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ratwell
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Joined: April 26, 2003
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Location: Victoria, BC
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 Posted: Thu Dec 09, 2004 11:14 am Post subject: 34-PDSIT-2/3 rebuild |
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I'm rebuilding my first set of these dual solex carbs and going through the testing procedure two things are puzzling me.
1) The accelerator pump is rated for 0.8-1.0cc. The book says you'll expell 10x that much with 10 quick pumps but the rate I can get is 0.7cc pumping it slowly. What does this indicate? If there anything I can do about it?
2) The spec for the float is 12-14mm from the top of the lower body. There are no leaks and the valve is working correctly but the best I can achieve is 17-18mm. It's not possible to un-shim the float valve to raise the level. Because of the design of the float chamber, bending the float support doesn't seem possible either. Stumped...
Any experts out there?
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'76 Doublecab Sweden
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DurocShark
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Joined: April 05, 2004
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Location: Crappy town in a crappy state. But the beach is nearby, so I have that going for me.
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| Posted: Thu Dec 09, 2004 3:42 pm Post subject: |
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I saw the discussion on the Type2 list too...
Richard, if you need some spare parts let me know. I've got a box of the things. 
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ratwell
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Location: Victoria, BC
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| Posted: Thu Dec 09, 2004 4:13 pm Post subject: |
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| DurocShark wrote: |
| Richard, if you need some spare parts let me know. I've got a box of the things |
I could use the cotter pin and washer that goes on the acc. pump as one is missing on the right carb.
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DurocShark
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| Posted: Thu Dec 09, 2004 4:19 pm Post subject: |
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You got it. PM me your addy and I'll stick it in an envelope.
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ratwell
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Location: Victoria, BC
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Amskeptic
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Joined: October 18, 2002
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Location: All Across The Country
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| Posted: Thu Dec 09, 2004 5:59 pm Post subject: Re: 34-PDSIT-2/3 rebuild |
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| ratwell wrote: |
1) The accelerator pump is rated for 0.8-1.0cc. The book says you'll expell 10x that much with 10 quick pumps but the rate I can get is 0.7cc pumping it slowly. What does this indicate? If there anything I can do about it?
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Chances are you have '73-4 dual carbs that flow at .7cc. The best you can do is to play with the cotter pin adjustment holes to give the pumps a little more time to inject.
| ratwell wrote: |
2) The spec for the float is 12-14mm from the top of the lower body. There are no leaks and the valve is working correctly but the best I can achieve is 17-18mm. It's not possible to un-shim the float valve to raise the level. Because of the design of the float chamber, bending the float support doesn't seem possible either. Stumped...
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These engines are mounted in the chassis at quite an angle. Be careful that you mimic the slope-towards-the-flywheel before you measure the fuel level. No gasket should be on the body of the carb. Just pick a thin .20 washer and try using both the old needle valve and one of the new ones in the kit to see which one gives your best reading.
| ratwell wrote: |
Any experts out there?
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Uh, debatable. . .
Colin
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ratwell
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Joined: April 26, 2003
Posts: 8731
Location: Victoria, BC
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| Posted: Thu Dec 09, 2004 6:24 pm Post subject: Re: 34-PDSIT-2/3 rebuild |
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| Amskeptic wrote: |
| Chances are you have '73-4 dual carbs that flow at .7cc. The best you can do is to play with the cotter pin adjustment holes to give the pumps a little more time to inject. |
I have the part number tabs. I'll have to check them but I'm pretty sure they are 72 models because they lack the temperature cutoff.
| Quote: |
| These engines are mounted in the chassis at quite an angle. Be careful that you mimic the slope-towards-the-flywheel before you measure the fuel level. |
What's the angle? Bentley said to put the body on a level surface for measurement. The bus isn't going to be level all the time while driving...
So far I've goofed up one part of the measurement. In looking up the densities of water and gasoline to compute weight I would need to add to float I completely forgot my original measurement was done with water (999g/l) vs. gasoline (830g/l). I'm going to switch to gasoline and see how much this sinks the float and raises the fluid level. Doh!
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Amskeptic
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| Posted: Thu Dec 09, 2004 6:36 pm Post subject: |
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It is understood by the engineers that the car won't be level much, but the measurement value requires it to dial in the fuel level bell curve average solved for p1 p2/mean.
Hey. Don't put water in the carb 
Colin
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thenexttownshend
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Joined: November 27, 2003
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Location: Rhode Island
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| Posted: Thu Dec 09, 2004 7:03 pm Post subject: |
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Hmm i cant help comparing ratwells detailed rebuilding specifications to my sitting in the drivway with Colin rebuild carbs with napkins and toothbrushes, gumout bath in a recycling bin top, the neighbor cleaning out his work van saying "Hey heres an extra tooth brush you guys can use!"
Good luck ratwell, it really is fun after all isnt it?
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Amskeptic
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| Posted: Thu Dec 09, 2004 7:20 pm Post subject: |
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| thenexttownshend wrote: |
Hmm i cant help comparing ratwells detailed rebuilding specifications to my sitting in the driveway with Colin rebuilding carbs with napkins and toothbrushes in a gumout bath in a recycling bin top, the neighbor cleaning out his work van saying "Hey heres an extra tooth brush you guys can use!"
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I remember that recycling bin lid It *was* green. And how are your carbs working? Did we get the .76652 cc accelerator pump volumes correctly factored for your average median humidity and annual temperature mean at 43 feet elevation for Rhode Island at a barometric pressure of 30.2" divided by your compression pressures over factory spec minus carbon build-up squared divided by pii to the air correction factor of your leaking throttle bushes?
Colin
( Ratwell, the thermostatic accelerator pump outlets came a year after the .7cc stroke pumps. They have an adjustable sleeve to adjust injection quantity)
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Amskeptic
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| Posted: Thu Dec 09, 2004 7:32 pm Post subject: |
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( punch line mysteriously disappeared, leaving this post eerily irrelevant)
12/09/04 11:35PM
lol, you got that right.
Don't even tell Ratwell about the test drive, Steve 
Colin
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Last edited by Amskeptic on Thu Dec 09, 2004 9:33 pm; edited 1 time in total |
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DurocShark
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Location: Crappy town in a crappy state. But the beach is nearby, so I have that going for me.
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| Posted: Thu Dec 09, 2004 9:26 pm Post subject: |
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Richard,
The seal for the main jet screw: It doesn't exist! I took apart 2 separate carbs, one that had obviously been rebuilt in the past (screwdriver marks on some internal screws) and one that obviously had NOT.. All the seals were still on the adjustment screws and such. No seal on either carb for either jet screw. Strange.
I got you everything else, but the screws holding the choke flap are nasty. They don't want to come loose. I stopped after mangling one screw. I'm soaking a couple in oil overnight to see if they loosen enough to come off clean.
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ratwell
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Location: Victoria, BC
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| Posted: Thu Dec 09, 2004 11:09 pm Post subject: |
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| DurocShark wrote: |
The seal for the main jet screw: It doesn't exist
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I think in that diagram there is a seal on the plug. That's what I was looking for. I verified the part number tag: these are 72 carbs.
| Quote: |
| All the seals were still on the adjustment screws and such. No seal on either carb for either jet screw. Strange. |
I've noticed that people have loosely borrowed the diagrams. One book I've been looking at shows the 32 PDSIT carb factory cutaway with no mention it's a different carb (Type 3).
| Quote: |
| I got you everything else, but the screws holding the choke flap are nasty. They don't want to come loose. I stopped after mangling one screw. I'm soaking a couple in oil overnight to see if they loosen enough to come off clean. |
No doubt. I've found you need A1 screwdrivers for working on these things. Lucky I have a set designed for countersunk screws.
I switched to gasoline (PU) bent the tab on the float back to stock and the float level is 16mm. The tab is not adjustable: if you bend the tab the float is so close to the edge of the bowl it hits and the bowl overflows. I don't see the point in verifying the float level with all these restrictions. The only adjustment I can see is in varying the weight. Several sources that talk about float repair caution against it but only in the context of adding UN-necessary weight. Bentley makes no mention.
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