Glow to Petrol Conversion.

[Steve Hargreaves - Moderator]

Thats interesting Tony I didn't know that.......I have to say that the plugs that come out of my wifes Focus are usually a nice light grey colour.....

 

My memories of plug colouration come from my days of two stroke motorbikes & doing a "plug chop".....after fitting some K&N filters to yer RD400 & tweaking the main jet sizes upwards you'd do a high speed run down the local bypass to put the motor under some load then hit the kill switch & whip the clutch in. You'd coast to a halt in a handy layby & take the plugs out......black & sooty meant too rich......white was too lean......light grey/brown & you were just about there

 

Mind you if it was much too lean the piston melted before you got a chance to kill the motor .....the plugs were usually coated in alluminium after that!!!!

 

I suspect Gerald is the man to help here.....he's done a successful conversion after all.....a quick email to Brian Wich might help too.....

Edited By Steve Hargreaves on 25/04/2010 22:04:34

[Gerry Stansfield]

Duog,

what sort of problems are you having with engine? GERRY.

[Ultymate]

Posted by Tony Prince on 25/04/2010 16:35:03:
I'm under correction here, but with full size engines, unleaded doesn't give a nice colouration. it always burns black! The omly way to get an indication is to use a gas analyzer.

 Tony that is absolutely not so, visual plug examination is still a very accurate way of reading mixture settings, unleaded fuel or not whatever the engine full size or model  injection or carburettor. 

[Klippy]

Hi Ultymate, I wonder if the Oil companies are being less than honest about what's in their petrol. My P6 Rover V8 did the last half of its life on, 1 tank leaded, 3 tanks unleaded. On leaded it ran dove grey, on unleaded it was black as yer at! I currently have 3 fuel injected vehicles, they all run black.

[Ultymate]

I run a supercharged injected petrol Merc and the plugs are always a lovely tan colour as are the plugs in my petrol models my petrol strimmer and chainsaws. I have an old Briggs and Stratton lawnmower 4 stroke which needs a lead replacement additive and that too runs a normal plug colour 

[Klippy]

My apologies, Ultymate, my plugs run tan (I took one out) my exhausts run black.

[kiwi g]

Hi Tony

Unleaded runs black in the pipe because of the additives  if Im correct. but leaded runs a nice grey pipe if the car is tuned correctly.

At the plugs because of the combustion temp. they both should be grey altho leaded should be lighter. . Then again I have been proven wrong before

[Steve Hargreaves - Moderator]

The exhaust tailpipe will nearly always be black because most cars don't run for long enough to "burn off" the soot from the rich start up mixture!!!!!

 

I fear we are getting slightly off topic here.....Doug hows that fresh fuel coming along!!!!???

[Ultymate]

Tailpipe colour is usually a function of how hard the car is being driven to get the tailpipes on my Merc a light grey colour means taking liberties with my license 

[Doug Ireland]

Hi steve,

 

No progress since my last post, work got in the way again. I have to go and dig some oil out of the desert in Tunisia for a couple of weeks so the engine will have to wait a bit.

[Steve Hargreaves - Moderator]

Ah...work!!!

 

The curse of the Flying Classes!!!

 

You need a nice little electric model to take away with you.......

[Doug Ireland]

Knowing my luck it would get eaten by a Camel!

[john Wilson 1]

I have converted an ASP 91 4-stroke using the Just Engines CDI box. I am using 20/1 petrol/synthetic. When I run it on the bench or in a model without a cowl it is fine apart from very sensitive needle settings. It gives about 300 revs more on a 14x6 than when run on methanol and ticks over reliably at around 1900rpm. With the cowling on it develops a severe misfire after a couple of minutes running. I think this is due to an overheating problem.

 

I had to lean out both main and idle needles a fair bit. I also abandoned tank pressure, with no ill effects, when the tube melted at the silencer.

 

After a couple of hours on petroil (the engine, not me) I stripped the motor completely and found no signs whatsoever of excessive wear.

 

I have a feeling that the misfire is due to a vapour lock caused by too much heat at the rear of the cowling, but I haven't yet found a cure, other than leaving the cowl off.

 

 

[Klippy]

Hi John, can I suggest you try and get back to pressurising the tank. Perhaps use some of the insulation from noodle wire up at the silencer end. At my altitude (4500ft) petrol vaporises at 40 deg C. Any kind of negative pressure in the pipe = instant vapour lock. Another thing, check that you have at least twice the exit over inlet area for air at the back of the cowl.

[Ultymate]

Using exhaust pressure on a petrol motor is a no-no, high risk of fire

[john Wilson 1]

I'm at only 21m altitude (from the med) so I don't think lack of atmospheric pressure is an issue, irrespective of any possible fire risk. I have, currently, almost 3 times the entry area as cowl exit - ain't that simple - I reckon there is an area of dead air inside the cowl. Next step will be to open up a small exit where I think the air pocket is, and see if that stirs it up at all.

 

By the way, 'scuse my ignorance but what is noodle wire?

[Gerry Stansfield]

Hi. John

I have converted my ASP 52 4 stroke, and used Just Engines cdi unit, I had the same trouble with mine, cutting when fitting on cowl, I placed one of the fuel tank vent's near the carb intake to balance the pressure and it cured it! The filler pipe is blocked off when filled the main needle is set 3/4 of a turn from closed, [no pressure feed}, and it runs and start's super.no problems.

Gerry. 

p,s.

oil mix 20 to 1.

[Klippy]

John, as Ultymate said, there is a high risk of fire with pressurisation. Noodle wire is the wire with a very soft silicone outer, when you hold it at one end, it flops around like a noodle. Back to the problem, as Gery has suggested, put the tank vent close, or next to the carburettor ventury. Also, make sure you have no high points in the feed pipe, it should go as straight as possible from the tank to the carb.

[gerald stansfield]

Anyone had inteference with kill switches on  ignition circuits with  35 meg's.??

Gerry.