Technical Fiat cinquecento ignition timing

[Foiling]

Howdy,

Currently I've got a cinquecento 1.1 fire with lpg installed - first gen mixer, basically a carburetor with a couple of adjustments.

After fighting with the car for a couple of months of not running at all, then not running properly, intermediate running and finally running as well as I could with gasoline and lpg, which involved replacing/cleaning anything related to the fuel system, the lpg evaporator, the works.

I'm now trying to get about the same power out of the lpg as a stock 1.1 running on petrol.

I've done the basic steps, like de-smoging (mainly to clean up the air flow into the throttle body), punto 75 throttle with 75 spacer and I've got a 75 cam that I can drop in.

However, while I'm in there, I'd like to explore the possibility of advancing the timing some, since lpg has a higher octane rating, and I use it about 99.9% of the time.

From what I've seen, most people drill out the timing gear on the cam to get a couple of degrees in petrol applications, however I'm a bit more inclined with advancing the whole gear by one tooth.

Would this be feasible, or am I missing something?

 

[dac69er]

Howdy,

Currently I've got a cinquecento 1.1 fire with lpg installed - first gen mixer, basically a carburetor with a couple of adjustments.

After fighting with the car for a couple of months of not running at all, then not running properly, intermediate running and finally running as well as I could with gasoline and lpg, which involved replacing/cleaning anything related to the fuel system, the lpg evaporator, the works.

I'm now trying to get about the same power out of the lpg as a stock 1.1 running on petrol.

I've done the basic steps, like de-smoging (mainly to clean up the air flow into the throttle body), punto 75 throttle with 75 spacer and I've got a 75 cam that I can drop in.

However, while I'm in there, I'd like to explore the possibility of advancing the timing some, since lpg has a higher octane rating, and I use it about 99.9% of the time.

From what I've seen, most people drill out the timing gear on the cam to get a couple of degrees in petrol applications, however I'm a bit more inclined with advancing the whole gear by one tooth.

Would this be feasible, or am I missing something?

Adjusting the cam gear won't change the ignition timing on the 1.1 cinq only the can timing.

The ignition timing would be determined off the crank pulley sensor. Adjusting that will change the ignition timing, but also the fuel injection timing.

You are probably best off with a piggyback ECU of some description.

 

[Foiling]

Adjusting the cam gear won't change the ignition timing on the 1.1 cinq only the can timing.

The ignition timing would be determined off the crank pulley sensor. Adjusting that will change the ignition timing, but also the fuel injection timing.

You are probably best off with a piggyback ECU of some description.

Yeah, I meant the crank gear. The car basically lives on lpg, hence the semi-permanent switch.

 

[dac69er]

You mentioned the metering of the lpg into the engine is via some sort of carburettor setup? If so and you aren't relying on the crank position signal to fire any injectors, then you can adjust the crank pulley to alter your ignition timing without causing any issues.

 

[varesecrazy]

Hi

Early Injection systems that use what is basically a 'stripped out Carb' as a throttle body

Maybe this is what you have?


My understanding of LPG / GPL:

Is that there are inefficiencies... fuel consumption is poor ( people dont care because it is @50% cheaper..)


But Im not sure you can get comparable Power Gas vs Liquid.. ??

 

[Foiling]

You mentioned the metering of the lpg into the engine is via some sort of carburettor setup? If so and you aren't relying on the crank position signal to fire any injectors, then you can adjust the crank pulley to alter your ignition timing without causing any issues.

Non injection lpg is a deceptively simple concept. Liquid lpg goes into a reducer, which turns it into a gas.

something this:

And then the gas goes into the throttle body via whats called a mixxer:

Since the regular injection tower works like a sandwich, this sits between the injector and the throttle body.


Basically it all works via vacuum and you tune it pretty much like a carb.

There's a ball valve on the hose from the reducer into the mixer which is adjusted for the overall amount of gas that the engine gets and then there's what's basically an idle mix screw and a "sensitivity" screw (it's kind of an overall enrichment circuit that comes into play when the car is jostled around).

Hi

Early Injection systems that use what is basically a 'stripped out Carb' as a throttle body

Maybe this is what you have?


My understanding of LPG / GPL:

Is that there are inefficiencies... fuel consumption is poor ( people dont care because it is @50% cheaper..)


But Im not sure you can get comparable Power Gas vs Liquid.. ??

It's an extremely inefficient process, but the overall usually make up for it. I pretty much always drive the car like I stole it and at it's absolute worst, I get about 10l/100km on LPG, which still translates to about 5l/100km of cost versus petrol with some pretty dire driving habits


Here's the thing, I'm not trying to get the same performance from a modified 1.1 on petrol AND gas, what I'm chasing is about the same performance on LPG as a stock 1.1.