The Giardiniera is giving me grief with an "on-again, off-again" problem that seems to me carb-related, and would necessitate a long post to describe. It might come to that, but for now I would just welcome comments on the fact that the engine idles at just about the right speed with idle screw completely backed off. I have taken the carb off and cleaned everything, planed the mating face on a slab of glass with emery and cut out a new gasket to ensure there's no air coming in from there. I can see no gap around the butterfly valve, but still it idles happily. This being the original '71 carb, is it possible that enough air comes in from the side, around the butterfly axis/pivot ? Is this known to happen on old carbs ? Any other ideas ? Thanks.
Technical Carb question please
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Technical Carb question please
Excessive wear on the butterfly spindle can cause air to get in and weaken the mixture which might explain why you have to run with the mixture screw right out. Check for side play on the spindle with the throttle part open. I have not refurbished a Giardi carb but I have rebushed the body on a few 500 and 126 carbs and fitted new spindles so they end up like new.
Thanks for that Toshi, the idle is best with the mixture screw 1 and 3/4 turns out, so maybe the air leaking in is just enough to maintain a slow idle. I'm not sure that's enough to create problems higher up in the rev range (?).
I'm also not quite sure the carb body is worth refurbishing, as the top & bottom "ears" on the flange look weakened from it having been replaned a few times...
I suppose you need tiny adjustable reamers, in addition to turning the bushing, and a full complement of new jets and butterfly valve, etc..., to do the job right. Pfffffffffffffffff
I need to check the price of a new carb, I think.
I'm also not quite sure the carb body is worth refurbishing, as the top & bottom "ears" on the flange look weakened from it having been replaned a few times...
I suppose you need tiny adjustable reamers, in addition to turning the bushing, and a full complement of new jets and butterfly valve, etc..., to do the job right. Pfffffffffffffffff
I need to check the price of a new carb, I think.Hey 1 3/4 turns from fully in is just 1/4 of a turn from the normal initial setting and I would think we'll within an acceptable setting range so maybe don't throw the baby out with the bath water just yet.
Yes rebushing is a bit of a model engineering task and you need the right kit.
If the engineers from back in the 50's that designed the original Weber 26 IMB carbs were put on the stand now I think that they would have to own up to a big design fault. The slow running jet is drilled through the side of the mounting flange and weakens it so that side is always the most deformed if over tightened over the years. With the 126 carb, the Weber 28 IMB, the slow running jet is positioned just above the flange so the flange has much more rigidity.
So if the carb body metal has the ductility to bend I thought it would also have the ability to bend back. So I put the body in my big vice and bend them back as much as possible then just finish on a flat abrasive surface so maybe just remove a couple of thou from the edges.
Good gaskets and the Bakelite spacer are important as well.
Yes rebushing is a bit of a model engineering task and you need the right kit.
If the engineers from back in the 50's that designed the original Weber 26 IMB carbs were put on the stand now I think that they would have to own up to a big design fault. The slow running jet is drilled through the side of the mounting flange and weakens it so that side is always the most deformed if over tightened over the years. With the 126 carb, the Weber 28 IMB, the slow running jet is positioned just above the flange so the flange has much more rigidity.
So if the carb body metal has the ductility to bend I thought it would also have the ability to bend back. So I put the body in my big vice and bend them back as much as possible then just finish on a flat abrasive surface so maybe just remove a couple of thou from the edges.
Good gaskets and the Bakelite spacer are important as well.
[continuation] After another 5 miles/1 and a half hour drive home, I' m ready to tell my tale, maybe someone can shed some light.
I've owned and maintained the Gia for 25 years, but this is new to me.
The car starts normally, always very easily, and I'm off for about 15 minutes of happy motoring. As I'm cruising, the engine abruptly dies, and no amount of pumping the throttle or anything else helps till I'm stopped at the side of the road. After no more than a minute of wondering what the heck, I give it some starter, and it starts and idles normally. I'm off again, and after a few seconds (time to get to third or fourth gear), I get the same again. As it becomes apparent that the engine idles fine and the problem only appears on wider throttle settings, I end up driving home on the idle, in any gear up to fourth depending on the terrain, hugging the side of the road, and praying no sleepy truck driver catches up and obliterates me. I've done up to 15 miles like this.
Of this I've made sure: 1) fuel supply from tank to pump AND from pump to carb is normal. 2) when it dies, there's fuel in the float chamber and pressure in the line downstream of the pump. 3) I checked the carb as described in my OP.
The only mod done recently was fitting the Accuspark.
Any idea appreciated !
I've owned and maintained the Gia for 25 years, but this is new to me.
The car starts normally, always very easily, and I'm off for about 15 minutes of happy motoring. As I'm cruising, the engine abruptly dies, and no amount of pumping the throttle or anything else helps till I'm stopped at the side of the road. After no more than a minute of wondering what the heck, I give it some starter, and it starts and idles normally. I'm off again, and after a few seconds (time to get to third or fourth gear), I get the same again. As it becomes apparent that the engine idles fine and the problem only appears on wider throttle settings, I end up driving home on the idle, in any gear up to fourth depending on the terrain, hugging the side of the road, and praying no sleepy truck driver catches up and obliterates me. I've done up to 15 miles like this.
Of this I've made sure: 1) fuel supply from tank to pump AND from pump to carb is normal. 2) when it dies, there's fuel in the float chamber and pressure in the line downstream of the pump. 3) I checked the carb as described in my OP.
The only mod done recently was fitting the Accuspark.
Any idea appreciated !
the hobbler
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Has the problem only occurred since you fitted the "AccuSpark" ignition? If this is the case, try putting the distributor back to 'points' (with a GOOD condenser--possibly the "Swiftune" unit)) and see if the problem returns. If it doesn't, then have a word with "AccuSpark" as it would seem that you have got a duff unit. I would also be tempted, as a separate job, to try a different coil. remember, try ONLY 1 thing at a time! If the problem STILL occurs after all the above, you will have, at least, eliminated the ignition.
I thought I might give the final verdict on this for the benefit of our shared wisdom & experience: What was doing a good job masquerading as a fuel starvation problem was in fact a dud (duff ?) Accuspark. Thanks Hobbler.
Engine dying whenever some throttle was given, but willing to limp home for miles on idle. Back to points, problem solved. My take on this: you get what you pay for.
Engine dying whenever some throttle was given, but willing to limp home for miles on idle. Back to points, problem solved. My take on this: you get what you pay for.
I'm glad you got that sorted.
Clean, accurately adjusted points on an un-worn distributor....
OK, you have to check them maybe every 6,000 miles or more probably at the rate most people cover the kilometers,.....at the start of every season. But is that such a hardship? I don't think any of us buy a Fiat 500 because we like things to be maintenance-free.
