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high load drop out

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Brian_C said:
I'm inclined to think it's a tank/filter issue, too. I had the same problem. The car would run great around town, but as soon as I tried to push it to 55+ the filter would get completely clogged. I had a ton of sediment at the bottom of my tank. New tank + new filter = no more problems. If you have the old filter, blow some carb cleaner through it and see what comes out.

If it's the tank, then the filters will just continue to get clogged (at the worst times, I'll add). My second filter lasted all of ~40 minutes of drive-time before it got stopped up.

B
Click to expand...
I had this problem years ago when I drove the car. I bought one of those clear glass filters that you can take apart and clean out. I put it right before the pump. You can just look under there and see how bad it is.
 
The filter I took off was see through, looked fine paper is a bit discolored. One I had on hand was a canister type so it is on there now, can't see into that one. I'll back burner it for a while while I tinker with other things.
 
Finally got around to moving the pump and it had no effect, that is still very low volume of fuel delivery-7gph. I figured I'd start with the pump move since it "should" be back there anyway. I had to cut the fuel line from the tank right near it's outlet (leak in the metal line) and I caught some gas it looked TERRIBLY dirty to me, I let it evaporate all day and the pan has a nice brown powdery crud in it. So it looks like I'll be dropping the tank next. Although I'd think it would eventually totally plug up or drop so low as to make it undrivable. This is not the case. I can run down the highway at 70mph for several minutes, then a bit later struggle to keep her going 40mph, could this be filter clogging and unclogging?
No matter, tank must come out and get treated, all filters replaced, then start over.
 
Yep, I would also bet that it is the in tank filter cloging and uncloging. Pull that tank have it cleaned and lined.
 
If your tank is rusty inside, you need to address it before driving too much. Loose crud in your carb will make it a bear to dial in later down the road. Seems you can never totally clean the small passages out. Rusty tanks have caused a lot of fuel delivery issues in many types of older cars.
JC
 
This could explain why the primary barrel on the Weber always looked so carbony, although the inside of the carb looked pretty good, likely thanks to inline filters. Alright, I'll drop the tank and fire up the grill. I have a Kreem kit already so I'll use that. That and new filters "should" resolve the fuel supply issues. I'll probably just nix the in tank filter and have an inline one right outside the tank, another just before the carb. As long as the original 1/4" ID metal lines are good yet, I assume I'll get close to 15 gph at an acceptable pressure after all is done.
Maybe if I'm lucky I'll be able to start tuning this thing before winter!
 
Make sure you are feeding the weber through the supply line and not the fuel return line. (assuming you have a DGV) Pull the lines off. One side will have a restriction in the line and the other will be wide open. The restriction is for cars that have a fuel return. Mine doesn't, I don't know about yours. Anyway, I made this mistake and was trying to push fuel through the orifice and had plugged the wide open inlet. The orifice is about 0.060" or so.

Just a thought,
JC
 
Interesting on the different inlets. I assumed they were the same, just right or left for different applications. I was going to move the inlet to the other side to get the supply line away from engine heat but now maybe I won't. Both Weber's I've dealt with had one side still "plugged" (as in never opened after the casting). Ironically my last Weber (38/38) had the inlet on the wrong side (its right), I moved it to the other with no negative effect. This 32/36 is on the carb's "right side" but should really be on the left/outboard side. Not a big concern though.
I suppose if you buy the Weber DGV for a certain application, it would come with one side or the other opened.
Anyway, my fuel flow measurements thus far have been right before the carb and it's a trickle, measured at 7gph. Where exactly the hold up is I don't know but since new inline filters didn't do it, and different fuel pump didn't, and moving the pump didn't I'm assuming the tank filter itself is clogged. There were actual chunks of goo that shot out when I cut that line.
Be nice to put this issue to bed and move on to the next. Soon I'll have this thing totally road worthy (although I've put 1200 miles on this summer as it is!)
 
Your engine consumes the same amount of fuel at a given RPM wheither the car is in 1st gear or 4th gear, so I'm wondering why the difference. Are you sure the ignition timing is correct? At cruise in 3rd or 4th you'd be seeing a lot of vacuum advance and then drop it back as you opened the throttle. I think I'd have the distributor and vacuum advance unit checked.
 
Oh sorry about the bum advice. I guess I should have read the whole thread. Good chance it is the inlet in the tank. You may have trouble with that after you seal the inside of it too. That is why I just bit the bullet and bought a new tank and sender from VB right after I bought the car. The PO had put a bunch of filters in series before and after the pump trying to capture the rust...lol What a mess.
JC
 
If you do seal it your going to what to poke a hole in the pickup screen Heck it may be all you need to do now... Then put a pre pump filter on it. Something clear and large.
 
bill_young said:
Your engine consumes the same amount of fuel at a given RPM wheither the car is in 1st gear or 4th gear, so I'm wondering why the difference.
Click to expand...

That can't be true. Doing 3500 RPM in first, the air resistance is negligable compared to doing 3500 in fourth gear.

Also, that's assuming no accelleration or decelleration, which is rarely the case. Going from 2K to 5K in first and going from 2K to 5K in 4th is drastically different in terms of work performed, and therefore fuel required.
 
This is a tricky subject. I think it is dependant on engine rpm and not what gear your in. I say this because you can only cram so much air in a cylinder per stroke. That air moving is what is causing the entrainment of fuel in the carb. So at a given rpm you would use a given amount of fuel assuming the air/fuel ratio isn't changed by the slight increase in pressure under the hood from the speed.
I could totally be wrong though.
JC
 
Eingine is a pump if you could have a flat curve it would use the same amount of fuel for a given amount of work - time - distance but we know the curve is no where near flat.its al in the curve effenecy.
 
Went trolling around the archives a bit and found this in post 430436
"Did you check the flow ahead of the pressure regulator? If the adjustment is off or slipped, that might be where the restriction is. I'm a little wary of pressure regulators. In general, they work well only within a range of flow rates. In a LBC, the flow starts and stops as the float valve opens and closes, and I'm not sure how the regulator might respond. Might be better just to have a pump that puts out the right pressure (2-3.5 psi)."

So, for fun I pulled the line BEFORE the regulator, stuck the hose in a 1 liter bottle and turned on the pump....and quickly turned it off because it was filling FAST!
Regulator all along? Probably could have left the pump where it was!.
I did not check the flow rate but it has to be 3x what it was, probably more.
So I tore down the regulator expecting to find something. Nothing looked wrong. I have a spare but I really wonder if it needs one at all. The pump on the car now is a Stewart Warner and probably 5-7 psi. That's probably close to too much for a Weber.
 
Remember that it doesn't take long to reach redline in 1st and 2nd compared to 3rd & 4th. The extra time spent @ full throttle in 3rd and 4th could empty your float bowls. Where a short blast up to redline in 1st would not.
 
I put a different regulator on it, checked fuel rate.
1 pint in 21 seconds is about 21 gph (check my math!)
Bet that should do it!!
Pressure regulator set on 3. Not sure how a regulator that dials down pressure doesn't effect flow, I suppose it does. Seems hard to get 30gph at only 3 psi but whatever.
Not that the tank isn't filthy and could use a good clean but it sure looks like the pressure regulator was garbage.
 
I've got the Holley low pressure regulator on my car. It is a bit large for my taste but it sure does the trick. It doesn't seem to restrict flow at all down as low as 1.5 psi. I've since cranked it back up to 3.0. I can look up the model number later if your interested. Ok later just came. I got the 12-804 but the 12-500 will work too. The 804 is chrome. I picked it because I found it cheap on Amazon. Anyway, they are good down to 1psi.
JC
 
Thanks, The two I had are similar dial style, like :
these

I took the "bad" one apart, expecting goo or sludge or something, but it looked just fine. Probably the dial portion (simple tapered needle design) was not opening like it should.
The new dial one is the same design but is letting gas through much better, quick test drive last night (early this morning, truth be told) and I did not have any issues although too soon to know.
 
As you've discovered, those are fuel RESTRICTORS not regulators. The Holley one is what you should be using. Not to mention that the round ones did (and maybe still do) have problems with "modern" fuels... they leak, and the diaphragm perishes.

Peter C
 
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