TheSamba.com :: View topic - 32/36 not idling right after removing top.

Sun Jun 27, 2010 5:07 pm

Yes I put the top of the carb back on.

'75 1800 type4. Facet pump, Holley regulator, Holley 5200? progressive. So Weber 32/36 for practicality sake.

Brief back story.

The motor was running terribly. Running super rich and randomly dropping at least one cylinder. my first thought was dead needle valve. Turned out the regulator had jammed. A couple of taps set it straight.

When I took the top off the carb, this is more or less what I did:

*Removed fuel hose.
*Undid the screws on top.
*pulled the tiny pin out of the choke shaft and lifted / twisted the top to unhook the shaft from the butterfly lever and the little plastic plate the shaft goes through.
*Blew through the fuel inlet pipe on the top plate, and gently pushed the floats up until I could feel that my blowing wasn't going anywhere.
*Installation is reverse of removal.

Now it has a really unsteady, low idle, and sometimes just slows down and stops.

I should also add, after this I discovered that I had managed to block off the crankcase vent hose. After I fixed that it ran a bit better, but the breather issue existed before I pulled the top of the carb.

Everything in the carb looked really good. i'd say it had a rebuild not long before I bought it. It also looked cleaner than my OE duals ever looked even after a pulldown and thorough cleaning.

My questions:

What could I have done to it?

This one is a bit more complex and I haven't been able to find an answer.
Is the idle circuit only really active to a certain position of the throttle? Ie if I turn the idle speed screw too far, would the primary power circuit start kicking in and mess up any adjustment of the idle mix screw?

This is a real nuisance because I have been using it to jumpstart the seldom used "daily driver" because its battery seems to have gone funny and needs replacing. Now my bay will run for a while with its wobbly idle or even with something rested on the accelerator to speed it up a bit and the it will just slow down and die. :(

Sun Jun 27, 2010 7:33 pm

Not sure what you did, you will have to just go back in there and find out. Is the choke working smoothly and not hanging up?

The transition circuit is dependent on the position of the throttle plate. But since all the idle air flow has to go through the venturi, turning the idle speed screw in and out within reason shouldn't affect the transition much.

Wed Jun 30, 2010 9:29 pm

I went in for another look. I couldn't see anything out of place.

Now it barely runs at all! Judging from all the smoke and the sooted up plugs I'd say it is running super rich and flooding. I really need a crying face emoticon.
When I get the chance I'm going for the super scientific method of removing the carb from the base, sitting it in a container and manually energising the fuel pump. if the fuel flows, I've narrowed it down a lot.

The only other thing I can think of is that I upset the power valve. I prodded at the sprung shaft on the top plate and the bit at the bottom of the float bowl to check nothing was binding. Could have pushed a borderline diaphragm over the edge.

I'm also going to recheck the fuel pressure in case the pressure reg has drifted. It shouldn't have but leave no stone unturned and all that.

Wed Jun 30, 2010 10:37 pm

Alright.

I pulled the carb. There was some fuel and crap in the base bit. Fuel I can understand as I need to put the carb to full throttle to undo one of the nuts. the crap, well that is less clear. My bet is on the crankcase breather.

I sat the carb on a clear plastic tub and energised the fuel pump for a little while. When it became apparent that nothing was going to come out the bottom I stopped it. That means the needle valve is good.

Next came the test of dubious value. I connected the end of the fuel hose up to my pressure gauge. It just kept going up past the 6psi on the gauge around to the vacuum part of the gauge.
I don't know if the regulator is supposed to work with a dead-ended flow like that. I feel like it shouldn't but would like to believe it would.

What should I do next?

Thu Jul 08, 2010 4:19 pm

Update:

I'm perplexed.

Regulator fixed and holding a bit over 2PSI.
Oil contamination.
Tub test showed no fuel leaking by gravity or with fuel pump pressurized.
Swapped a couple of the worst plugs to get it firing and started it. Probably still running rich. It was only running with choke so the vac was probably higher than normal. Vacuum was holding a fairly steady 14"Hg.

In spite of my observations, it is obvious the next step is to focus on the float/valve assembly.
I doubt the floats are bad. If the plastic ones can become contaminated instantly there's a biiig problem.
I have been looking for info on checking the float valve setting. Lots of things hint at it but I haven't found anything that straight up says "Do ABC, and measure X distance from these two points. If adjustment is incorrect do DEF".

I also strongly suspect the power valve isn't all it could be anymore, or at least the diaphragm. haven't figured out a good way to test that yet.

Thu Jul 08, 2010 8:50 pm

Don't care if I'm talking to myself. I yanked the carb again. I _may_ be feeling some leakage when i blow hard into the fuel inlet. No matter what I am going to replace the valve. Trouble is, I'm having difficulties finding a source.

I remember the power valve shaft making a satisfying squish when I gave it a bit of a bush. Now all I can feel is spring resistance. When I pull the floats off to do the needle valve, I'm going to pull the power valve.

I plan on rejetting too. But a good baseline is hard to find. I might give wildthings' jetting a try especially if my power valve is dead.

Sun Jul 11, 2010 8:43 pm

I finally got around to pulling off the floats, power valve diaphragm and needle/seat assy.

I'm really perplexed.

diaphragm is in great condition. When installed I can actuate it with a bit of hose on the gallery on the top plate. no sign of leakage.

Floats feel feather light and seem to be in good condition. Unfortunately I don't have a scale to measure with.

Both needle and seat appear to be in perfect condition with pretty much 0 signs of wear. They look pretty new actually. They will be replaced anyway.

I want to check the float setting but what I have found on the 'web is vague.

I also wrote down all the jet sizes and will post them later.

Where would I get shims for the needle valve seat if it is just out of adjustment?

Mon Jul 12, 2010 12:37 pm

RatCamper wrote: Where would I get shims for the needle valve seat if it is just out of adjustment?

On most of these carbs there is a tap that you bend to adjust the float level. Kind of crude, but it works.

Mon Jul 12, 2010 7:45 pm

Is this only a problem at idle? If so, you may have got some gunk into the air passage that feeds the idle circuit. Try taking the carb off and spraying carb cleaner through the various openings to clean any gunk out.

Mon Jul 12, 2010 8:21 pm

cool, replies.

I found a fuzzy page from something online and some other scraps of info that tell me that the float should be set like this:

The bottom of the float should be 40mm away from the base of the top plate of the carb when the float assembly is touching the ball bearing in the needle assembly.

As odd as it sounds I couldn't find a ruler so I was forced to use digital verniers. Terrible for the job but they did tell me that the float is at maybe 37 or 38mm, so the float would be riding a couple of mm high.

So I bend the tab? Hm. i was going to try to get another rubberized shim, but then I have no idea if that is what it is or just a special gasket for the valve seat.

mnskmobi, I'll have to wait a while to get some carb cleaner. the closest place I may be able to get it is a good 3/4hr drive away, which is unfortunate. I haven't seen any signs of blocked passages or really any contamination but it will pay to check it out.

The over rich problem seems to be so no matter what the revs are.
I fixed the regulator's mysterious pressure creep, and this will hopefully fix the carburettor's sudden flooding fetish.

EDIT: I have the naming for primary and secondary backwards in this post. I am not changing it because it will make future posts confusing.

The jetting is as follows:

pri. idle: 50
sec. idle: 65
pri. main: 155
sec. main: 135
pri. air correct: 180
sec. air correct: 170

I didn't pull the emulsion tubes.

Don't anybody even think of using this jetting as a baseline. It is what was in the carb when I got it. It seems to be too rich, however there is no flat spot that I can perceive.

Incidentally, because this information is so damn hard to find I'll put it in here. A facet pump needs to be angled 45deg UP. Ie. the outlet is higher than the intake. Apparently it is to help stop cavitation. I have mine mounted the wrong way currently, but I don't think cavitation is my issue. I'll fix it later.
My instructions had an unfortunate accident shortly after I got the pump so I had to do it from memory.

Mon Jul 12, 2010 8:34 pm

leave the jetting alone for now. You will only add one more variable if you change it.

Mon Jul 12, 2010 8:41 pm

download, print and read this

http://www.thesamba.com/vw/archives/manuals/holley_carburetor/Holley_5200_Carburetor.pdf

Mon Jul 12, 2010 8:43 pm

SGKent wrote: leave the jetting alone for now. You will only add one more variable if you change it.

As it is the only way I can change it is by ordering jets online so they won't get changed just yet anyway.
Looking at what i have compared to others it would seem that it would be running a little rich, most notably that secondary idle.

Well, for now I'll give the float setting a tweak and hope for the best. I still need to change the oil though :(

Mon Jul 12, 2010 9:38 pm

Your secondaries are leaner than your primaries, this isn't right. Why don't you try swapping the primary and secondary mains and see how it runs. If it runs better then you know you are on the right track. You can always swap them back.

Mon Jul 12, 2010 9:51 pm

Wildthings wrote: Your secondaries are leaner than your primaries, this isn't right. Why don't you try swapping the primary and secondary mains and see how it runs. If it runs better then you know you are on the right track. You can always swap them back.

I missed that but concur with Wildthings. the 135 should be the primary and the 155 the secondary. Leave the air jets alone.

Mon Jul 12, 2010 10:07 pm

Wildthings wrote: Your secondaries are leaner than your primaries, this isn't right. Why don't you try swapping the primary and secondary mains and see how it runs. If it runs better then you know you are on the right track. You can always swap them back.

*dribble dribble* I'm an idiot. When I saw what you said I double checked what I wrote down. It was perfectly correct ...if it were a DGEV. But it's a DFEV.

Ignore the previous jetting. I won't edit it because it'll just confuse people more.

Does that mean I reverse the primary and secondary for everything where naming is concerned?

Just to ensure my dyslexic brain is sorted:

With the carb sitting on the desk in front of me, I have the barrels closest and the float bowl furthest.

The accelerator pump, electric choke and primary throat are on the left.

All that aside, I sat down with my verniers and fixed the max and min float level to within maybe .5mm. It is hard being more precise bending bits of metal.

Mon Jul 12, 2010 10:36 pm

Self reply.

pri main: 135
sec main: 155
pri idle: 65
sec idle: 50
pri corr: 170
sec corr: 180

That is the right way round now, I assume.

Primary idle may be a little fat, and secondary main a bit too big too.

Any idea what may be good replacements for a test? They aren't exactly expensive, but it will take time to order them / wait for them so I might as well get them.

Been reading conflicting things about the air correction jets. Are they the right way round?

Mon Jul 12, 2010 10:44 pm

Rat,, google holley 5200 theres afew sites, most talk about using those on watercooled.

There not the same as the webers, the passageways are drilled a different size, there bigger.. Ford tried there version before the holley/ weber.. those had motorcraft written on them..

Those 5200's I've yet to see any one get those to run right, there always very rich. I'm talking about using them on datsun and toyota engines,, on a VW T1 forget it.. don't know about a T4

The float level, ya. I gave up on the 40mm and just set the seam on the float level with the machine surface on the carb top. Then check by blowing, if it shuts off any where's close it's good to go.. They have a big float bowl so there pretty forgiving.. but we have more problems of carbs going empty not flooding..

I just took apart a weber.. only checked the mains pri 120 sec 105 pretty sure that one was used on a dastun LB 2000 with a closed chamber head..

this sound like your putting alot of time into this, living that far out.. I would switch jets, put the small one in the main. I can only guess by rich,, you are blowing black smoke,, maybe it will lessen..

also never trust the size on the jet, you never know if it's been drilled out and on the idel jets make dam sure the oring is on the jet holder..if it's not there they will suck air like a big dog. next to the vacumn port is a brass plug, kind of like a small freeze plug, I've had those fall out.. you would think any of these would make it go lean, but they go rich as hell and smoke black

Chit you still have the dual carb manifolds just put dual SU's on it.. In the olden days, (70"s) I worked for a guy that did installs of rayjay turbo's those kits came with a single SU, so afew years ago I did a turbo on my buggy , T3/4 and 1 3/4" SU That thing ran so smooth, plenty of power easy to drive, till the turbo hit boost. I keep thinking of using a SU on this bus screw the solex..

another carb setup, this guy knows his shit... he used two mikuni's not sure what size, but they were singles off some Bike, not the side daft type. This was on his wifes driver again just as smooth as can be..

Mon Jul 12, 2010 11:11 pm

Take a look at this link, it's for a T1 engine, but it will give you a guide line on jetting..

google ,, there's alot on thes carbs,,,,

http://vw.zenseeker.net/WeberProgressive.htm

Mon Jul 12, 2010 11:15 pm

Thanks for that towd.

There are so many damned variants, and all just as badly documented. I remember it says Holley, Weber, and Made in Italy in the float bowl so yeah. I dunno.

Been hoping for a cheap pair of centre float SU's to come up on e-bay. I was thinking the same reusing OE manifolds. I even considered using one of those crap carb adapters backwards to mount a big ol' single throat Stromberg on the Weber base.
i was even tempted by a single sidefloat 1 3/4" that came up for something like $25. Wouldn't need a tacho. The motor would suffocate before it redlined!

is there a difference between the 5200 and the G180? because it may be the latter.

you mean switch the idle jets? Can't hurt.

That weber you took apart has some small mains in it. That's really interesting.

I'll go through and check all the things you said when i get a chance. Hopefully soon.