1/2 inch fuel lines,, are they a good thing? 1948 C-170

[edgar]

I am restoring a 1948 cessna 170 and I have to replace all the fuel lines ,,
bad bends etc in the old ones. This plane had the fuel pump removed years ago, (like most 1948 C-170's) before I bought it.. I would like to go to a electric boost pump instead of a engine driven one, Also In a few years I would like to up grade the engine to a franklin or 6 cyc Cont.... Should I go ahead and install 1/2 inch fuel lines now instead of stock smaller ones .. ( Do you have to have bigger fuel lines for bigger engine installations?? do the big engine conversions require a fuel pump???) Where I do not have to do it latter..?
I would like to now, will I have to change the fuel selector, and gasolater ?And what else ?,
For the 1/2 inch fuel lines? What kind of electric fuel pump systems are people running on 1948 c-170"s . *** Any Ideals????

Thanks

Edgar

[GAHorn]

If you make any changes.....any at all...to the orginal fuel system you will have to obtain FAA approval in some form....either an approved Form 337 with block 3 filled out by the FSDO (field approval) or an STC. The fuel pump system, as depicted in the original Illustrated Parts Catalog (IPC) must be intact. This fuel pump served the purpose of ensuring correct delivery of fuel with the original fuel system. (Later systems cured the delivery problem with a re-design.)
Any other changes you are suggesting must also be approved by the engine installation STC/Field Approval you are contemplating. It is probably not a good idea to "plan ahead" for some increased fuel line sizes unless you know the STC you are planning on purchasing will require/approve them. You will not only be increasing your work load and expense, you will not have an approved/airworthy airplane until the entire STC is performed otherwise. (In other words, without the entire modification performed at once, then you'll be duplicating work, and complicating approval processes.)

[zero.one.victor]

First of all,to the best of my knowledge the engine-driven fuel pump is required equipment on the 1948 (ragwing) 170. This is regardless of whether it has the original C-145 engine or a later O-300 A,B,D,or whatever. The routing of the fuel lines (down the front doorpost,as opposed to down the rear downposts as on the A & B models) creates a high point in the fuel lines that could cause fuel starvation should the fuel line "siphon" action be interupted. The pump should prevent this from occurring.
Assn member Duane Shockey of calif. had an electric fuel pump field-approved for his ragwing. I think Assn HQ has a copy of his 337. Assn member Thomas Arsenault of Minn. wrote an article about installing the standard fuel pump & associated stuff on his pump-less ragwing in the #1 & #2/1999 issues of the 170 news.
I thought about getting rid of the mechanical pump & installing an electric pump set-up at the time of my engine overhaul 2 years ago,but my mechanic convinced me that it wouldn't be worth the trouble it would take to get it field approved. The electric pump on a friends Cessna 150/150 conversion is what got me thinking about this--one line from gascolator to pump,and another from pump to carb. No checkvalve & tee for bypass of the pump,and no lines going all the way up to the front of the engine where the pump is,and then back down to the carb. The electric pump in question has a built-in bypass circuit,and is only switched on for takeoff and landing.
Secondly,as far as I know,there is no engine upgrade STC'd for the ragwing model. I have seen a ragwing with a Lycoming O-340,and I read about one in The 170 Book that had a Continental IO-360,but I believe they were both field approvals. I understand that field approvals for this type of change are hard to get these days.
I would talk to whoever sells the engine conversion(s) you're interested in with regards to changing the fuel line size. They might be willing to work with you on adding the ragwing to their STC. Harry Dellicker of DelAir told me that the smaller lines were the reason why the ragwing is not included on his Lycoming O-360 STC.
Lycoming O-360: DelAir 559-784-9440 *
Continental IO-360: XP Mods 800-819-9270
Franklin 220: Franklin 970-224-4404 *
(* advertises in the 170 News)

Eric