Fuel filter/separator Questions

[doubleyellow]

I want to use my original vapor separator. Car is for occasional cruising.

Questions:
1. Is using my original a good idea in the first place. Should I only use a new repro?
2. If I use my original, what is optimum way to clean it out internally without damage. Carb cleaner for example?
3. Does it actually do a fair job of filtration, or absolutely should always add a good fuel filter between the separator and the carb? Or not necessary?

Thanks

 

[Steve340]

I don't think those are a filter. Their main purpose was to eliminate vapor lock.

 

[floyd]

Agree, I believe there is a porous metal screen inside the vapor separator that would only prevent larger debris from getting to the carb. Not a true filter.

 

[Steve340]

Check it for rust and debris before you refit. Any crap/rust in it will go straight in to the carb or fuel tank.
Check the factory service manual for the true filter location.
I also think I read somewhere the cars fitted with those separators had a higher pressure fuel pump fitted to make up for the loss of pressure created by the return line to the tank.
Makes sense I suppose.
My car is supposed to have one but all good without it. No vapor lock issues.

 

[pschlosser]

As far as I know, the vapor separator does not really FILTER the fuel. There is only a screen inside, about the size of residential window screening. The screen on the fuel tank pickup is even finer, so it does most of the filtration.

To clean, you can soak in diesel fuel to soften any solids, and blow it out. You can follow with a degreaser, like Pine Sol, soak, rinse and blow it out.

If you find junk and debris coming out of it, and cannot easily clean it, I vote you replace it.

I believe I have heard some suggest these cars did NOT come with (replaceable) fuel filters from the factory. Where and when one is added is up to the owner.

Over the years, many owners seem to have removed the vapor separator, either out of ignorance or thinking it a fuel filter and replaced. Unless you want it on there to look factory, most only run them when vapor lock issues warrant it.

 

[cuda joe]

i would replace it who knows what junk and rust is in it .sometimes after running the carb float valve will leak a little allowing fuel to over flow the carb flooding the engine that separator bleads the pressure out of the fuel line so that won;t happen

 

[doubleyellow]

I finally pulled out the service manual but of course its very confusing.

In the “Maintenance” section is show a fuel filter, but not the vapor separator.

In the “Fuel” section is only shows the vapor separator.

My Dave Wise manual is not clear if there is a filter, or not.

Can anyone confirm if a 1970 440 4bbl AVS does, or does not, have a discrete fuel filter between the carb and vapor separator?

If the factory didn’t use a filter, looks like they relied on the vapor separator screen, but that seems risky on a high performance engine.

Thanks for the input

 

[cuda joe]

mine is a1971 383 car it did not come with a fuel separator the 440 and 426 cars did so i bought a 440 fuel line set up that cured the vapor lock and i put a filter between the separator and the carb

 

[doubleyellow]

Looks like the vapor separator does its job….

But my question is did the 1970 440 engine also come with a fuel filter after the vapor separator? From the factory. It’s confusing from the manuals and resto guides

 

[pschlosser]

Looks like the vapor separator does its job….

But my question is did the 1970 440 engine also come with a fuel filter after the vapor separator? From the factory. It’s confusing from the manuals and resto guides

I've heard from several sources the 440 HP engine with factory fuel separator did NOT come with fuel filter.

This is reenforced by the hard line on my 1970 440 HP car running from the vapor separator up the carburetor, which is one solid piece and bent in a way that seems OEM. The only place to add a fuel filter without cutting the hard line is just above the vapor separator.

But adding the filter there pushes the hard line upward and off the engine and intake a couple of inches.

The screen inside the tank at the pickup is a pretty fine screen, and does a good job filtering out sediment that may disrupt our our carburetors.

I read an article about the decline of Carter Carburetor Company in the 1980. It describes among other things, the popularization of fuel injected systems in the 1980s increased the need for better fuel filtration. And yea, fuel injection killed Carter Carburetor Corp.

 

[Steve340]

The fuel filter if it ever had one will be located in the engine bay for sure.
It would be on the inlet side of the fuel pump as I assume the vapor separator would have been the only component on the outlet side of the pump.
Any evidence like a shortened fuel line before the pump or any other signs? Is there any room for it and 2 short rubber connectors?

 

[eboy]

OK. As is OER description of the part, it is a fuel filter and vapor separator in one unit, as was the factory assy. No need for an "add on".

 

[Steve340]

I would not worry to much about a filter. From what I have experienced they are useless at keeping rusty crap out of the carb.
They filter out the dogs and cats but f*** all else.

 

[doubleyellow]

Thanks for all the input !

 

[Challenger RTA]

Here's a start. to figure out what you want to do.
The ECS systemm had nothing to do with the vapor separator.
The vapor separator/filter was used on all '70 440 4bbl - 440 6bbl - HEMI cars.

The return line from the vapor separator goes to the sending unit with or without ECS.
the vapor separator goes into the tank

The ESC has no provision for what you want to do. It returns vapor from what I understand.
I think this is what you have to do.

 

[pschlosser]

It would be on the inlet side of the fuel pump as I assume the vapor separator would have been the only component on the outlet side of the pump.

Most "after-market" fuel filters (be they OEM or owner-added) seem to be found in areas convenient for the driver/DIY-mechanic, which is AFTER the fuel pump, on top of the engine, where one can easily change the filter. The next best location, is in FRONT of the engine, above the fuel pump. Anywhere else, one must go to their knees (without a lift) and crawl.

The OEM screen on the fuel pickup inlet is rather fine. It filters sand particles (100 microns) and thicker dust particles (10 microns).

Any fine sediment (when present) within the fuel flow has shown to have little impact on the performance of these diaphragm (mechanical OEM) fuel pumps. I am unaware of ANY (vintage pre-fuel-injection) article, or news report, anywhere, to the contrary.

Add a fuel filter if you want. But it's not critical for most drivers of these vintage carbureted engines. Only those living in the harshest of dust environs, need lose sleep over the "fuel filter."

Back in the 1970s, perhaps the metal screen (within the fuel separator) was considered a "filter" but the screen was magnitudes larger than the finer one at the fuel pickup inside the tank.