flatlander442

Has anyone heard of a fuel restrictor in the return line on 66 442 4 bbl. carb. car? It is located at the tank of the car? What about 2 bbl carb or tri-power cars ? On a 4 bbl carb car without it would you run out of gas on full power run? Food for thought or over kill by a engineer?

L69 equipped

I have never heard of that although I am by no means an expert on the matter.

It has always been my understanding that all tri carb cars have different fuel pumps than the 4 bbl.

As far as running out of gas upon WOT , I seriously doubt that.

My tri-carb has never even hiccupped on WOT.


Dave

flatlander442

flatlander442

try this again!! I was reading my 66 assemble manual trying to figure out if the return line went on top or the bottom of main fuel line, and I saw a picture of the fuel line restrictor that is inside the return hose at the gas tank and it said 4 bbl carb only. So I dug out my old return line and tried to blow through it and it was plugged, cut it open and there it was! And it was plugged up. Its 1 inch long inlet hole is about 1/8 and outlet is pin hole size. Wonder how many people know that?!! Return line was useless!! does 1/4 inch return line go on top or below main fuel line on frame ?

L69 equipped

Dave


Interesting.

I am not around my assembly manual at the moment however; you would think that the line position would be addressed in it somewhere.

I would think that the return line would run below the inlet line, but that is pure speculation.

In any case, it sounds like you need to either replace that "filter" or discard it.

If you have a quality filter (to carb) which I am sure you do, I wouldn't even give a second thought eliminating it all together.


Dave

flatlander442

Dave, The restrictor is not a filter, I think it was meant to hold back the flow of gas returning to the tank so that the engine had enough fuel to function under all demands on it. But a good filter to keep the fuel clean is a must with the restrictor in the return line.I don't think it was a good idea if it plugged up and didn't let fuel return to the tank.I would like to know the reason for it Why not the tri-power or two bbl carb. I'm going to put tri-power on the car. My car was built the same time frame as the L69 cars. Not trying to build a fake one just like the looks of the tri-power. thanks Larry

L69 equipped

I would suggest sending a PM to Mike (see below) .

When it comes to 66 & 67 , (especially W30) , his knowledge base is second to none.

Dave



https://classicoldsmobile.com/forums...6-3x2+442.html

Chesrown 67 OAI

The purpose of the restrictor is to allow pressure bleed-off from the fuel pump. It relieves pressure sitting against the needle and seat in the carb and prevents unwanted fuel from pushing past needle and flooding the engine. It is done on the Q-jet models because of the notorious weakness of the needle and seat in that carb! I have learned something here too as i had never know about the restrictor even though i have owned several of these models. I do know that for racing purposed I have always restricted that return flow even further by putting a small hose clamp around the line right after it leves th fuel pump and tighten it till it stops the flow and then back it off just a bit to allow pressure relief. ( ovbiously this is done in conjunction with using an electric fuel pump along with the stock pump! As for which line goes on top? I should know but without going and looking at my car i cant tell you offhand -- I do know that there is a pic of it in one of the manuals because it is where i found the answer when i switched my cutlass to a "return-line" setup. Im sure you can find it in the tech pages at wildaboutcars.com. Go there and search for it

L69 equipped

Very informative. I never even thought about the needle and seat being vulnerable like that.

Thanks for sharing.


Dave