Aero Accessories. They are sending me these pumps at no charge, free shipping, and entirely based on my phone calls to them. I'm just a voice on the phone. They never asked for any proof of purchase or anything that actually proves that I bought this pump in the first place. Man, talk about old school. They are great! They even asked me if I needed it overnighted!!! I told them cheap shipping is fine.

You know, you run into this sort of thing in the airplane world (especially in the RV world) all the time and it's wonderful. What a bunch of great people out there! I've purchased and sold a few things to RVers and it's almost always the same thing, the check and the package cross in the mail. We expect that we will pay when we say we will pay and that packages will be sent when we're told they would be sent. I really have to readjust when I deal with the real world outside of the airplane world! Of course, sometimes you get a pilot/investor (Marcus Schrenker) who tries to fake his own death by jumping out of his plane over Alabama.

You know, I don't know what the best thing is about RVs...the planes or the people!!