23 replies to this topic

[mini-mad-dan]

hi i have a slight misfire/flatspot between 2-3000rmp sings beutifully after and idels o.k if not slighty erraticely, it has coorefct plugs, condensor,dissy, ht, coil, contact rotor arms, and the gaps are spot on, the needle is right (aac) for a 998a+ hs4 (1986) so i assume mixture, but some other help or something simple could be missing( not dashpot that good, assuming 10/w40 is good)

[fikus01]

i wouldnt be suspecting damper oil being a problem, if everything electrical checks out ok then i would be suspecting timing or as u say fuelling
you dont mention CHANGING the coil at any time that could cause the problem, if you are running a ballasted type coil with non ballasted systemyou could be killing the points. the only way round it my be a proper rolling road setup.

p.s. just because the book says a aac needle is for your car they werent perfect by any means, if u have fitted an aftermarked air filter you could be leaning off the mixture between 2- 3000rpm!

[mini-mad-dan]

it has a standerd air filter and the right coil im sure it was identical to the original as the unipart man said it should be! looks like i should have someone with the equipment to tune it then? as im getting it ready for its return to the road!

[1984mini25]

I had a problem similar were the engine would ONLY misfire at 2 –2.5k, turned out the coil was starting to brake down and was overheating.

So you “might” have the wrong coil or its been wired up wrong.

Edited by 1984mini25, 21 December 2006 - 03:24 PM.

[overboost]

Just because the needle is correct, doesnt mean the mixture is correct as well, I would check that, as if its running lean - the engine can develop a flat spot as its not got enough fuel in the mixture, as well as too much fuel can mean the carbs being flooded, although this is less likely to cause any problems.

[mini-mad-dan]

o.k its sorted i was runnig ti for a while and when i turned it off it dieseled so i ran it again richened the mixture and now there is no misfire will check the plugs again after a few miles !

[mini-mad-dan]

right i have set the timeing right witha stroboscopic it was 28 deg out is now set at 8 deg btdc (vac disconnnected) but what does the setting 8+0-2 mean because i have set it at 8 deg, and now it pops and backfires and diesels slightly when i try to turn it off i am assuming it is running lean? or is there a more simple/sinister problem sorry for the questions all the time

[Retro_10s]

you mean it's running on?.... if so... this indicates

*a rich mixture,
*sooted up plugs
*head need sde-coking

[mini-mad-dan]

hmmm i thought that becasue it is running on it was too hot and this was caused by ba lean mixture with a hotter burn thus causing the air/fuel mixture to combust without a spark?
saying this it does pop and seems to be hunting, but when i lean off the mixture even while increasing idle speed it just seems to get worse, can you still buy coulour tune kits?

[Sprocket]

Set the timing first then adjust the fueling to suit. How do you know the fuling is correct??

The 8 +0-2 means that there is a tollerence of ignition timing of + zero degrees and minus 2 degrees, so in practical terms, timing should be between 6 and 8 degrees BTDC.

Having intial ignition timing at 35 degrees or there abouts seems to common these days. Makes me wonder what people are thinking when they leave it like that, especialy when its a Rolling Road operator.

I would have said running on was as a result of an over rich mixture. If your plugs are black and sooty its too rich, if they are sparkly white, then its too rich. A nice pinky brown colour is ideal.

[Sprocket]

edit, ignore this

what was said here,thats for injections, Doh!

Edited by Mini Sprocket, 28 December 2006 - 06:36 PM.

[mini-mad-dan]

it is set to 8 degress as stated earlier and all i can see it being is mixture, so i should keep trying to set it up right then? is there a set measurement with the carb off for inital setting of the jet? as it is sorn ect so i cannot get it to a rolling road!

[Jimmyarm]

Double check your points as well, its better to do it with a Dwell gauge as this will take into account any wear on the lobe in the dizzy

You can get a multimeter from maplins for about £25 that has one, as well as all the usual multimeter functions...

[Retro_10s]

just saw question,.... yes you can still buy the 'Gunsons Colortune'

[mini-mad-dan]

i dunno was wondering about coulourtune, also i ahve a multimeter already, but what do i use to measure the dwell angle? (never done this before)