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Fri Mar 19, 2010 3:38 pm

I'm thinking that this is probably contributing to my low oil pressure problem that I've been having, gasoline thinning my oil.

I had noticed previously what I thought was water dripped out by my tailpipe, and after it's been sitting, will blow white smoke out the exhaust upon firing up.

I had the bus on a jack stand at the front driver's side (tailpipe opposite, type 4 engine), left it overnight, and came back this morning there was a giant puddle of gas, still dripping out the tailpipe. I couldn't believe it, took the tailpipe off and it came pouring out.

I'm thinking there's something wrong with my carb, at least the right side one? They are Dellorto drla 40's. I've had them on there about 2 years now without problems. -I'd got these off ebay from a guy, gabriel who is in Italy and rebuilds them, has a flow bench to set.

I have rebuild kits for them, and also update kits from cb performance. I've been waiting for an excuse to install these, since I didn't want to mess with the new rebuild.

Ultimately I'm gonna have to take stuff apart, but wanted to know if anyone has any advice/ if anyone has had this problem and knows exactly what's up?

Fri Mar 19, 2010 3:43 pm

sounds exactly like one of your float valves isn't seating, so it keeps filling even after you turn off the engine. it will flow thru the carb, down the manifold, and into your cylinder. and out your open exhaust valve, into your exhaust. it can also be getting by the rings into the crankcase.

the tank is mounted high in a bus, so gravity will keep filling it.

if it is not the valve itself, you could have a float that is heavy or sinking from a pinhole in it.

Fri Mar 19, 2010 3:48 pm

don't try to turn it with the starter or you may hydraulic it. turn it over by hand first. AND I would get it out of the garage before trying to start it in case it blows a big cloud of gasoline droplets out that ignite into a fireball. Might want the fire truck standing by on this one if there was that much gas. The muffler could be full too.

Fri Mar 19, 2010 4:23 pm

I'm thinking definitely change the oil, take the muffler off and dump it, wait a little bit for some evaporation, definitely open the garage door prior to starting again.

I've got the dellorto super performance tech book to reference, so hopefully I'll be ok.

Almost off work, here so you know what I'm doing this weekend. No internet at the shop yet so i won't be able to check again before diving in.

I've never rebuilt a carb before; this should be fun :-)

Fri Mar 19, 2010 4:35 pm

nathansnathan wrote: I'm thinking definitely change the oil, take the muffler off and dump it, wait a little bit for some evaporation, definitely open the garage door prior to starting again.

I've got the dellorto super performance tech book to reference, so hopefully I'll be ok.

Almost off work, here so you know what I'm doing this weekend. No internet at the shop yet so i won't be able to check again before diving in.

I've never rebuilt a carb before; this should be fun :-)

really, you dont need to rebuild the carbs. you can fix this issue without changing yoour settings and syncronization. you should be able to fix the needle valve, or replace the float without too much harm to the initial settings. if you take the covers off and it looks real dirty in there, then, yeah, probably would be a good idea to clean them at least. i mean, it could be a piece of dirt holding that float valve open a bit.

if you are going to take them apart thoroughly, take each adjustment screw, and screw them in, until they stop, counting the number of turns, so when you put it back together you will be very close to where you were when you started. if you have never rebuilt a carb before, dual carbs are not the easiest things to get working in harmony with eachother.

do you have a carb sync tool?

Fri Mar 19, 2010 4:40 pm

hmmm, I will try this, taking the 'top' off without removing first. I do have 2 actually of the 'snail' flow tools. I used to mess with my weber 34 ict's all the time, though I never did get them to actually work quite right. -These have a lot more adjustment on them so I've been reluctant to mess with them much.

Good idea about counting turns, I will make a point to do this, probably even draw myself a picture.

Sun Mar 21, 2010 11:59 am

So I got apart. The needle inlet valve looked a bit worn but seemed to work, holding air when I tried blowing into it.

I'm thinking the problem is to do with the float level adjustment as it was way off from what the book said it should be. In the 'up' postion (closed valve) the floats were pretty much touching the top plate and down was like 25mm down - the book says 5 or 6 from the top when up, 13-14mm from top when all the way down. So I adjusted it per the book. Do the floats un-calibrate themselves through use or did the dude set them up that way do you think?

Besides this, to complicate things, I succumbed to temptation and installed the update kit, which you plug these 2 little air inlet holes, install 'horizontal discharge tubes' and also modify the idle jets to take air from up in the air cleaner instead of ... not sure how air got to those before actually.

So, it's back together ( removed and drained the muffler and angled it back pretty good for awhile to get the gas out of the heat exchanger).

I spent some time trying to synch and adjust. It seems to bog down now when I open up the throttle. I'm wondering if the 6mm/ 14mm float adjustment is the spec for a 1600? Mine's a 1.8. Maybe I should try for like 20mm down?

Sun Mar 21, 2010 12:59 pm

do you have a fuel regulator are you getting about 3 1/2 psi off the fuel pump?

Sun Mar 21, 2010 1:12 pm

yeah, I do have a regulator -it's set to 3 1/4 psi.

-thing is they ran pretty good how they were - despite the inlet valve never closing.

I can't seem to find anything about float levels; people are talking about jets.

I may have to bust out my gunson color tune, I wish I had an LM-1 :roll: ...or programmable fuel injection, that seems nice

Sun Mar 21, 2010 1:34 pm

O.k. but is the fuel pump pumping out what you need.
your going to get fuel starvation at higher rpm if your fuel pump is only pumping out let say 2 1/2 psi @ 5000rpm

EDIT: you'll get better info out of Performance - Engines/Transmissions forum

Sun Mar 21, 2010 3:28 pm

If I remember right, this was a common problem with dellorto's. I bet that Art Threan at ACE could probably help with it.

Sun Mar 21, 2010 9:20 pm

3lbs is all you need. Verify that you have it with a gauge. If that checks out then it's either a needle/seat issue. Is this a mechanical pump or electric?

If mechanical it could be a bad fuel pump diaphragm.

Mon Mar 22, 2010 8:07 am

Ah, looking again, I was reading the gauge wrong, it is 3 1/2psi. VDO in compartment gauge into a holley regulator, carter rotory pump. I was afraid that with this wheelie-popping update kit that my regulator was the bottleneck even, but I'm thinking no. 3 1/2 or 3 should be about the same, mostly. -I don't want to change too much right now, like time it or tuneup, until it's back where it was. -besides the gas out the exhaust it ran alright. I'll try 3 later.

I've posted over on the shoptalk forums type 4um. Funny the thread I dragged up to do it, Jake mentions the same Art Thraen @aircooled engineering in Salt lake city.

http://www.shoptalkforums.com/viewtopic.php?f=1&t=1681&p=1005046#p1005046

It may be now that I have 2 problems, "PROGRESSION PORT LEAKAGE" and now just poor performance, either due to this update kit or else the adjusted float level.

I stayed up late de-updating the carbs, and all should be as it was except the lead plugs and the idle jet holder, and the rebuild needle inlet is 1.7 instead of 1.5. I haven't gotten to try it yet as it was after midnight and no time to be synching carbs. I'll be able to test after work, post back tomorrow the result.

Mon Mar 22, 2010 8:29 am

About the fuel pressure/demand, since the gauge is in the engine compartment, I can't tell if, when I put a load on it, if the fuel pressure drops.

I would think with the electronic rotory pump that it could meet the demand, especially being regulated down to begin with. Revving it in nuetral (from the linkage), the gauge remains at 3 1/2 . -but then it doesn't seem sluggish when I'm revving it in neutral.

Probably though, I'm thinking there's no need to set the fuel pressure 'at load'.

Mon Mar 22, 2010 10:58 am

if you are geting that psi at low rpm then it should not be the fuel pump, good thing you pulled that update kit there a few wright ups on Engines/Transmissions how to get them to work Dave the carb guy at aircooled engineering suggest agents using them and always pulls them out of the carbs they are going to work on, the jet doctors are fine and left there.

now it's sounding like you may need larger main jet, are you using all the jets from the kit? or did you mis and mach ?

with engine off get a mire or open the engine hatch and make sure you get a steady stream out of the accelerator jet when you pump the gas.

this may be silly but the is the regulator after the fuel pump and is the gauge attached to it?

Mon Mar 22, 2010 12:10 pm

I put up a 'chart' on the stf thread, including the stock, my original, and what came in the update kit as far as jets. I used everything from the kit, and have now taken all but the plugs and idle jet holders off.

I will look in the barrel upon applying gas. gonna have to use the 'mire' unfortunately. :-) - The downfall of the 72 model year being no hatch.

The holley regulator is a 'T', 1 in 2 outs, easy for double carb setup. With the Dell 'double banjo' my plumbing goes: fuel tank> plastic filter> fuel pump> regulator. Then 1 out of the regulator has the gauge, other out goes to the left carb, then off the double banjo to the right carb.

One thing I noticed is the left carb intake was pretty hot while the right carb intake was coldish, after running it yesterday, all mixture screws set to 1.5 turns out. -I wish i would have left those alone, I got confused thinking they were the air correction screws. :roll:

Mon Mar 22, 2010 1:21 pm

most of the vw dellorto are set up for light bugs and porsches so you'll want to think about that.

the good news is that kit has jets that you can use on your bus nice and rich.

for a ruff idea on jetting read this http://www.vw-resource.com/jets.html

ah merde :oops:

Tue Mar 23, 2010 7:49 am

When I got these things, rebuilt, from the guy, I asked him to set them up for an 1800, and they ran pretty well. It's hard for me to say as I've only ever driven 1 other air-cooled volkswagen ever, a very squeeky 18 window split. I would take my bus on the thruway. My bus is like a normal car, a slow normal car, mind you. :-)

The reason for this is now apparent, I'd felt it getting weak, and checking compression, it's at 90 all around, except #3 which I have to shoot oil into and crank extendedly to get it there. Dry, it read 65.

I'd anticipated this, and have been building a new engine in the meantime. I have an aligned bore case, bearings for it, a polished inspected 66mm crank, rebuilt set of rods, AE 1800 pistons, uncut manton pushrods, clutch disk, gasket set and both seals, a rebuilt alternator.

I'm almost thinking now would be the time to do the deed.

But then I'm thinking I should fix these #%*^# carbs first because I don't want to break in a new engine with it bogging down like this. Oh yeah, having taken out the horizontal discharge tubes and cb performance main venturi back to the original stuff, I'm still not able to get it right.

I'm thinking maybe that something 'happened'. I'd made a killer trip to the inland empire to get a sandblaster cabinet, and it seemed a bit more pissed off than usual. I drove it the day after and it did seem a bit off, precariously balanced on the brink of total need of teardown?

I'm thinking of getting some help on these. I am so bummed that I can't seem to fix my shit. I want this thing:
http://miami.craigslist.org/pbc/pts/1632175976.html

I'm not sure if it's something I did or what, but I can't get, say, barrel 4 and 2 to be even at both idle and revving. Like if at idle they're both drawing '4' on the snails, when the left (4) is revved to '7' on the snail, the right will be at, say, '5'. I've done this before and it all seemed kosher. Is it, do you think, the mixture that's messing it up, something I did, or maybe is the engine, even? ..or just me :? -Makes me wish I had Solexes so the vw-resource jets article could tell me exactly what's what. There's a shortage of info on these dells, still no idea about the floats.

God, I am so bummed to be driving this rented 2008 automatic nissan sentra. All cars should have curtains. :-)

Thu Apr 01, 2010 7:49 am

Got a bit wordy there...

I rebuilt the engine, got it back in and still carb problems.

Getting really intimate with it, like lips on the banjos blowing through things, I realize with the floats set per those instructions that the needle valves aren't opening enough to let gas through barely.

The new needle valve from the cb performance rebuild kit is different. Even though it is a 1.7 instead of 1.5, the width of the square sliding part of the valve is smaller. By squeezing the float's forked tongs that pull up on the valve together I made less play between open and closed, and also lowered the float limit, I got it flowing better there.

It's still seems a bit starved for fuel though, popping at 3000 rpm or so (main circuit) unless the mixture screws are out by like 3 1/2.

I'm going to try a 1.5 main fuel jet instead of the 1.2 just because I have those from the kit.

I'm trying to get it looked at but I'll have to wait 2 weeks at least to get it to the shop. I'm trying to get 'old speed' to look at it, but they're busy of course.

Thu Apr 01, 2010 9:18 am

nathansnathan wrote: Got a bit wordy there...

I realize with the floats set per those instructions that the needle valves aren't opening enough to let gas through barely.

By squeezing the float's forked tongs that pull up on the valve together I made less play between open and closed, and also lowered the float limit, I got it flowing better there.

I'm going to try a 1.5 main fuel jet instead of the 1.2 just because I have those from the kit.

sounds Like the needle hook got maladjusted if you cant get any flow with the floats set right.

I had 1.4 main and 180 airs when I got my carbs, I have the jets from the kit in now I'm still figuring out the jetting for dell's but 1.2 mains sound way to small for any thing over a 1700.

looking at this your mains and vents look small the kits vents are the stock size 34 the guys in the performance section are better at jet vents ratio than I.

Idle Jet
Stock .60
Original .57
Update -
Jake 55-60

Main Jet
Stock 1.4
Original 1.2
Update 1.5
Jake 1.4

Air Correction Jet
Stock 1.8
Original 1.8
Update 1.6
Jake 1.8

Accell Pump Jet
Stock .35
Original .33
Update -
Jake .35

Needle Inlet
Stock 1.5
Original 1.5
Rebuild 1.7
Jake -

Main Venturi
Stock .34
Original .30
Rebuild ? EDIT: 34
Jake .34

Emulsion
Stock 7212.2
Original 9164.2
Jake 4160.2