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Black Smoke


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#1 Jaffamini

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Posted 11 September 2020 - 08:14 PM

Just changed the head on my 85 mini old one cracked. Bought a second hand head that looked good, lapped in valves cleaned up and refitted. ( Was never really happy with the finish on the smaller valve seating) but fitted it. Starts and runs but puffs out black smoke when refer up and stinks of petrol.tryed adjusting carb but no difference. Compression test [email protected] 113 psi [email protected] 109 psi. Any ideas.

#2 sledgehammer

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Posted 12 September 2020 - 09:27 AM

check the choke mech is free to return the jet to normal running position

 

check needle hasn't been bent
 

check that the dash pot piston can move up / down freely

 

check dash pot damper is working & not jamming somehow

 

check float chamber isn't overfilling & float & valve are ok

 

only takes a bit of dirt under the float valve seat to let it dribble

 

check float vent is clear as a blockage can force fuel thru jet

 

best of luck


Edited by sledgehammer, 12 September 2020 - 09:30 AM.


#3 cal844

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Posted 12 September 2020 - 09:27 AM

Get the emissions set as per requirements for the year of car.

Did you change the valve stem seals?

#4 dyshipfakta

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Posted 14 September 2020 - 09:53 AM

How long has it been layed up without being run? Not just stale juice is it. Give it a run with some fresh fuel and retorque the head and reassess would be my advice.

#5 Jaffamini

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Posted 15 September 2020 - 06:36 PM

Hi I have just changed my head on my 1985 998 engine,old one cracked. Runs a bit lumpy but puffs out black smoke when refer. Make no difference when adjusting fuel mixture. Plugs are black and very wet.any ideas anyone kevin

#6 robert.hedges

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Posted 15 September 2020 - 06:42 PM

Jaffamini I've literally just posted almost the same thing!! Lol

#7 cal844

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Posted 15 September 2020 - 06:46 PM

Was the old head replaced like for like?

Porting, polishing etc will make a difference

#8 sonscar

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Posted 16 September 2020 - 06:35 AM

Choke stuck on?float chamber flooding?Black smoke is usually too much fuel.Steve..

#9 Jaffamini

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Posted 16 September 2020 - 07:03 PM

Hi all. yes replaced head like for like, cleaned everything lapped in valves + new oil seals. Was not really happy with the smaller valves just could not get a shinny finish. Run fine with old head just through out loads of water out exhaust

Thanks for your replay. Kevin

#10 Jaffamini

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Posted 16 September 2020 - 07:19 PM

Hi thanks just got some new fuel to try,put new valve seals on. Been standing 7 years just turned over now and then. Have noticed the fuel valve at the base is a bit sticky when moving it up and down by hand.

Regards kevin.

#11 the.stroker

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Posted 16 September 2020 - 07:26 PM

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