Warpy Carburetor

Bookwus · Post by **Bookwus** » Thu May 28, 2009 3:44 pm

Hiya All,

It seems that my gassy smelly problems have returned.

Yes, I've tried Beano.

But this is about my carburetor. After a run whenparked in the garage the Bus releases a distinctly gassy smell. I think I've found the cause of said smell. When I felt around the base of the carb last night it was damp with gas.

So, I pulled the carb today and took a close look. It appears that the base mounting is warped. I placed the carb on a level and I could get my .004 feeler in between the base (at center point between the two studs) and the level.

So, a couple of questions. Is .004 enough of a gap to cause a leak? Or should I be looking for some other leak source?

And I guess I'm looking at 220 on glass? Is that the preferred technique here? Any other ways of going about it? Any tips, hints, or tricks?

Hippie · Post by **Hippie** » Thu May 28, 2009 3:51 pm

Hiya Bookwus,

I would think the gasket would seal at .004" but maybe the throttle plate bushings are worn out.
I had Keifernet rebush mine for that reason. Problem fixed.

Bookwus · Post by **Bookwus** » Thu May 28, 2009 3:55 pm

Hiya Hip,

Actually, this carburetor too is a keifernet "alum". It has only 2000 miles on it since it left Keith's care.

I am reasonably sure that it is leaking at the base, but not absolutely sure. Like you, I'd think that a gasket would take care of a .004 gap.

I will do the "plane the bottom" routine but I was wondering if there was anything else I should be looking at.

vdubyah73 · Post by **vdubyah73** » Thu May 28, 2009 4:19 pm

Don't be a wussy. Take a good mill bastard file and lay it flat across the flange and just work it. Been fixing flanges this way for decades, learned it in the Navy.

Bookwus · Post by **Bookwus** » Thu May 28, 2009 6:15 pm

Hiya Bill,

vdubyah73 wrote:Don't be a wussy......

Geez already! Take another look at my handle!

vdubyah73 · Post by **vdubyah73** » Fri May 29, 2009 2:35 am

It's guy talk, sorry if I offended shoulda used a smiley. I honestly didn't make the connection.

With 220 on glass you'll be a month of Sunday's doing it.

Hippie · Post by **Hippie** » Fri May 29, 2009 4:22 am

Bookwus wrote:I will do the "plane the bottom" routine but I was wondering if there was anything else I should be looking at.

Fuel line nipple into the bowl? Top carb gasket? I'm out of ideas.
Guess I'd plane the bottom then, too.

Randy in Maine · Post by **Randy in Maine** » Fri May 29, 2009 5:06 am

I use a piece of granite countertop my buddy gave me instead of glass to do things like this and use the "stick on" sandpaper to attach it there.

Works pretty good.

Post by **Amskeptic** » Fri May 29, 2009 5:21 am

Let's not forget that the cause of the gassy smell has not been addressed.
Just because you found where the gas is leaking out, doesn't answer why gas is leaking out there in the first place. VW had nice cut-offs in the fuel pump to prevent percolation. Replacement pumps don't. I am testing a pressure regulator as we type, and will let you know if it prevents percolation in the carbs when it is hot out, which it isn't around here in the rainy almost northeast.
Colin

Bookwus · Post by **Bookwus** » Fri May 29, 2009 5:38 am

Hiya All,

I was thinking along the same lines as hippie. Namely that .004 didn't seem to be that much out that a gasket wouldn't make up for it. But the real eye opener was when I placed the carb on a flat surface. It rocked from side to side. Not much, but it did rock.

So, I went at it with the glass and sandpaper routine. Actually Bill the sandpaper cut through that bottom flange mount pretty well. I was only at the job for about 10 minutes. The carb now sat flat on both the glass and the intake manifold flange. Reinstalled it along with new base gaskets and took her out for a road test. Drove really well. And it was dry as a bone sitting in the garage afterward.

I think this may have done the trick.

And Colin, I'm not too impressed with this new fuel pump I've got. Measured out my fuel pressure at about 4.5 I'll be gasketing this thing to reduce the fuel pressure a bit.

dtrumbo · Post by **dtrumbo** » Fri May 29, 2009 6:12 am

Hiya Mike! (Sorry, had to do it!)

I'm goin' to school on your findings here. As I mentioned, I have a very similar issue and have long suspected (but haven't done a damn thing about) fuel pressure. What it the "correct" fuel pressure for carburetors? I know FI runs quite a bit higher, but what number should I be shooting for on my Type 1 with dual Webers?

I'll be pulling the engine/transmission (AGAIN!!!) after we get back from Maupin so I plan on addressing this issue (finally) at this time.

Bookwus · Post by **Bookwus** » Fri May 29, 2009 6:25 am

Hiya Dick,

3 seems to be the magic number in a stock set-up. Actually, I believe it's a range from 2.5 to 3.5.

Bob (Hambone) went through this scenario when he rebuilt his engine recently. His fuel pressure was quite a bit over spec and I think he settled for about 4. His engine performance (he had been stalling out at the bottom of long hills) was much improved.

Basically the same for me. My engine was stalling out when coming to a stop at a traffic light or on the long downhill routine. I've done some shimming of the fuel pump and dropped my fuel pressure from over 4 to mid 3s. I'm still checking out the results (and fiddling with the carb base)

I'm thinking that a big part of my problem is the new fuel pump I'm using on this rebuild. It's the newer "one size fits all" style from Brazil. I'm not too happy with this thing so far. We'll see how everything plays out here in the next couple of days. I may be going back to the older style pump.

vwlover77 · Post by **vwlover77** » Fri May 29, 2009 9:29 am

My questions regarding the hot percolation are these:

Is the needle valve actually forced open by the pressure that builds in the fuel line during heat soak?

Is this pressure higher than the pressure developed by a running engine at idle?

dtrumbo · Post by **dtrumbo** » Fri May 29, 2009 9:38 am

Thanks Mike. I have no complaints with how her bus runs, other than while it's warming up it "coughs" once in awhile (is this too much fuel or too little?). I'm sure the 009 distributor isn't helping. It also idles high after a nice highway run. I'm thinking crappy linkage possibly adjusted too tightly is to blame there.

I've often thought that excessive fuel pressure might be contributing to the stink after shut down. What shoots holes in that theory is the bus never floods. Always easy to start, hot, cold or otherwise. In any case, I'll check it before I do the forthcoming pull and we'll start down that road in addition to checking/correcting leaks like you found on yours.

vdubyah73 · Post by **vdubyah73** » Fri May 29, 2009 3:17 pm

I always thought that the higher idle after a good highway run is a result of adjusting timing and idle at "around town" operating temps. I have adjusted timing and idle after a "highway" warm up and idle is low around town. So I've taken to adjusting at "around town" temps and rationalizing that a higher idle after a highway run helps cool down the engine on surface streets, before arriving at my destination.

Bookwus, glad you weren't there forever, getting carpal tunnel or sumpin'.

Itinerant Air-Cooled

Itinerant Air-Cooled

Warpy Carburetor

Warpy Carburetor