I love my Weber 38 DGES. Here's my 38 DGES install:

[nerdistmonk]

The problem with a return line on a carb system that has a low pressure pump (4 psi or lower) is your not lowering pressure your lowering volume, everyone keeps overlooking that, volume is critical, your vehicle will run with any pressure as long as it isnt so high as to damage the needle valve, its volume that keeps it alive, your redirecting fuel that needs to be ready for the carb, whats the point of a fuel pump that just cycles the fuel constantly? The reason weber documents a maximum pressure is because they never intended for you to have a return spout, if they did it would be installed on the carb itself opposite the input.

 

You need return lines on EFI systems due to the tremendous pressure of an efi system (22+ psi), also since EFI is dynamic, it can adjust its fuel consumption on the fly and as such may need to return fuel back to the tank. It doesnt return fuel to keep it cold, this isnt a beverage fridge, its an engine.

 

But on a low pressure system a return line is unwarranted, if your having vapor lock issues the return line is just a band-aid a cover, it would be better for you to find the root cause of the vapor lock (usually heat, and a vac vent on the fuel bowl would work wonders i would suspect), because if you manage to starve the engine of fuel (and yes you can do it without knowing, unless you pull the spark plugs every other week and look/smell), starving the engine of fuel = lean = hot combustion chamber and hot intake manifold = hole in piston if drove like that for a long time. Its just as bad as over-advanced timing (which i didnt know caused the same thing till about 5 days ago)

 

Anyways i got no return on mine, cant tell one bit of difference, other than it certainly starts faster than before.

 

All of the above is my opinion, if you dont agree with any of it thats fine. No hard feelings.

 

Off to bed, g'night and take care

[banzai510(hainz)]

remember when the pump fills the carb it goes lim the diapramen is not working or fully working/wearing it out

[nerdistmonk]

i would say any real damage would occur if you power up the pump and the engine isnt running (my truck you never ever turn the ignition on and leave it, since it powers up the coils and pump)

 

As for whether it hurts them in the long run, your right it will mostly cause some wear but thats why i am going to buy a rotary vane pump for the thing soon (along with the 38 weber ive been discussing in another thread), no diaphragm on that beast (internal pressure regulation)

[pl521sss]

Very nice write up!!

That intake manifold, is it any better than those non smog types?

[banzai510(hainz)]

on the 38/38 for dieseiling I just push the pedal down to open the butterflys up and creates a vacuum loss

[KlassicMotion]

on the 38/38 for dieseiling I just push the pedal down to open the butterflys up and creates a vacuum loss

 

Interesting.  I've never heard of that.  Makes sense though.  Do you do it just after you turn the key?

[banzai510(hainz)]

its a learnd thing just try it.

Rememer the acell pump is going to dump some gas so as it revs up then hit the key

[Silky_Johnson]

KlassicMotion, I'm doing a build very similar to yours.  I had dual sidedrafts on my L20B, but they are just too finicky, and I needed something a little easier to work on.  I bought a Weber 38, and I also bought a manifold just like yours.  I am interested in copying what you did for the emissions block off and PCV port.  I think I know the PCV threads are 1/4 British pipe thread, but what did you use to plug the other two diagonal holes?  I'm having a hard time finding Britirsh pipe thread plugs.  You must have used 1/4 NPT?

[KlassicMotion]

hmm.... I don't remember what it was I used.  I just went through my drawer and found two matching plugs and tapped for those specifically....Wait, I do remember, I didn't use npt, I just straight tapped it to a certain depth, tightened the plug till it stopped, and used lock-tight.... Maybe not Ideal, but it's been working for a while now.

[UkieDime]

Just my 2 cents I have been running a 38/38 for several years with stock fuel pump and no regulator. As per Racetep technical the inside screw is in further. Also ran same carb on an overbored MGB with a Holley blue fuel pump for years-that sputtered with a regulator on it so I took it back off. The Holley blue pushes 6 psi I think-Cater has the correct flow/pressure electric pump but I cheaped out and just kept running the Holley.

 

KlassicMotion thanks again for the downpipe for my 620 back to square port head-truck runs awesome now but will need to be swapped back for Ca. smog at some point...PITA.

[KlassicMotion]

Your welcome.

[KlassicMotion]

Update; I upped the size of my idle air jets by one, as per the instructions, and I haven't had any dieseling issues yet...