help with factory carb

[Grey_Matter]

i just picked up a factory carb and am having an issue with the fuel lines.

the weber i took off only has one fuel line, but my stock carb has two. where do i run the second line to?

 

also, the factory carb doesn't have a vacuum port for the distributor advance, can i run it to the air cleaner or one of the vacuum lines on the intake manifold?

 

pics:

overview to show my routing:

 

the fuel line in question:

 

and can i use these for the vacuum advance?:

[MicroMachinery]

The 2nd fuel line is the fuel return. There should actually be 2 lines that come from your tank. An "in", and an "out", if you will. If you don't have a return line to the tank, I'd say just plug the 2nd line; my 521 only has one line coming from the tank, and it does just fine.

As far as the advance goes, there should be a port for the advance on the "engine side" of the carb. I'm curious as to why there isn't one.. I'm a little leery of using carbs that weren't designed for the specific application. If I were going to put on a different-than-stock carb, I'd go with a weber or something like that.

[Grey_Matter]

The 2nd fuel line is the fuel return. There should actually be 2 lines that come from your tank. An "in", and an "out", if you will. If you don't have a return line to the tank, I'd say just plug the 2nd line; my 521 only has one line coming from the tank, and it does just fine.

As far as the advance goes, there should be a port for the advance on the "engine side" of the carb. I'm curious as to why there isn't one.. I'm a little leery of using carbs that weren't designed for the specific application. If I were going to put on a different-than-stock carb, I'd go with a weber or something like that.

 

that's the funny thing, this is a stock/factory carb off of an L16 from the same model year (both are 1973, but mine is an early and his is a late)

i'll look some more and see if i cant find a second fuel line for the return

[Grey_Matter]

blocking off the extra line worked. i crawled under the truck and there is definitely only one fuel line and two vent lines.

 

i just got done starting and adjusting the carb, it idles nice and revs without any hesitation, although my timing is definitely off a little, time to go buy a timing light :)

[datsunaholic]

That's not a stock 620 carb, does it even have an electric choke? Looks like a Chevy LUV carb. They're both DCH-340s. Or maybe a 510/521 Cali smog edition? But I'd suspect LUV, just by the fuel inlet direction.

 

No, you can't use any of those arrowed vacuum lines for vacuum advance. Must use ported vacuum off the primary.

[Grey_Matter]

That's not a stock 620 carb, does it even have an electric choke? Looks like a Chevy LUV carb. They're both DCH-340s. Or maybe a 510/521 Cali smog edition? But I'd suspect LUV, just by the fuel inlet direction.

 

No, you can't use any of those arrowed vacuum lines for vacuum advance. Must use ported vacuum off the primary.

 

its not from a 620, but it is from an L16b. it was pulled from a 510

and i used the vacuum line from the far left arrow and it seems to be advancing like it should.

like i said earlier it revs like a champ with absolutely no hesitation, i'll know for sure if the advance is working properly once i get the tranny in and drive it and listen for the pinging