11 replies to this topic

[Disco Dan]

Okay so I discovered the wonderful invention that is colortune. Had to lean the mixture by about four full turns to get a blue flame :/ but when I lifted the lifting pin on carb to check the engine died.

Richer mixture to manual specs so I get a rev blip when lift pin and colortune shows bright yellow.

Lean it off to a blue flame and it dies when I lift piston pin.

Got Mobil one 15-40w multigrade diesel/petrol oil in car and carb plunger. Could that be issue? Oh and fuel is either "91 octane" or "95 octane". I usually use 91 as it's heaps cheaper.

Edited by Disco Dan, 08 September 2014 - 04:08 AM.

[Disco Dan]

Also not sure if relevant but piston compression reading on piston one was 105 lb. I get a little white smoke under heavy acceleration.

[Dusky]

Okay so I discovered the wonderful invention that is colortune. Had to lean the mixture by about four full turns to get a blue flame :/ but when I lifted the lifting pin on carb to check the engine died.

Richer mixture to manual specs so I get a rev blip when lift pin and colortune shows bright yellow.

Lean it off to a blue flame and it dies when I lift piston pin.

Got Mobil one 15-40w multigrade diesel/petrol oil in car and carb plunger. Could that be issue? Oh and fuel is either "91 octane" or "95 octane". I usually use 91 as it's heaps cheaper.

Lighter oil will lean out the mixture on acceleration. Is is your carb needle set to your engine spec?

[KernowCooper]

If your engine breathing a bit this will effect the colour tune settings, disconnect the breather to inlet and blank off does it change ?

[jaydee]

Do another compression test, a difference of more than 10 psi between cylinders is a sing of headgasket fault.

Test ignition timing to be on specified values for the engine with and without vacuum, the most important test being with vacuum disconnected.

Colourtune is pretty much hopeless on tuning a single carb setup, you can set idle mixture to a decent level, but it wont show whether the mixture at higher revs is correct or not because the flame will be blue anyway. Chances are your mixture is lean under load although idle is correct, this can be corrected only by changing carb needle and tests have to be done with a proper gas analyzer.

Colour tune might be on some help to check mixter spread on a twin carbs setup, but thats debatable too.

[Disco Dan]

Have to confess I've not done timing in donkeys years. Even then it was just static as I don't have a strobe.

Needle no idea what sort or number - Does not appear to have any noticeable markings on it. Feels smooth though no ridges etc but it will be ancient.

I'll richen it by one flat for my drive to work tomorrow and see how it goes on the mway.

[KernowCooper]

You have to take the needle out from the slide they are stamped on the top boss.

[carbon]

Dan - does it 'rattle' a bit when using 91 octane? That sounds really low...

[Disco Dan]

Will do, got a needle chart too!

A tad, will put 95 octane in I suppose! What octane do you get in UK?

[KernowCooper]

95 Ron Supermarket stuff and 99Ron super like Shell V Power, for the rich lol.

[cal844]

95 Ron Supermarket stuff and 99Ron super like Shell V Power, for the rich lol.

yup i use 95 Ron, we actually ha to adjust the timing a bit for the supermarket stuff... i may try putting a tank of Vpower through the system to clear it a bit

[Disco Dan]

Put in 95 octane, did not notice any difference ? But heck still need to buy a timing light, do the timing and do the tappets etc etc 

 

Needle - stamped "ADE"  not listed on my needle charts?? Any ideas?