Technical Pls help a new 500F owner 😬

[69Radbourne500F]

Hi all. I'm new here, and new to the fraternity of obsessed 500 classic owners. She is a 650cc (Radbourne tuned), and has an emblem on the dash saying "650cc Nandi Conversion". I think it is an Abarth engine. Pics below.

I am in desperate need of your wisdom on a few problems I'm trying (not successfully) to contend with and hoping someone can lend some pointers. In no particular order:
She lost power a week ago, and each step I've taken seems to have dug a deeper hole.
A week or so ago she was struggling to start. That's been a theme for a while, but the starter motor eventually died (which I replaced with a 1.2kW model from Ricambio). Aside from the fact that the previous wouldn't start at all, the new starter made a big difference so I put it down to the starter rather than engine problems. It was still quirky starting, and seemed to struggle most when she was warm (ie. good enough at first drive for day). When starting got worse a week ago I was able to clutch start her, but then lost power whilst I was driving and then stalled altogether. I was able to, eventually, get her started again but whenever I gave her half or more throttle she died again. Eventually I had to get a tow truck.

On inspection I found a couple of loose hose clamps on the fuel line before and after the filter, and saw that there were bubbles between the fuel pump and carburetor. These seemed less after tightening the clamps, but she was still spluttering. I noticed the fuel filter was only ever half full or less, and there was some sediment in it so I put a new one in, which increased the amount in it whilst running to probably around two thirds.

The next part is where I feel like things went downhill... I wondered if by tightening the clamps I might need to adjust the fuel/air ratios by tinkering with the carburetor (Dellorto FZD 32.28). Sometimes this seemed to produce results, then even a slight change to get it better undid any progress. When I got it to a point where full throttle whilst stationary was best, I took it for a test drive and had the exact same issue. The things I was adjusting were a short spring screw on the top close to where it attaches to the engine, and a long spring screw under it which is actuated when throttling.

I'm stumped at this point. When I took delivery of the vehicle late last year she started more or less perfectly and there was very little oil in the engine bay and a clean rocker cover gasket (cork). Now, there's a decent amount of oil coming from it, and in the bay generally. My fear is the old owner gave it a clean to conceal an underlying issue, though I don't think so given it was running perfectly and the gasket was perfectly oil-free. There's a bit of a high pitch squeaking noise coming from the engine when she is first starting and probably for the first few minutes of driving (when she's able to be driven. I can say for certain, but I feel like this noise might be moreso now compared to when I first took delivery.

One thing I have noticed is that there is a hole in the front of the engine above the timing belt that occasionally spurts small amounts of dark oil through it under acceleration. A mechanic friend said there should be nothing open and that it may be an inspection port that should be closed - but I'm not sure this is accurate because the inside of the nut is unthreaded. In terms of why the oil coming from it is black, I'm unsure because the sump oil is clean (which is full). There's a pic below.

Would appreciate any input, as I feel totally out of my depth! She's supposed to be my daily driver, and I'm infatuated with her! Thanks to anyone who's willing to share any insights.

Jono

 

[Bounding Bambino]

Im going to give my few cents first. Others will chime in.

First off, to know the history of the engine, check out the numbers stamped on the engine case next to the fuel pump It can start with either a 110 or 126.. This will help narrow down if its a original 500 engine or 126 engine. (edit, looked closer at the photo seems to say 110F.) so its a guess what the actual displacement is or what mods have been done without digging in deep. typically a 110f is 499cc in stock form.

Now to your last question. Those bolts are vent holes that are part of the head that allow combustion gas to bypass incase of a head gasket failure. Ideal is its to prevent gasses from going into the cooling air stream, and theoretically into the passenger compartment. consider it a feature instead of a critical component.


So ill quickly give a quick synopsis of what could be the issue. I could go on for ages, but it will help you with beginning troubleshooting.
You either have a fuel delivery, ignition, or compression issue.

Fuel first. I realize that those could possibly be new fuel lines. Thing is, if the originals were used, they are prone to bursting and has taken one a many 500's lives. Just to be sure, replace it with a decent quality rubber fuel hose. Preferably efi rated for extra protection in the hot engine compartment, and use the full band screw clamp style fuel line clamps.
Next. check fuel delivery. Will probably need a 2 person job, but disconnect the feed to the carb, and see how well the pump is pumping. You could have a weak pump not supplying enough or a fuel pressure issue. Its kinda a 2 person job. One to crank, one to watch as you pump it into a empty bottle. After that, then i would start to tackle carb internals.

Also potentially a air leak around the carb base gaskets could also be an issue. Best to check and make sure everything is snug.

Ignition. We would need to know if your car still has point or electronic ignition conversion. If you pop the distributor cover off, you will be able to see if someone kept the original points or upgraded to electronic. Sometimes the electronic system fails due to the high temp environment that the rotor is in (blowing hot engine heat over the whole assembly). From there you can check and see if the system is operating as expected or some parts are needed. These are super simple engines, and points ignitions do need some basic maintenance.

If spark and fuel check out, and your still getting inconsistent running. A quick compression test would be ideal, and also check ignition timing to see if its within spec. A timing light would be ideal for best accuracy. But there are ways to check by just using a troubleshooting light and markings on the engine case.

 

[the hobbler]

Im going to give my few cents first. Others will chime in.

First off, to know the history of the engine, check out the numbers stamped on the engine case next to the fuel pump It can start with either a 110 or 126.. This will help narrow down if its a original 500 engine or 126 engine. (edit, looked closer at the photo seems to say 110F.) so its a guess what the actual displacement is or what mods have been done without digging in deep. typically a 110f is 499cc in stock form.

Now to your last question. Those bolts are vent holes that are part of the head that allow combustion gas to bypass incase of a head gasket failure. Ideal is its to prevent gasses from going into the cooling air stream, and theoretically into the passenger compartment. consider it a feature instead of a critical component.


So ill quickly give a quick synopsis of what could be the issue. I could go on for ages, but it will help you with beginning troubleshooting.
You either have a fuel delivery, ignition, or compression issue.

Fuel first. I realize that those could possibly be new fuel lines. Thing is, if the originals were used, they are prone to bursting and has taken one a many 500's lives. Just to be sure, replace it with a decent quality rubber fuel hose. Preferably efi rated for extra protection in the hot engine compartment, and use the full band screw clamp style fuel line clamps.
Next. check fuel delivery. Will probably need a 2 person job, but disconnect the feed to the carb, and see how well the pump is pumping. You could have a weak pump not supplying enough or a fuel pressure issue. Its kinda a 2 person job. One to crank, one to watch as you pump it into a empty bottle. After that, then i would start to tackle carb internals.

Also potentially a air leak around the carb base gaskets could also be an issue. Best to check and make sure everything is snug.

Ignition. We would need to know if your car still has point or electronic ignition conversion. If you pop the distributor cover off, you will be able to see if someone kept the original points or upgraded to electronic. Sometimes the electronic system fails due to the high temp environment that the rotor is in (blowing hot engine heat over the whole assembly). From there you can check and see if the system is operating as expected or some parts are needed. These are super simple engines, and points ignitions do need some basic maintenance.

If spark and fuel check out, and your still getting inconsistent running. A quick compression test would be ideal, and also check ignition timing to see if its within spec. A timing light would be ideal for best accuracy. But there are ways to check by just using a troubleshooting light and markings on the engine case.

If this is a "Radbourne" car, with a badge saying "Nardi 650 conversion" it is probably NOT an Abarth engine. Radbourne Racing, in London during the late 1960s, converted quite a number of stock 500s using the Nardi 650 barrels (or, to be precise 652cc). They did NOT fit the Dellorto FZD carb, instead just re-jetting the original Weber IMB carb---so this has been fitted subsequantly. You should only be adjusting the short 'spring tensioned' screw at the rear of the engine (idle speed adjustment) and a screw at the top-front of the carb (mixture). The other "long" spring is for the accelerator pump---basically leave it alone! The fact that oil is coming out of that hollow bolt COULD mean that you have a blown head gasket. That bolt is designed to be hollow and lead to a drilling in the head to let out the exhaust fumes when the head gasket does blow---DO NOT BLOCK IT UP. If possible,remove that fuel-filter which is over the dynamo---not a wise place to put a filter. The engine has 3 other filters---fuel pick-up in the tank, top of fuel-pump and top of carb--it is not neccesary, Properly set up, the Dellorto FZD is just about the best carb you can have for a 'road-use-only' car. How do I know this?---I worked at Radbourne Racing as a young mechanic doing the Nardi conversions. If you think that I can be of help, feel free to contact me direct--- [email protected] The suggestions made by Jaques (Bounding Bambino) are well worth takingg into consideration

 

[the hobbler]

If this is a "Radbourne" car, with a badge saying "Nardi 650 conversion" it is probably NOT an Abarth engine. Radbourne Racing, in London during the late 1960s, converted quite a number of stock 500s using the Nardi 650 barrels (or, to be precise 652cc). They did NOT fit the Dellorto FZD carb, instead just re-jetting the original Weber IMB carb---so this has been fitted subsequantly. You should only be adjusting the short 'spring tensioned' screw at the rear of the engine (idle speed adjustment) and a screw at the top-front of the carb (mixture). The other "long" spring is for the accelerator pump---basically leave it alone! The fact that oil is coming out of that hollow bolt COULD mean that you have a blown head gasket. That bolt is designed to be hollow and lead to a drilling in the head to let out the exhaust fumes when the head gasket does blow---DO NOT BLOCK IT UP. If possible,remove that fuel-filter which is over the dynamo---not a wise place to put a filter. The engine has 3 other filters---fuel pick-up in the tank, top of fuel-pump and top of carb--it is not neccesary, Properly set up, the Dellorto FZD is just about the best carb you can have for a 'road-use-only' car. How do I know this?---I worked at Radbourne Racing as a young mechanic doing the Nardi conversions. If you think that I can be of help, feel free to contact me direct--- [email protected] The suggestions made by Jaques (Bounding Bambino) are well worth takingg into consideration

Apologies, a couple of things that I forgot to mention---(1) I have some period road-tests of the Radbourne converted cars and, (2) I have quite a lot of information regarding the FZD carbs. If you would like copies of all this information, contact me direct, let me have a postal address and I will copy it all out for you and post it to you (it is all on that old fashioned thing called---paper)

 

[Toshi 975]

If you have any discharge from those hollow bolts (there is a similar one opposite side of the engine) then it is time to pull the cylinder head to see what is going on. You might want to check the flatness of the head and consider fitting a copper head gasket.
I am pretty sure that the Dellorto FZD carb was not the original fitment when the engine was tuned as the signs are that it was once half of a twin carb set up which is why you have two fuel inlets, deep holes in the throttle and choke spindle nut and bolt which would have accommodated the twin carb linkage. Also the link between the choke and throttle is missing which gives a slight increase in revs when the choke is activated. My guess is also that the throttle and possibly choke return springs are missing as with the twin carb set up the springs are on the linkage. As Tom will tell you the choke is often not needed for starting as you can use the accelerator pump to richen the mixture to fire it up however the choke can come in handy sometimes. I rebuilt a couple of FZDs recently which also had that link missing and I came up with a bolt on solution.

 

[Bleeding Knuckles]

Hi Jono, question, does the exhaust smoke after you leave the car idling for a while and then rev it?? You should not have oil leaking from the gas ring vent. It seems that oil is getting past the piston rings and into the cylinder(s) you may have a blown cylinder head gasket too as Toshi says pull the head off and check!!
Ian.