Difference between 34 PICT and 30 PICT?

In use on a stock 1600 DP in my '74 SB. Apparently, the older 34 PICT 3, although it ran great last week, has developed a problem that rebuilding will not fix (although it cleaned up
beautifully). Won't hold an idle, constantly stumbling at takeoffs from stoplights, etc. My mechanic wants to put a new 30 PICT (Brosol) on it instead of the standard 34 PICT. He says that they are used as replacement carbs on 1600's all the time with better success than the 34 PICT's (mainly due to their ability to rebuild without the problems I'm experiencing on the 34 PICT). I would be happy to listen to any thoughts or experiences as regards this situation. Thanks, Rich
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Seems odd that the carb was OK last week and now can not be cured with a rebuild. I would carefully check over the carb again, make sure all of the plugs (especially the one at the bottom of the fuel bowl which keeps a check ball in place), emulsion rods, and other easy to overlook items are in place / OK. The Bentley manual has a great carb section with all the detail you could ever want.
The Brosol / made in Brazil/Mexico replacement carbs are of much lower quality than the original german solexes - I have personal experience to back that up and have read the same here and in other forums. If your original carb is damaged to the point that it is not fixable (and you are not pressed for time), I would try looking for a good core to rebuild (an easy DIY job) or buy a rebuilt german solex from a vendor. The price diff will be minimal and you will have a better quality, less troublesome carb in the end.
================================ " ..... I ain't no bandleader!!"
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Richard Golding wrote:

The 34 is already small, but was what the factory out there. The 30 is really too small. Plus the jetting needs to be changed to make it work right.
Fix the 34 or get a replacement 34 if you want the engine to run right.
Jan
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Hi. Try switching the main jets(30 to 34).I think the 34s have bigger mains(for warmer clime & bigger motors.) Or try fiddeling a few degrees with timing.Steve

1600's
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They don't develop an unfixable problem in one weeks time.
Jan
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Umm.. let me add to that. If it's really an unfixable problem, chances are it's been having issues more than one week and building up to the breaking point, like really worn shaft bores that take years to wear down to the useless point, just an example. If it just up and broke you can probably fix it with rebuilding, it will just take serious effort and paying close attention to even the tiniest detail. Maybe you missed something?
Kidd *and you guys thought I didn't know anything* Andersson. :)
"A hundred days to make me older since the last time that I saw your pretty face. A thousand lies to make me colder and I don't think I could look at this the same, but all the miles that seperate disappear now when I remember your face."
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I just re-read this original message.
The symptoms point towards idle solenoid and idle jet. The idle jet(s) have VERY small holes, as do the passages behind them. Easy to miss dirt, just one transparent grain of sand would be enough. (had it happen many times). Takes quite a bit of compressed air blown into the carb throat holes near the butterfly. The spray can air blower isn't too useful although it might get this particular job done. Remove idle jets first. (Not sure if you had one or two).
The idle solenoid is another common culprit for idle and takeoff problems. It needsw to be tightened down properly for it to have good ground contact. They do also break occasionally. Leaving you with the symptoms you describe. Check the wire to it too. When touching teh solenoid terminal with the disconnected wire terminal, you should get a tiny spark and a faint "click" sound. There are two types of solenoids, a jet type and a piston/plunger type. The latter is a bit hard to test, you'd think that it should retract the piston when you feed it power, but it only does that when the piston is pushed in a littlke by hand. Sort of pre-load. That's how it sits in there when it's tightened down in place. Connect power, start pushing the piston in slowly. At one point it will suddenly suck itself in. The jet type has no moving external parts. Don't really remember how to test it. I think you have the piston type.
Jan
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in article buou5k$kp454$ snipped-for-privacy@ID-72729.news.uni-berlin.de, Jan Andersson at snipped-for-privacy@rocketmail.com wrote on 1/22/04 8:36 AM:

Well, after putting in the 30/31 Brosol , and driving it only about 8 miles, the same problem came right back. Car will not hold a proper idle. Stumbles and dies at a take-off from a stoplight. Can't really play with the clutch/gas pedals to maintain a high enough idle, 'cause it's an auto-stick. Called the mechanic and told him that the new carb that he said would fix the problem didn't seem to be any different from the older carb. Needless to say, he was not happy. I'm beginning to think it' not the carb. More info: Plugs, points, cap & rotor are perfect. All vacuum lines seem fine. Timing is right on 7.5 degrees. Dwell is a little high. Idle at 950 degrees (as per Bentley). Compression checks out fine. Any ideas would be appreciated. -Rich
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miles,
to
per
John's right. Carb icing. I was dicking around in my driveway trying to get my new 1600DP running right and playing around with the jetting. With no load on the motor, my pre-heats were taking their time getting hot. So initially, after a few minutes of fast running (choke) she would just load up and die. Being a buggy with a remote air intake, I don't have the ability to draw air from a warm source. No big deal; in the good weather this won't be a problem but I still wanted to run it up a few times to check things out.
So after getting nowhere with different idle jets and carb adjustments, I propped up a portable electric heater to the air cleaner and now she warms up and just purrs. If I was so inclined to drive it in the winter, the pre-heat pipes will get it warm enough eventually. By the way, I am also running an H30/31 and due to the faster velocity over a 34mm carb, it's even more prone to icing.
Do you have some aftermarket cheapo air filter setup? You need a stock one drawing that warm air from the cylinder discharge. The preheat pipes probably need unplugging.
RT
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in article 3P0Qb.1946$P51.1381@clgrps12, Raymond T. Lowe at snipped-for-privacy@telus.net wrote on 1/22/04 7:47 PM:

Raymond & John: Thanks for the help. Sounds good to me. I'm going home to check out how warm the heat risers feel, then reassess from there. Will keep you and the group posted on what I find. Raymond: With hindsight being 20/20, would you rather you had the 34 PICT or the 30/31? Thanks, Rich
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or
Not really. The 30 should provide better torque down lower in the RPM range. I built this buggy for crawling the mountain trails. Mileage, which equates to range, might also be a bit better with the smaller carb. Another reason was the perceived quality issue. I got the impression on the net that the quality of a new H30/31 is superior to that of a new 34.
RT
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Raymond T. Lowe wrote:

If the icing theory does not seem to be the thing, check for intake manifold leaks. If you have DP heads, the manifold rubber boots might be cracked or the manifold can be loose.
I had a bad sealing between the carburettor and manifold after I rebuilt my carb (wery little old junk left from the old gasket). Symptoms were quite similar. After some ok driving it would not idle any more if I did not push/pump the gas from time to time.
--
Olli

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it's carb icing for sure. Missing thermostat, stove pipe, clogged heat risers...
BTW, we have NEW (not rebuilt) GERMAN carbs at
http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=FSK0051
John Aircooled.Net Inc.

1600's
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How cold does it have to be for carb icing. I live in central Florida and am just wondering if I will have to worry about that here during our 2 week long winters.

PICT).
this
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if it gets below 70F, you can have problems with carb icing (especially if it's humid) if you do not have the engine thermostat, heat risers, and stove pipe, operational.
John Aircooled.Net Inc.

up
from
their
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It can happen in surprisingly warm climates too, moisture is a big contributor.
Jan
Shane wrote:

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Used to be common on the old engines in my dad's sawmill. There were some really hot summer days when we had trouble keeping a couple of them from icing. The carb would just start frosting over from the bottom upward. Soon the engine started blubbering and spewing black smoke. About the only way to make it go away was to shut the engine down and hold the throttle wide open for best heat flow up from engine. After stacking some lumber for a half hour or so, we'd try it again and get another hour or so out of it. We had no heat risers so had to jury-rig what we could with slabs of tree bark and baling wire!

last week, has

(although it cleaned up

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experiences as regards

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Hey... another Central Floridian! Nice to see you.
I know, pointlessly OT but that's what I'm here for!!
Kidd "A hundred days to make me older since the last time that I saw your pretty face. A thousand lies to make me colder and I don't think I could look at this the same, but all the miles that seperate disappear now when I remember your face."
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