hi everyone, i think the mixture on my carb is completely offset. the car idles really lumpy and the revs drop to zero when i put my foot onthe clutch after ive been drivin and cuts out.

does this sound like it could not be running rich enough?

does anyone know the correct adjustment for the mixture screw. its a 1987 1.7



cheers

matt

hi

I'm at work at the mo but a word of caution on the 1.7 (also in posted on this site with some good diagrams). The 1.7 carb has a plastic float which over time degrades and does have the buoyancy it should. This affects the level in the float chamber making the car run rich but importantly, makes adjusting the carb to resolve a rich mixture impossible... a new float is needed.

Im not saying that is your problem but if you are having a time getting it to lean out correctly then this might be the cause.

there are some posts here on float height

Pettaw and Chris C are pretty well versed on this so hopefully they'll be along later to advise.

I'll try to find that float thread later...I think it was Wouter who posted some pics testing buoyancy and Jtbo who posted about having a time adjusting the mixture..

good luck!

tried to find that post regarding the floats... no luck yet nut I know it's on this site somewhere.....

thanks alot, i have read the posts about the floats.

the reason i think its not the floats is the guy who had it before me had float trouble, he replaced the whole carb and said he tested the floats and they were good, ive owned it about 3 months now and its only ever bogged down on a hard right hand bend once. so i dont think its the floats, surely it would have happened more than the once if the floats are not working correctly.

did the guy before fit a replacement carb ie a second hand solex or was it a brand new carb? If you're running rich and cant lean it out, then the float maybe ages ie absorbed petrol-degraded and now not having the right buoyancy.

Might be worth coming over to Manc to my friend Howard - a volvo specialist. He and another guy at his garage trained at volvo in the 70s and know the 340 well an everything since too!). He could try to tune it for you

I'll pm you his number if you want

have you checked the CO at the moment ie rich or lean? you'd want to ensure the mix was right as when it'sout it causes lot of symptoms, rough running, poor idle etc. The base plate of these carbs can warp giving air leaks plus the inlet manifold seals seem more prone to fail than the 360s and 1.4s. Checking for leaks with an unlit blowlamp (you need quite a strong flow though) is also a good idea.

continues here....

http://www.volvo300mania.com/forum-uk/v ... php?t=6375

continues here..............


http://www.volvo300mania.com/forum-uk/v ... php?t=6375

Matt, is the carb a solex or weber replacement? Mixture should really be set on a gas tester, your local MOT place if friendly might let you do it over lunch time. This really is the only proper way to do it.

A nearly as good way is a colourtune, hellfrauds sell them, they are pretty damn cool.

If you can't get to a tester, then a quick and dirty way, that will see you ok, is this:

*Airbox on, else the air will be more freeflowing than it should be.
*Twiddle the mixture until the car sounds best, lotsty turns both ways, if you hear birds chirping, stop, that is bad, and go the other way
*Turn the idle to 850
*Twiddle mixture until is sounds bestest again, then screw it half a turn (erm.. now was that in or out, which ever way leans it up, I reckon in... check that)
*Check revs

Car will now be a happy little thing if everything else is working!

thanks for the help guys. its a solex replacement. it was secondhand so may still be the floats i guess.

i tried adjusting the idle mixture all the way in then 2 full turns back. thats what ive been told but im not sure if the idle screw has fallen out. its not a very positive turn when i put the screwdriver in.

im gonna check it out now with a torch down the hole.

nice one

yup full in and then approx 1.5 - 2 turns out is a basic setting to get the car started only.

Chris_C's method is the one you should use once you've got the car running. But don't just screw the thingy in half a turn, you need to slowly screw it until you just hear the revs drop.