Setting up electronic dizzy - gas or petrol?

[pfillery]

I am going to fit an electronic Bosch dizzy to my 186. It is gas and petrol but currently the petrol side is running very rough (I have a rebuild kit for the carby ready to fit unless someone can suggest another logical reason gas runs beautifully and petrol won't idle/stalls when revs drop off) but I wondered should I do this repair first or can the electronic dizzy be successfully set up running on gas? It is the standard stromberg carby.

I have not run on petrol for 6 months and probably wouldn't unless I ran out of gas. Some say that you are better off putting an efi manifold on for running gas only but having petrol is a good backup.

How bad is it not running on petrol regularly if on a dual fuel system? In particular reference to seals etc? If I rekit the carby and run petrol infrequently, will this cause issues?

[BigJon]

Fit the electronic distributor. There is nothing to "set up" apart from base ignition timing. This can easily be done while running on gas.

If the engine runs well on gas but not on petrol then you can be confident it is a fueling issue on petrol. Rebuilding the carby will probably help. Not using petrol regularly will cause issues as the fuel in the bowl will go off and gaskets / seals, etc will dry out.

[geodon]

I'm a LPG novice but your carby problem is most likely a vacuum leak leading to a too lean mixture leading to stalling & rough running. It will manifest itself mainly at times of high vacuum i.e. at low revs & esp idle.

It won't affect LPG because the gas is already premixed & it can't get too lean unless (like my RRC a when a 1 inch diam hose fell off!) you have a BIG hole. The fact that it runs OK on gas tells me that is not the case.

Check:

* Inlet Manifold gasket
* carby flange gasket
* (the sneakiest one of the lot!) badly worn throttle spindle.
* any vacuum powered devices eg brake booster

Get a spray can of WD40 etc with a fine nozzle. Spray some down the carby throat when the eng is running ( I'd try idling on LPG = MAX vacuum). The exhaust should go smoky from burning the WD40. Now try to reproduce the smoke by spraying the bits itemised above. If there is a leak it will be sucked in = a smoky exhaust.

Good luck!

[geodon]

Sorry! I forgot: spray the inlet manifold ( cracked?) and any vacuum take-off points & hoses (splits?).

[bee utey]

I'm a LPG novice but your carby problem is most likely a vacuum leak leading to a too lean mixture leading to stalling & rough running. It will manifest itself mainly at times of high vacuum i.e. at low revs & esp idle.

It won't affect LPG because the gas is already premixed & it can't get too lean unless (like my RRC a when a 1 inch diam hose fell off!) you have a BIG hole. The fact that it runs OK on gas tells me that is not the case.

Check:

* Inlet Manifold gasket
* carby flange gasket
* (the sneakiest one of the lot!) badly worn throttle spindle.
* any vacuum powered devices eg brake booster

Get a spray can of WD40 etc with a fine nozzle. Spray some down the carby throat when the eng is running ( I'd try idling on LPG = MAX vacuum). The exhaust should go smoky from burning the WD40. Now try to reproduce the smoke by spraying the bits itemised above. If there is a leak it will be sucked in = a smoky exhaust.

Good luck!

One of the most common faults on single barrell strommies is the top-half-to-bottom-half screws coming undone. They are philips head and easy enough to get at (external). The gasket can also fall apart there, idle mixture passages run through it.

[geodon]

Hey!

BeeUtey that's what happened on my Hemi powered J3 Bedford.

Good one!

[pfillery]

Already checked all the screws and bolts.

How regular is regular enough to run petrol to keep the carby ok? Some say daily, some say weekly, some say daily is bad. I don't want the seals etc to fail again in 3 months, because lets face it gas is the way to run when it's half the price.

[bee utey]

Already checked all the screws and bolts.

How regular is regular enough to run petrol to keep the carby ok? Some say daily, some say weekly, some say daily is bad. I don't want the seals etc to fail again in 3 months, because lets face it gas is the way to run when it's half the price.

Buy and install a carby kit, don't leave it full of petrol overnight, once a week switch to petrol on the open road. The more often you soak the gaskets with petrol the quicker they shrink and fail when run on gas. Your base-to-body gasket is probably split.

[pfillery]

Buy and install a carby kit, don't leave it full of petrol overnight, once a week switch to petrol on the open road. The more often you soak the gaskets with petrol the quicker they shrink and fail when run on gas. Your base-to-body gasket is probably split.

I bought 2 kits just to be on the safe side, plus they were only $8 each at supercrap auto on a sale (old stock I guess) so I figured at $30+ each normally that was worth it to have a spare.

Just need an uninterrupted weekend to pull out, clean, refurbish, reinstall and set up the carby, oh well I can dream can't I. There seem to be a lot of gas places that say the exact opposite - start on petrol, switch to gas after warm up, then when 5 minutes from home switch back to petrol for the next day's start. Obviously this leaves fuel in the bowl for a bit so doesn't sound like the best plan.

I take it my fuel in my tank should be disposed of (or saved as cleaning fluid) as it has been sitting in there for 6 months+? I'd also suppose a new fuel filter cartridge would be good too?

Are there better plugs to run with the electronic dizzy and/or gas? Or just the stock standard recommended plugs for a 186?

[bee utey]

I bought 2 kits just to be on the safe side, plus they were only $8 each at supercrap auto on a sale (old stock I guess) so I figured at $30+ each normally that was worth it to have a spare.

Just need an uninterrupted weekend to pull out, clean, refurbish, reinstall and set up the carby, oh well I can dream can't I. There seem to be a lot of gas places that say the exact opposite - start on petrol, switch to gas after warm up, then when 5 minutes from home switch back to petrol for the next day's start. Obviously this leaves fuel in the bowl for a bit so doesn't sound like the best plan.

I take it my fuel in my tank should be disposed of (or saved as cleaning fluid) as it has been sitting in there for 6 months+? I'd also suppose a new fuel filter cartridge would be good too?

Are there better plugs to run with the electronic dizzy and/or gas? Or just the stock standard recommended plugs for a 186?

Starting on petrol dirties the oil faster, fouls the plugs faster, wastes money on more expensive petrol, and wastes the most beneficial property of gas, namely its clean burning when cold. I have been gas converting for 27 years so have some idea of carby faults.

Your petrol will probably run OK, add about 10 litres of fresh petrol and run it mostly out before you change the plugs to new ones.

The best plugs for gas are 1 heat range colder than standard and gapped about 30% less than stock. For electronic ignition your Bosch recommended plug is WR7DC+ at 0.8mm gap.