...is this how you mounted it? I know their instructions say to mount it on the coil, but a previous thread highlighted some issues with that, and from what I can gather, this is correct. I'm getting this distributor setup for some further troubleshooting.

After my air dam experiment, there's still a miss @ about 85-90km/h. Better than before, but still present. I can't seem to duplicate it at similar revs at lower speeds, so I'm wondering if there's an airflow issue at speed. It only happens above ~80 km/h and once it starts, if you stay in it, it'll get progressively worse. Once you ease off and get on back roads at varied speeds/revs, all is well again. Tappets are spot on - adjusted before the test run and check afterwards.

It was doing this before on the old motor as well. Carb is completely different now and only the fuel pump remains the same. I'm a little lost here. Ideas?

Does the fuel pump have a filter? could that be partly blocked?
I don't know this engine as it's a long time since i worked on one
if the fuel pump is driven off the camshaft does it have a plunger
like older VW's? is that sticking is ware on the pump or cam limiting stroke?
Could if the pump is mechanical you substitute a electric one as a test.
I suspect the pump is not delivering enough fuel at high loads.

Matt; before you throw the mechanical pump out and spend your hard earned dollars on an electrical pump, may I suggest that you firstly check that the operating pin (for the pump) is correctly 'adjusted'. It is 'adjusted' by removing/adding gaskets adjacent to the spacer. The pin should protrude at the START of its movement 1 to 1.5mm out past the spacer AND all the gaskets. I tend to set it to the maximum protrudence, using the required thickness of feeler gauges across the face of the last gasket. Alternatively, if you can find a strip of steel (or plastic) that is 1.5mm thick, use that across the face of the outermost gasket alongside the pin (does that sound sense?)
As I have said on a number of occasions, the Fiat fuel-pump hardly ever gives a problem, and Abarth used the oroginal mechanical pump on all hei road-going variants---even the 695SS!
One other thought---have you put a one-way valve into the fuel system (to prevent the fuel syphoning itself backto the tank)? I had a one-way/check valve in my system for a time between the pump and the carb---engine went fine. I looked at it and thought "what a stupid place to put it" so moved it to just outside the fuel tank---engine just didn't want to go above about 50mph (80kmh)--and I had a show the next day!. After a bit of thought, I came to the conclusion that the only thing that i had changed was the location of the 'one-way' valve---so removed it; engine returned to its fiery self--phew!!
Conclusion? the Fiat pump will PUSH fuel through a one-way/check valve, but NOT PULL it!

I ordered a cheap little check valve to test that, but I also have a spare, new in the box, fuel pump, so no need to go electric. I suppose I’ll pull it off and check the pump rod lengths, but this only seems to happen at cruise and isn’t apparent at lower speeds and high RPM.

Thoughts on the swiftune?

Thanks.

the hobbler said:

The pin should protrude at the START of its movement 1 to 1.5mm out past the spacer AND all the gaskets.

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That is the case when using an original spec. pump/spacer/gaskets/rod combination. But I have seen that there is a very wide variety of aftermarket designs of pump and its actuating-arm, and at least one of those which I own did not respond to that sort of precision and caused occasional fuel starvation when motoring at a brisk but steady pace.

My solution was to try a different pump where the static position of the arm was closer to the mounting flange; that did work.

I think that might’ve been the problem Peter. I pulled the fuel pump, checked the rod protrusion (all good), and installed my spare pump. The new pump’s lever arm certainly protruded more than the previously installed one. Test drive seems to confirm that was the issue. She was humming along at 100km/h with no issues.

Until the next hiccup...

JumpJet said:

Test drive seems to confirm that was the issue. She was humming along at 100km/h with no issues.

Until the next hiccup...

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So with a bit of luck, that eliminates the location of the condenser as being involved with the issue. I suspect that such a robust item as that should be impervious to being fitted onto the distributor. But given how easy it is to move it about, and seeing that it appears to have a long, integrated lead, I would be experimenting by giving it a try in a reverse position and attach it at or near to the coil for a while.

fiat500 said:

So with a bit of luck, that eliminates the location of the condenser as being involved with the issue. I suspect that such a robust item as that should be impervious to being fitted onto the distributor. But given how easy it is to move it about, and seeing that it appears to have a long, integrated lead, I would be experimenting by giving it a try in a reverse position and attach it at or near to the coil for a while.

Click to expand...

I actually didn't change out the distributor for this test. I left the Pertronix in place. In the end, the 123 could've been a separate issue, but the harsh wear on it and the dead coil weren't helping at all. I plan to leave the hall effect setup in place, so long as it works, but am keeping the points+swiftune setup ready to go as a backup if needed. Being a backup, I'll probably just leave it all together as an all-in-one unit to swap in.

Strangely Matt;I have done exactly the same with my spare "have it in the car in case" distributor, and like you, have left the distributor and condenser as 1 unit. If it has to be fitted as a "longish time fixter" then I will move the Swiftune condenser next to the coil---condensers don't like heat either!
With regard to the fuel pump---and you wonder why i have such a passionte hatred of 'pattern' parts?

the hobbler said:

With regard to the fuel pump---and you wonder why i have such a passionte hatred of 'pattern' parts?

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I don’t know how much hate I can have for the pump, it’s been on the car for quite some time - at least 5 years since
I bought the car in Italy. I think it might’ve just had its time. Hopefully, this replacement pump can hold its own.