ramjet 350 fuel pressure and return line clarification

[56hotrodred]

I am looking for a little information on the fuel lines for the gm ramjet 350.

Which side is pressure/inlet and which side is return?

It looks like the left side fuel rail is -AN6 male nipple and requires a -AN6 female thread to connect and the right side is 3/8NPT which I don't know if it is male or female!!!

I am assuming that the pressure/inlet side gets the inline fuel filter and that it is the larger right side!!!

I do have the in tank fuel pump but am not at home to look at it!!!

Thanks much in advance.

[_Ogre]

unless you bought the ramjet used, you should have the manual that comes with the motor, everything is very clear in there
passenger side is in, drivers side has the pressure regulator in it
run 3/8'' fuel line to both sides from the tank/pump with flex line where you come off the frame
should be ~45psi at the test port in the fuel rail

[_Ogre]

i mounted a typical gm efi fuel filter on the frame
i believe this used a bubble flare on both sides

[_Ogre]

installing a ramjet 350 is the best mod i did to truk
8 yrs of ''same ol same ol'' turn the key and go, never adjust anything, same plugs after 33k, cleaned the air filter and 5 to 7k between oil changes

[56hotrodred]

I don't have the engine yet but have downloaded and printed the "specifications."

It is not so clear!

Here is all it says about the fuel lines; and I quote...

"The fuel pressure regulator is mounted on the left rear rail and uses a male -6AN nipple on the bottom. This is the fuel return line that will be necessary to adapt to your application. The right fuel rail has a 3/8" NPT hole that is used for the fuel inlet. You will need to determine what will be needed to adapt the inlet fitting to your application."

So I have bought -6AN PTFE fuel line to hook up to the left rear rail and use as the return line. It runs back to my new fuel tank.

I also bought an adapter to hook up to the 3/8th NPT hole on the right fuel rail to change it to and hook up to an -8AN PTFE fuel line and in addition bought an inline fuel filter with fittings to hook it up to the -8AN fuel line.

Does that make sense?

Many applications that I have looked at are using the same size fuel lines on both sides, others are using a different side for inlet and return, like I am.

Does the -8AN fuel inlet with a 10 micron in-line filter and -6AN fuel return line sound right?

Today I just bought a bunch of PTFE fittings but I have had the -6AN and -8AN PTFE fuel line for a while. Nothing has been cut or installed yet so lots of time to change both to -6AN if that is the recommended way to go.

I also today just ordered the in-line fuel filter with -8AN fittings on each end but could easily send it back and change for one with -6AN fittings!

To be truthful I am not sure where I saw or arrived at needing the two different fuel line sizes for my application (i.e. engine) but have seen it used in others. maybe higher horsepower engines.

Any help would be appreciated because as said I could easily send back/exchange the filter and order some more -6AN line.

I hope this is clear.

Thanks in a advance.

[_Ogre]

the full manual is a lot better than the specification, but i see where your coming from
we pulled the sbc in 58 truk out and installed it in my sons 68 elco
the 3 yr warranty was 3 years over by the time i got my truk running again

AN fittings are sized by sixteenths of an inch. 6AN is 6/16ths or 3/8''
no reason to use half inch line unless you already bought everything
i used a 3/8 npt to 6an 90 degree fitting to go into the fuel rail, a straight fitting will hit the dist
the fuel regulator has 6an out the bottom

the mefi controller and coil are mounted on the back of the heads
that location doesn't work on tf trucks, i modified the brackets to where you see them
the distributor has a big plug coming out the back, modified the firewall to accept the plug
relocated the knock sensor from the pass side to above the oil filter due to interference with block hugger headers
drilled the end of the air filter out using a die grinder for the AIT sensor

lots of pics in my build thread, takes a little work to see them but worth the effort

[56hotrodred]

Ya I do have everything, or at least will by tomorrow when the brown-truck shows up here at my little place in Arizona. Tomorrow I will have the in-line fuel filter and all AN fittings, with a few extras.

I am glad to hear that I don't have to send anything back! As I said I really can't remember how I derived at needing -8AN on the inlet side but it sounds like it is not going to hurt anything.

You have been extremely helpful throughout this whole process and I thank you for that.

I leave here in about 2 weeks and hope to be picking up my engine shortly after arriving at home - so early April!

Because I am in a rural location in Alberta it is way easier to bring all these little parts up with me. Even with our Canadian dollar being so low it still make economic sense to buy this stuff down here - thus my millions of questions!!!

[_Ogre]

look around at the prices as it varies greatly
the motor is manufactured by a roush subsidiary in brighton mi about 25 miles from me
buying it locally would have cost me more in taxes than it did to buy it out of state and $350 shipping
i bought my ramjet from a chevy dealership in chicago

[_Ogre]

the ramjet 350 came as you see it here
spark plugs, oil filter, valve covers, air filter and distributor: all installed