340 Dart - Fuel Filter location

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Big Guy

Big Guy

1970 Dodge Dart Swinger
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I would like to know where is the best location to install a fuel filter on my 1970 Dart Swinger 340? My neighbour who has a 69 - 340 tells me that it should be installed just before the mechanical fuel pump between pump and fuel tank. From most pictures that I have seen, it shows a filter located just before the carb after fuel pump. What is the proper location or should I install a filter in both locations?
 
Chrysler did it both ways through the years. It's something that's just not very critical.
 
I remember them between the fuel pump and the carborater. 65'
 
If you're running the standard 2 nipple filter, it can go in either location. If you're running the 3 nipple filter with a return line, it MUST go after the pump.
 
I've never seen an OEM Mopar with a filter before the pump. Also if you do that, you need a low restriction high flow filter because of pressure (vacuum) drop. Most parts guys don't even know what they are. Most are not a filter so much as just a strainer.
 
67Dart273 said:
I've never seen an OEM Mopar with a filter before the pump. Also if you do that, you need a low restriction high flow filter because of pressure (vacuum) drop. Most parts guys don't even know what they are. Most are not a filter so much as just a strainer.
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Lots of 70s and 80s trucks had them there.
 
I agree with putting them after the fuel pump to avoid the extra restriction from the gravity fed side of the fuel pump...

The restriction of the filter is not as detrimental after the fuel pump where there is more pressure to push the fuel through...
 
krazykuda said:
I agree with putting them after the fuel pump to avoid the extra restriction from the gravity fed side of the fuel pump...

The restriction of the filter is not as detrimental after the fuel pump where there is more pressure to push the fuel through...
Click to expand...
The pump inlet is not gravity fed. It's suction fed. You can measure it on a vacuum gauge.
 
The filter did once lay horizontally on top of the intake just before the carburetor. When they changed to the unleaded lower octane fuel (1973 I think), the filter moved to vertical down low, right after the pump. Less fuel percolation. If you go this route you'll need the later model pump due to its outlet changing position and the later fuel lines also.
This change eliminated the fuel delivery issues of my 67 273.
I highly recommend following some OEM engineers' examples (pre 1980).
 
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Putting it after the pump is typical. In case of tank debris or fuel pump coming apart. It protects from both. The pump coming apart is rare but does happen.

Putting a filter before the pump protects the pump from tank junk. But may cause other issues. A screen filter is best for that location.
 
IMO- All 340's had the filter after the pump and before the carb. It was laid at an angle above the intake manifold (exit end up slightly). If you decide to also put one before the pump make sure that it's easy to get to. You will be replacing the rubber hose ends due to cracking which is my experience and if you're not mindful of this it's a fire waiting to happen. This is all considering that you're not using AN fittings to connect everything.
 
Theres a recent thread on here orig owner states his filter from factory was before the pump.
Cant remember which car he has.
 
Side add: people are not all aware about this but with some filters (barrel with in and out port factory style) not all come with those short section of hose able to handle ethanol fuels. I typically use from my local Napa Gates Green stripe fuel hose.
It handles the ethanol fuels long term. Cheaper fuel hose split in a short time.
 
Out of the 1970 Factory Service manual
Big Guy said:
I would like to know where is the best location to install a fuel filter on my 1970 Dart Swinger 340? My neighbour who has a 69 - 340 tells me that it should be installed just before the mechanical fuel pump between pump and fuel tank. From most pictures that I have seen, it shows a filter located just before the carb after fuel pump. What is the proper location or should I install a filter in both locations?
Click to expand...

20230710_081352.jpg
 
Beginning in 1963 Chrysler mounted fuel filters so the outlet would let the vapor out, minimizing vapor lock.
Carburetion and Performance Diagnosis (Session 188) from the Master Technician's Service Conference

1970 basically same position shown in the Dodge Service Manual
1688994932531.png


There is also a 'sock' filter on the pickup tube in the tank.
1688995031927.png



Moving the filter before pump was a measure when all else failed to resolve customer complaints about delay in starting in severe hot conditions
As explained in the 1972 bulletin, its a tradeoff.

Additionally on an engine with potentially high fuel flow (ie high rpm full throttle racing) any restriction before the pump may be a strain. Pumps push better than they draw.

make sure there is summer fuel in the system before going to those sort of measures.
www.tapatalk.com

racingfuelsystems-What to do about Winter Fuel in hot temperatures?

x2 That's a fair bit of work, good stuff. I hope you took advantage of the grill to have some steaks.
www.tapatalk.com www.tapatalk.com
 
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As other have stated above, it looks like a Chrysler switched the location of the pump around the time emissions/drive ability concerns took hold. My 75, which has been in my family since new, has the filter before the pump.
 
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