I'm putting my 71 SS back together, and will be running a 402 w/a holley 650, but not for ever. When the body work is done, I plan to run a 565. Is there any harm in running a 1/2" fuel line now?

Nope...;)

Run a 1/2" return line while you are doing it or at least a 3/8".

Just use an adapter to downsize it at the regulator if you are using a smaller regulator temporarly.

The ONLY reason, and I personally don't think it should matter, is that it's not "technically" correct if you are trying for a 100 point restoration.

Otherwise, go 1/2 while you are at it.

The ONLY reason, and I personally don't think it should matter, is that it's not "technically" correct if you are trying for a 100 point restoration.

Otherwise, go 1/2 while you are at it.


My silver vein metallic powder coat on the frame and Global West suspension blow that to pieces anyway. Half inch it is guys. Thanks for the advice!

Seth, what HP level will you be reaching for with the 565? If it will be above 750 HP, then I'd forget the 1/2" fuel line, and choose a 5/8" instead (that be a -10AN). That's what I've decided to do with my 632 in my 1970. From everything I've read, a 1/2" line (-8AN) is good up to 750 HP. Unless you're one of those guys who will never race it nor hit full throttle, but will only take it to shows and let it just sit there and look pretty. In that case, it doesn't really matter what size line you use I guess.

One more question. What do I do for a sending unit? Half in line doesn't make much sense if the entire supply is corked at the 3/8" sending unit.

I welded two outlets at the bottom of my tank, one in each corner and two lines to two large fuel filters, then into two high pressure holley pumps and then into a stainless 1/2 inch fuel line up to a good holley regulator where it feeds the carb with 6 pounds of fuel pressure.
I do NOT run a return line and so far I have never had a problem.
I have the same setup on my nitrous 355 mustang.

Seth, what HP level will you be reaching for with the 565? If it will be above 750 HP, then I'd forget the 1/2" fuel line, and choose a 5/8" instead (that be a -10AN).

I would second this. I would run 5/8" if I planed to install a 565 because 1/2" line would more than likely not feed that beast.

One more question. What do I do for a sending unit? Half in line doesn't make much sense if the entire supply is corked at the 3/8" sending unit.


The 3/8 sending unit has to be revised for a high HP application. You have options to choose from or invent some. A few suggestions are:

1. If you go 1/2" supply with a return. Modify a 1/2 tube on side the 3/8 and use the 3/8 for a return line.
http://www.69boo307.com/images/halfinchpickup.JPG


2. If you go 5/8", sump the tank. Use the fuel sending unit for gauge purpose only and put a bulkhead fitting in top of the tank for the return line.
http://www.jegs.com/images/photos/500/550/550-40757.jpg

I like the sump idea much better. Because I've heard some guys say that when they used the OE tank set-up by drawing fuel from the tank through the top as in the first pic above, that they experienced problems with their electric fuel pumps losing prime. And I'm inclined to believe those stories since most of the manufactures of electric fuel pumps state clearly in their installation instructions that the pump needs to be gravity fed. As you probably already know, electric fuel pumps are great for pushing fuel (and thereby eliminating or greatly reducing any chances of vapor Lock) but they aren't so great for drawing the fuel. Particularly drawing it uphill against gravity.

So I think that the sump is always a better idea (which is one of the reasons that I chose a fuel cell) since it will allow the electric pump (if that's what you're using) to be gravity fed. And according to the pump manufactures, that's very important.

Yep AN 10 or 5/8 OD alum fuel line ...... I have not had any problems with replacing the factory pickup withthe 5/8 line in stock location much like the picture in post above and I dont even use an electric pump

Yep AN 10 or 5/8 OD alum fuel line ...... I have not had any problems with replacing the factory pickup withthe 5/8 line in stock location much like the picture in post above and I dont even use an electric pump That's probably why you don't have any problems then. Mechanical fuel pumps are much better at drawing the fuel than electric pumps are. Mechanical fuel pumps don't need to be gravity fed like electric pumps do. But electric pumps will blow away most mechanical pumps for pushing high volumes of fuel forward. And mechanical fuel pumps make your system more prone to vapor lock when things get warm, since they're drawing the fuel rather than pushing it like electric pumps do. So there are trade-offs and pros and cons.

Good point re electric pump re not drawing as well so yes I agree sump for electrics ...... I'm using Howard Stewarts mechanical "Race Pump" so no fuel delivery issues so far

http://www.69boo307.com/images/halfinchpickup.JPG


Hey that looks really familiar :D

Hey that looks really familiar :D


Yours was prettier than mine :)

http://static.racingjunk.com/1/ui/1/1/8173072373913.jpg