Carb loading

[krewzer]

I have developed a problem with my Weber 38. After a high speed idle warm up, the GT settles into an idle and stumbles. I can see fuel dripping onto the throttle plates and the motor shutters, shakes, and dies. I recently relocated the fuel inlet to the fender side, and have twice gone completely thru the carb to make sure there aren't any loose bits. I have even swapped a couple of float needles and seats. I've checked float level several times. It's brass and I'm setting to 41mm and 51mm. It seems that the needle isn't seating and shutting off the fuel flow. I have good vacuum, around 12, and the accel. pump is in great condition. Should I monkey with the float level, buy a new carb, maybe a 32/36? My setup is 2.0l, OR66 cam, big valve head, moderately ported intake, Sprint exh. manifold, 2" to 2.5" at the tail, Compu-fire ignition, modified/adjustable distributor. She's a real runner! Oh, and lastly, I'm hosting the Texas Opel club meet at my house next weekend. There can't be anything worse that leading the fun-run in a minivan.
Please help!
Wes

[baz]

whats your fuel pump ? weber's dont like much pressure and can flood out the carb easy

[krewzer]

Carter, and it pushes just under 3 lbs. per the fuel pressure gauge, mounted just in front of the carb.

[wrench459]

The float level,drop and fuel pressure specs looks good.
How about the float weight? I don't have the spec for it.

[krewzer]

Float weight? I didn't know there were variables with weight. I can say that the float in this carb is not the one supplied originally. I pulled a brass one from an older Italian 38, and replaced the plastic float that it came with. Should I try the plastic float? Would it weigh differently? I got rid of my gram scale after college, so I can't compare them.

[krewzer]

Well, neither the plastic or the brass float (both properly adjusted) made any difference. Don't know where to go from here. Six days til the meet, and not even close to having a running GT. Jeeeez....

[wrench459]

Is this just an idle problem? How does it run going down the road?

[N61WP]

Wes,

I had the same problem with a 38 (new) a few years back before changing to a side draft. The same fuel pump that worked on the previous 32/36 would flood the 38 during idle. I tried different pumps, floats, settings and even tried a Grose Jet, which is a ball and seat that replaces the stem and seat...all to no avail. I finaly had to install a regulator that would bring it down to about 1-1/2 psi.

I started track daying the car and would empty the fuel bowl on the 38 in 3rd gear so I installed a SSD 45 Weber and removed the regulator. The 45 didn't flood with the same fuel pump. I don't know if this is just common to the 38's, I never found a cure other then adding the regulator. Sorry.

James

[krewzer]

James, thanks for your response. The regulator would be an easy fix. Did you have any problems with the 32/36 other than on the track? My GT is a only a street car. I am also working against the clock with only 5 days to solve my problem. I have had both carbs. The 38 seems to be easier to tune, so I would love to keep it. I'll try the regulator in the morning, and post the results. If it doesn't do the trick, I still have time to get a new 32/36 from OGTS before the end of the week.

[krewzer]

Wrench, the problem is all at idle. She is a screamer on the road.

[wrench459]

I'm probably wrong here.
But it sounds like somewhere along the line the throttle plates got opened up.
Your not in the idle circuit at all.

[hrcollinsjr]

Originally Posted by wrench459 Is this just an idle problem? How does it run going down the road?

What is your idle speed and what is your initial timing advance setting? Stock initial advance won't cut it with this set up. Once you've figured out what initial you need to run then you're going to need to figure out how you're going to limit your total timing advance. Been there done that with the Isky OR-66H cam in a 1.9 32/36 equipped car w/header and stock valves.

Harold

[krewzer]

I'm at 10 initial and all in at 35. My distributor is modified with an adjustable advance limiter. I have never been able to idle under 1000 rpm.

[opelwasp]

What main jets, idle jets, and emulsion tubes you have in it?

[krewzer]

150/180/f66

[hrcollinsjr]

Originally Posted by krewzer I'm at 10 initial and all in at 35. My distributor is modified with an adjustable advance limiter. I have never been able to idle under 1000 rpm.

You can possibly bump the initial a couple of degrees and leave your advance limiter so that you have 37 total but that still doesn't fix your idle.

I noticed Opelwasp asked about your jetting. I think he may have hit on your problem.

Harold

[krewzer]

Can you clarify your jetting concerns. I'm not the only member with a modified 2.0l, at sea level, using this range of jetting. I'll try anything suggested, as long as my mechanical abilities can manage the changes.

[hrcollinsjr]

Originally Posted by N61WP Wes, I had the same problem with a 38 (new) a few years back before changing to a side draft. The same fuel pump that worked on the previous 32/36 would flood the 38 during idle. I tried different pumps, floats, settings and even tried a Grose Jet, which is a ball and seat that replaces the stem and seat...all to no avail. I finaly had to install a regulator that would bring it down to about 1-1/2 psi. ... I never found a cure other then adding the regulator. Sorry. James

Found this post concerning your problem.

Originally Posted by N61WP It has been a good carb, except that it was more sensitive to fuel pressure then the 32/36 was. I had to add a fuel pressure regulator to keep it from flooding.

Originally Posted by RallyBob Installing a smaller fuel inlet needle from a 32/36 helps here. The 38 DGAS has a larger needle and seat, which is great for higher flow, but not necessary on a stock or nearly stock engine.

Did you try this? If so, could you tell a difference?

Harold

[hrcollinsjr]

Originally Posted by krewzer Can you clarify your jetting concerns. I'm not the only member with a modified 2.0l, at sea level, using this range of jetting. I'll try anything suggested, as long as my mechanical abilities can manage the changes.

I've not jetted a 38 yet so I'm not qualified to make any suggestions. What idle jets are you using and how many turns of the idle mixture screws to get best idle?

Harold

[opelwasp]

Originally Posted by krewzer The 38 seems to be easier to tune, so I would love to keep it.

Wrong, the 38 is a PITA to tune. I've had mine for 10 years and still haven't gotten it right. On small engines(1.9) it would flood and bog, on my big engine(2.4) it leans out at high rpm. I am so fed up I am switching to EFI.

When I did have it dialed in close it screamed.

[krewzer]

I have tried the size 200 seat from a 32/36, but the carb was over filling and I couldn't tell if it made any running difference. Right now, I have 55 idle jets in it. Before the problem occured, I was running 70's with no problem. I think the problem came from rerouting the fuel line to the fender side. Last year, I replaced my fuel line, and routed it around the radiator to the fender and the to the carb. I was still using the engine side of the carb for inlet. Consequently, the fuel line had to make a tight radius turn to the nipple at the inlet. It's a rubber fuel line with a ss braided outer. I think the tight radius was pinching the line just before entering the carb., and the inline fuel gauge was plumbed ii just before the turn. It read 2.5-2.75 psi . Now my line is a straight shot into the carb. Maybe too much fuel pressure after that. I'm running to the store to get a regulator. Maybe we'll have an answer soon.

[hrcollinsjr]

Originally Posted by opelwasp Wrong, the 38 is a PITA to tune. I've had mine for 10 years and still haven't gotten it right. On small engines(1.9) it would flood and bog, on my big engine(2.4) it leans out at high rpm. I am so fed up I am switching to EFI. When I did have it dialed in close it screamed.

Here is a link to a thread where they were tuning a 38 on a 2.4 engine. Maybe your jetting isn't that far off. Wish I had some experience with the 38's. I don't jet my 32/36 carbs like a lot on the list and they always seemed to run fine with good mpg. My initial jetting for 32/36 carbs was derived from an import place ordering a replacement carb for a 2.0 BMW. It seemed to work with no problems so I never changed it much.

Harold

[jmbinjax]

I'm having a similar issue with my 38. I've been considering a pressure regulator. Can someone recommend a universal, adjustable regulator?

Thanks!

[krewzer]

I just bought a $25 Spectre adjustable regulator that adjusts from 0-5 psi in 1/2 lb increments. It was all I could find in a short amount of time, locally. Autozone has them in their "performance" section.

[jmbinjax]

I saw that one but the reviews were 50/50. Some indicated it stopped working after a short time and one indicated it started leaking. Others said it worked great.