I have a Topolino A that has been stalling out completely after about 10 minutes of driving. It just dies after a few sputters. I replaced the coil and did a thorough cleaning of the carb. I gave it a shot of starting fluid the last time it did this and it catches until that fluid is used up and then is dead again. I towed the car home and it will start up again by the time I've towed it home. It is clearly a fuel issue. I believe it's vapor lock as it seemed to begin in the summertime and I didn't have the problem when driving in colder weather. Has anyone dealt with this on these cars? The fuel feed is gravity and the carb is on the same side as the exhaust manifold so a lot of heat builds up near the car and fuel lines. Any suggestions on a remedy?
Technical Topolino A fuel issue--possibly vapor lock
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Technical Topolino A fuel issue--possibly vapor lock
Not specific details on your model, but does your carb have a "tufnol" or similar insulating block between carb and manifold?
They often get left off when engine rebuilt. A clue is longer threads on carb mounting studs.
Normally there would be a gasket then the "tufnol" insulating block then another gasket.
When I was an apprentice late 1960s many carbs on older vehicles had that arrangement.
Again as not familiar, but does your fuel tank locate in or near the engine compartment absorbing heat?
Other than that, if pipe disconnected from carb is there a good fuel flow from tank?
Hi bugsymike, There is no spacer between the carb and manifold other than a thin paper gasket. There is about a quarter inch of space I could probably fit a spacer in between. I took a look at other engines on the internet and they don't seem to have any spacers on them. The fuel tank sits behind the engine compartment but is separated by a sheet metal wall. There is good fuel flow to the carb but being that it's gravity feed, I don't know if going uphill impedes that flow. It wasn't until the warm weather came that this problem manifested. Here's a photo of the partially dismantled carb sitting on the manifold just to point out how much space is available.
If you suspect the problem is vapour lock I would be tempted to fit as thick an insulator/"tufnol" block as will go in place but leaving enough room for nuts and locking washers.
You may get a 3/16ths one in there.
Out of interest after a run you could feel how warm the fuel bowl is, or if safe to do so without getting it in the wrong places, next time it plays up tip some cold water around it , or even try one of those freeze spray aerosols as that should not hurt any thing else, it's probably only CO2 .
If it starts and runs straight away that would be fairly conclusive.
Incidentally how warm does the engine run it's self?
I assume it is a side valve model and early cooling was not ultra efficient.
Is it more likely on hills or level roads as well?
I would have thought unlikely to be caused by hills, from memory there are one or two in Italy
Sorry, got side-tracked and didn't get back on here when I should have. The engine can get towards the hot side in the summer. The cooling is very inefficient with no water pump. I would guess that it is happening more on hills, which are all around me where I live. I did not have the problem in the cooler weather which leads me to believe it's vapor lock. It is a side valve flat head. I'll try putting the spacer after the carb and maybe isolate the fuel lines better from the hot engine/manifold.If you suspect the problem is vapour lock I would be tempted to fit as thick an insulator/"tufnol" block as will go in place but leaving enough room for nuts and locking washers.
You may get a 3/16ths one in there.
Out of interest after a run you could feel how warm the fuel bowl is, or if safe to do so without getting it in the wrong places, next time it plays up tip some cold water around it , or even try one of those freeze spray aerosols as that should not hurt any thing else, it's probably only CO2 .
If it starts and runs straight away that would be fairly conclusive.
Incidentally how warm does the engine run it's self?
I assume it is a side valve model and early cooling was not ultra efficient.
Is it more likely on hills or level roads as well?
I would have thought unlikely to be caused by hills, from memory there are one or two in Italy
If running hot is a major problem where you live , then maybe a modern efficient radiator core in your original design radiator.
Another idea is an electric water pump and or an electric radiator fan.
The radiator core idea may look more "original" than the other solutions, it depends which route you choose.