Rank: Veteran
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Joined: 2/08/2006(UTC)
Posts: 1,307
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hey yall,
jest wundering whether overheating is the main cause of preignition?
my 308 shows 90celsius, not hot,, and yet has a degree of preignition when i turn her off.??
apart from this she is running real good, i still think she is running rich on fuel, but excellentey on gas.
have tried adjusting mixture screws, but not much seens to change, and yet carby is in reasonable shape.?
any thoughts? welcomed.
cheers
bcb
it was but yesterday, i thought myself a fragment, quivering without rythum in the sphere of life.
now i know i am the sphere, and all of life quivers in rythmic fragments, within me!
kg. |
more than basketcase than a bear!
DOH!!! |
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Rank: Veteran
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Joined: 25/11/2008(UTC)
Posts: 1,496
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yes overheating can cause it, but so does timing, could be to far advanced
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Rank: Member
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Joined: 3/03/2005(UTC) Posts: 287 ![Australia]( "Australia")
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What carbi are you running? If its the rochester? has it still got the electric solanoid on the throtal linkage at the butter flys?
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Rank: Member
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what carb sounds like the butterfly,s are open to far this will cause running on (dieseling)
close the throttle abit, some adjustment on carb and timing should fix it.
pete.
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Rank: Member
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Joined: 13/07/2009(UTC)
Posts: 18
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It may be too Rich and if so itll carbon up inside, now it will pre-ignite and run on after turning off. You need to Decoke it and change to the correct heat range spark plugs. Correct the float level in your Rochester. you may also as well replace the needle and seat and top horn gasket.
Are you using oil? this could also be the cause of your Carbon-up situation.
Fix any Oil usage defects such as Valve Oil Seals or if your blowing smoke on take off, its the rings. Decoke the engine, this can be done by removing the air-cleaner revving it up a little and pouring water down the gullet slowly from a bottle, this cleans the inside of carbon build-up.
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Rank: Member
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Ahh... the old servo mechanics valve grind and decoke job.
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Rank: Veteran
Groups: Moderator, Registered, Veteran
Joined: 2/08/2006(UTC)
Posts: 1,307
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hey thanks ewes blokes,
uumm?
me thinks it might need decoking.? does not blow smoke at all, petrol or gas,, only oil loss is my shoddy job on getting rocker cover gasket sir henry bolties tight,
the rochester could need a good overhaul, but as i will run mostly on gas, not worth spending too much money on it, just wanted to make sure i was not doing too much damage on the big 5litre!!
i mean without even planting it, it is getting 0>100k,s in about 8 sec,s?
this is on flat, and saying ,,,, one missisippi,, 2 missisippi,,4 missisipi,etc untill it hits 100k,s
awesome!!! bring on the camperer race around the mount!!!
this awesome machine can be viewed in the pub forum, under basketcase diaries
incredible,, wait for the side elevations?? whoa!!
will let you all know how the decoking goes.
thanks again
bcb
it was but yesterday, i thought myself a fragment, quivering without rythum in the sphere of life.
now i know i am the sphere, and all of life quivers in rythmic fragments, within me!
kg. |
more than basketcase than a bear!
DOH!!! |
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Rank: Member
Groups: Registered
Joined: 11/07/2009(UTC)
Posts: 90
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yeh, decoke maybe
a big ASSOCIATED cause of preig is A/F ratio. the leaner you get the more effect factors such as timing and CR will come into play
i think you have said you are getting really good fuel ec, so it might be worth looking at the other end of the scale and seeing if you are actually too lean rather than too rich.
sure, do a decoke with some water sprayed down the carb, but before you spend any more money you might want to (have an analyzer) sniff the tailpipe and see exactly where you are on the stoich
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Rank: Veteran
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Joined: 25/11/2008(UTC)
Posts: 1,496
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for steam cleaning the inside of your engine see this page http://holdenpaedia.oldh...ing_Piston_Ring_Grooves: the info your after is near the bottom of the page
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