4ac, Having A Bad Miss

[tas_ae71]

thanks for the ideas

 

had a mate who is a machanic have a look. about a week ago i was fiddling i found that no.3 was the problem cylinder i removed the plug and it was fould, i tryed to clean the contacts on it and put it back in, it went better for abit unil it again fould. it was right for the next few drives then it started miss again, i pulled over and checked no.3 plug and it was clean. continueing on it stard to get worse. he had a fiddle with the points and put a plug from his ge in no.3. we then took it for a drive with it running 98% of the time. returning to his place and using some spray to clean the original plug it was refited and he recomend i get hotter plugs, the same type as his ge uses (1 heat rating hotter). he also said i should add an extra 5 degrees of timing.

[tas_ae71]

is it possible that because i don't currently have a thermostat that because it is running too cold its afecting it? making it miss??

 

i noticed when it was upto operating temp that it seemed to run well but a little further up the road when the temp dropped again it seemed to miss like a barstard again. i have brought a new thermostat, just need to get my thermo fan working again so i can put it in.

[KE30_KE35_KE55]

if this problem happens in cold weather check hot air induction system from air cleaner to exhaust manifold.

 

just put a piece of heat tube from exhaust to the air cleaner inlet, my 4a use to do exactly the same thing.

Edited September 7, 2007 by KE30_KE35_KE55

[irokin]

Have you considered carburettor icing?? With your location I think its a big possibility. I'm not sure how you'd test for it on a car but for aviation ground checks we run the engine up and turn carb heat on. There should be a drop in RPM (due to the less dense hot air) and if theres icing the RPM will then pickup again.

 

You can use this ATSB chart to see if the conditions are right for icing. http://www.atsb.gov.au/pdfs/carb_icing.pdf

[tas_ae71]

don't have a standard air hat, so no turning it to winter mode. what i ment was it seems to run slightly better when the water temp is higher..

 

 

[KE30_KE35_KE55]

don't have a standard air hat, so no turning it to winter mode. what i ment was it seems to run slightly better when the water temp is higher..

 

 

 

to eliminate carby iceing as the problem i would get a roll of aliminium foil as used in the kitchen. wrap it around the carby under the exhaust manifold don't short out any wires, don't leave it like it as it could start burning pipes ect just test drive and see if it makes a difference.

[tas_ae71]

I'm 99.99999% sure it wouldnt be the carb icing because i have driven when the car was under a 1cm of ice an upto the snow... does it during the day too.

 

being the design that the 4ac is, the exhaust being bolted to the intake manifold i belive this would keep some sort of heat in the carb.

 

other people don't have this rpobelm, when i have borrowed a mates t-18 is hasnt had a problem. I'm hoping that this new ignition will fix the problem but I'm worried that its a damaged/worn ring.

[KE30_KE35_KE55]

I'm 99.99999% sure it wouldnt be the carb icing because i have driven when the car was under a 1cm of ice an upto the snow... does it during the day too.

 

being the design that the 4ac is, the exhaust being bolted to the intake manifold i belive this would keep some sort of heat in the carb.

 

other people don't have this rpobelm, when i have borrowed a mates t-18 is hasnt had a problem. I'm hoping that this new ignition will fix the problem but I'm worried that its a damaged/worn ring.

 

Did the new electronic ignition help ?

I looked at a car the other day that was hard to start & spark breaking down after about 10 min, The owner had recently fitted a sports coil the brackert was loose so he rapped about 20 turns of insulation tape around the coil. the secondary on earth side had to jump 4mm between the coil to earth before it jumped the plug gap.

I made a metel spacer and fitted run a dream after that.

[tas_ae71]

yeah mate its been fairly good up until the past few days. when i put i in it instantly was better, the stronger spark is burning almost all the fuel (except on idle).

 

i think my oil is farked because there are some strange sounding noises like the oil is shagged and not getting around where it should be due to heavy contamination by fuel. plenty of oil in there just noisy operation so ill change that before any more damage is done.

 

went to get some of that heat sink silicon stuff and the slack bastards where closed. will try and get some today, hopefully that little board thing doesn't fry before hand.

[KE30_KE35_KE55]

I bought a cheap ae82 seca with a 4A from a car yard about 10 years ago. They

thought the engine was shagged. I herd it and thought it may throw a rod before i got home in it.

about a hour after i bought it i found a broken exhaust recirulation butterfly,

I removed the butterfly and did about 100000km before fitting a worked 4AFC.

you might want to check that.

Edited September 17, 2007 by KE30_KE35_KE55

[thomo]

is your car "growing oil"? if your fuel pump has let go, fuel will leak into the sump, thin the oil, giving you rattles, wash your bore, fowl your plugs and miss like a bitch because you have no fuel presure

[tas_ae71]

i changed the oil today, has only done 3500kms since hte last service.

 

i was thinking that it it may of been because it was running so rich that it may of been comtaminated.