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Old 04-10-2007, 15:38   #1 (permalink)
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how to adjust the air/fuel mixture on older carbies

Could some one help. I have an issue with the air/fuel mixture setting on my carby. I have an 1986 Honda Civic and to date was not able to get any assistance from the Honda forums so thought our Ford fans (particularly older generation guys could help).

I have recently resurfaced all of my surfaces on the carby of my 86 civic (unleaded) and replaced all gaskets and seals etc. The surfaces of all mating surfaces were warped. A full rebuild.

I have adjusted the idle mixture screw in 2 and 5/8 turns as the instructions said in the rebuilt kit for initial set up. How do I back it off and to what distance.

Trouble is the engine is now blowing black sooty smoke and power is not the best. Spark plugs are very sotty also. However, the engine is running 150 % better than before the rebuild.

Could someone please advise the correct procedure for adjusting the air/fuel mixture screw.
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Old 04-11-2007, 01:29   #2 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

G'day.

Last things first. In rebuilding the carby did you check the float level? If that is wrong you can get plenty of black smoke at all engine speeds. Get that right first before you head off for the idle system.

As for the idle mixture, realise that in general turning the screw in weakens the mixture. As you've probably found, it is a tapered pin that mates with a corresponding taper in the carby body. I'd recomend that you wind it in carefully until you fell resistance, that is when the taper bottoms out. Then, wind it out say two turns. That should set the mixture reasonably close for idlinmg. Remeber too that this adjustment does not affect engine speeds above idle, where the main jet system comes into play.

If it runs, start to carefully wind out the screw (ie richen the mixture). The engine should either smooth out, or begin to run a bit rough and hunt. Then wind the screw in. You should go past the smooth spot, and the engine will start to falter. Now its getting lean. Wind the screw out again until you find the sweet spot. Then your mixture should be OK.

Oh - and make sure the timing is correct too.

Good luck!
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Old 04-11-2007, 13:02   #3 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

Hello,

As above, and make sure the choke is not staying on.

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Old 04-11-2007, 15:09   #4 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

Agree with 2 previous posts, also go ahead and replace the plugs.
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Old 04-12-2007, 19:07   #5 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

try a honda forum.
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Old 04-13-2007, 18:54   #6 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

Quote:
Originally Posted by RAVEN
try a honda forum.
Shame on you, from a mod, none the less.
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Old 04-15-2007, 06:43   #7 (permalink)
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Re: how to adjust the air/fuel mixture on older carbies

I have posted this on a honda forum but had no replies ...plenty of viewings but I guess honda people are not tinkerers like us ford guys.
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