General 1970 Fiat 850 Sport Spyder Run Un-leaded Gas?

[Ron Ross]

I have had this car since 1983 when I was a young man. Now it has been in storage since my last rebuild in year 2000. I am trying to find a carburetor for it. Weber 30 DICA. I believe that I will be rebuilding it this time also. Most that I found on the internet were very expensive but also not available. I have purchased a typical rebuild kit. This time if I must, I will clean everything with crushed glass and zinc plate everything. I have the yellow chromate to re-coat the steel parts. If anyone has a carburetor available or knows of one, please let me know. I will be 67 in March and would like to drive it before I let it go.

I understand that the engine head needs to be modified to run un-leaded gas? Does anyone have any information about that? I have, when it was running having a problem with engine overheating. I chased down all the engine plates for air flow (engine skirts that isolate top half from bottom half) and they are now on the car. The radiator has been cleaned I have removed the water thermostat. I have been told it is caused by burning un-leaded gas. Also, that the valve seats need to be changed for the higher temperature. The engine is in like new condition. I rebuilt it myself. I was able to recover from a cracked block with a little help from a friend. Prayer does work. I had no money but purchased at engine sight unseen at a salvage yard near me. It was in a car that caught on fire and the engine was still in the car. When I went to pick up my engine it was all new including the block. The cam cost more than what I paid for the engine.

Carburetor Weber 30 DICM, if anyone knows of a new one. If I am going to re-build mine, I might as well do several and sell them to cover my cost. I saw many listed for $450 to $650 but no one had one. That is very high since a new Weber similar to this one is $100 to $150.

 

[bugsymike]

I have had this car since 1983 when I was a young man. Now it has been in storage since my last rebuild in year 2000. I am trying to find a carburetor for it. Weber 30 DICA. I believe that I will be rebuilding it this time also. Most that I found on the internet were very expensive but also not available. I have purchased a typical rebuild kit. This time if I must, I will clean everything with crushed glass and zinc plate everything. I have the yellow chromate to re-coat the steel parts. If anyone has a carburetor available or knows of one, please let me know. I will be 67 in March and would like to drive it before I let it go.

I understand that the engine head needs to be modified to run un-leaded gas? Does anyone have any information about that? I have, when it was running having a problem with engine overheating. I chased down all the engine plates for air flow (engine skirts that isolate top half from bottom half) and they are now on the car. The radiator has been cleaned I have removed the water thermostat. I have been told it is caused by burning un-leaded gas. Also, that the valve seats need to be changed for the higher temperature. The engine is in like new condition. I rebuilt it myself. I was able to recover from a cracked block with a little help from a friend. Prayer does work. I had no money but purchased at engine sight unseen at a salvage yard near me. It was in a car that caught on fire and the engine was still in the car. When I went to pick up my engine it was all new including the block. The cam cost more than what I paid for the engine.

Carburetor Weber 30 DICM, if anyone knows of a new one. If I am going to re-build mine, I might as well do several and sell them to cover my cost. I saw many listed for $450 to $650 but no one had one. That is very high since a new Weber similar to this one is $100 to $150.

The tetraethyl lead was an anti knock agent to raise the octane rating to reduce pinking but it also had the advantage of lubricating the valve seats.
So running with unleaded fuel, unless hardened valve seats are fitted by a machine shop you can expect excessive wear to valves and seats.
If only running to an occasional show a short distance you may not have a problem, but the higher the mileage and general usage the more it could cause an issue. I did run an old Fiat Uno which should have had leaded fuel on unleaded for around 18 months with no problem apart from having to retard the ignition to stop the "pinking", but it was only a cheap old banger that I used to abuse by letting the wife drive it .
I may be wrong, but I believe Shell were one of the early suppliers of unleaded fuel in this country and there was a complaint from the Police who did high speeds and mileages reporting the excessive wear experienced to the valve seats.
Regarding the "pinking/knocking" some specialists when reworking the cylinder head could improve the combustion chambers to reduce tendency to knock, but I have no knowledge of how effective that is.
Basically newer cars use computer technology to overcome the deficiency of the modern fuels, so older cars liked the leaded fuel so making them run on unleaded compromises them.
Sometime ago I had and old powerboat with a V6 Buick engine (known as a Volvo Penta 150) the engine was shot and boat had been standing since 1982, so I fitted a 2.8 Sofim diesel engine like earlier Ducato engine, I had to fit a new plastic fuel tank and the old galvanised one was full of very stale Five Star petrol along with water and rust. I filtered the fuel and put it in the old Fiat Uno and it went better than it had for years !

 

[mzerega]

I have had this car since 1983 when I was a young man. Now it has been in storage since my last rebuild in year 2000. I am trying to find a carburetor for it. Weber 30 DICA. I believe that I will be rebuilding it this time also. Most that I found on the internet were very expensive but also not available. I have purchased a typical rebuild kit. This time if I must, I will clean everything with crushed glass and zinc plate everything. I have the yellow chromate to re-coat the steel parts. If anyone has a carburetor available or knows of one, please let me know. I will be 67 in March and would like to drive it before I let it go.

I understand that the engine head needs to be modified to run un-leaded gas? Does anyone have any information about that? I have, when it was running having a problem with engine overheating. I chased down all the engine plates for air flow (engine skirts that isolate top half from bottom half) and they are now on the car. The radiator has been cleaned I have removed the water thermostat. I have been told it is caused by burning un-leaded gas. Also, that the valve seats need to be changed for the higher temperature. The engine is in like new condition. I rebuilt it myself. I was able to recover from a cracked block with a little help from a friend. Prayer does work. I had no money but purchased at engine sight unseen at a salvage yard near me. It was in a car that caught on fire and the engine was still in the car. When I went to pick up my engine it was all new including the block. The cam cost more than what I paid for the engine.

Carburetor Weber 30 DICM, if anyone knows of a new one. If I am going to re-build mine, I might as well do several and sell them to cover my cost. I saw many listed for $450 to $650 but no one had one. That is very high since a new Weber similar to this one is $100 to $150.

My understanding: no-lead gasoline is problem for old iron cylinder heads, because the valves seated directly on the iron casting. On the old all-iron heads, no lead gasoline lead to receding valves. This has never been an issue for aluminum heads since they've always had steel seats installed by the manufacturer; it's never been possible to run a valve - for durations required by any OEM - on a bare aluminum head.

 

[timmycm850]

yep. I Understood that all the 903 heads have especially hardened valves after 1971, so not a problem on yours, I would just run it and not worry.

Tim