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, Tue, 03 Oct 2000 07:55:05
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Oh, I believe it, all right! It's all too typical of the stuff that happens when you try to revive a car - you think you've covered everything, and then, bam!
I'm guessing about all this, since there are a lot of minor variations in Sonett carb plumbing, and a real expert may have more/better guesses... but these will get you started...
-- That square-thing-that-leaks is the accelerator pump. Its job is to squirt extra gas down the carb throat when you stomp on the pedal, so the engine doesn't stumble. Inside that square housing is a rubber diaphragm that does the actual squirting, when pushed by a pushrod that's operated by a little pivoted lever you can probably see on the outside of the housing. What's probably happened to yours is that the rubber diaphragm has torn, so it doesn't squirt anymore and also lets gas leak out.
You can replace the diaphragm without removing the carb (usually) by removing the four screws and taking off the cover. The diaphragm may be hard to find for a Saab, but I think the 1600cc Capri/Pinto engine used the same carb and you might have better luck finding it that way. BUT...
From this it sounds as if your car still has the original FoMoCo carburetor. Consensus is that there's nothing wrong with this carb as long as it's working -- but once it goes bad, it's not worth fixing. The easiest "fix" for any FoMoCo carb problem is to unbolt it, turn it into a doorstop or unusual planter, and bolt on a Weber 34ICH carburetor as a replacement. The Weber fits your stock manifold without modification, although it requires a little fiddling with the throttle linkage. (There are cheaper places on the Internet to get a generic Weber 34ICH, but if you buy it from a Saab specialist -- see classifieds elsewhere on this site -- you'll get advice on how to make the linkage work and also some help with jetting, which is important if you want the engine to run smoothly.) You'll also need to install a manual choke cable as the Weber's choke is not automatic like the FoMoCo's... but the manual is actually more reliable and cleans up the plumbing a bit by eliminating the hoses to the choke heater. You can use your stock air cleaner on the Weber by adding some sheet-metal tabs on the bottom of it and clamping them around the carb's air inlet with a big hose clamp. All this will probably wind up costing you around $200, but most people feel it's money well spent compared to struggling with the FoMoCo.
-- The round-device-with-hoses is the vacuum advance chamber on your distributor. You probably already know that the distributor determines spart timing (what time the time the sparkplug fires as the engine turns) and this is what you adjust with a timing light. The distributor varies the timing automatically depending on engine speed, via a centrifugal gizmo inside it; it also varies the timing depending on engine LOAD, and this is what the round thing and hoses do. The vacuum (amount of "suck") from the carburetor is an indication of engine load, so the round chamber varies the timing by moving the advance plate inside the distributor depending on the degree to which your engine sucks, if you'll pardon the expression.
If those hoses ARE leaky, you should replace them because otherwise they'll let extra air leak into the carb, which throws off your fuel/air mix and makes the engine run rough. They're cheap to fix -- you can just buy vacuum hose of the correct inside diameter at an auto parts store, cut it to length, and replace them.
If you do replace the FoMoCo carb with a Weber, you'll run into a slight quandary because the Weber has only a single vacuum port, while you've got two hoses (most Sonett distributors needed only a single vacuum hose; your "dual chamber" distributor was a short-term solution to meeting 1973 emissions standards.) Again, if you buy from a Saab specialist, he can tell you how to hook up the two hoses to the one port on the carb; my car (1974) had a single-chamber distributor so I didn't need to worry about this. If all else fails you could just try it with either hose hooked up to the carb, see which arrangement makes it run better, and then cap the unused port on the distributor with a rubber cap.
Isn't this fun? By the way, congratulations on your pipe door fix -- it's figuring out this kind of thing and having it work that makes this game enjoyable!
, Tue, 03 Oct 2000 07:55:05, Tue, 03 Oct 2000 14:48:50
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