weber 45 DCOE synchronising problem... its doing my head in!

[vibrating_Cake]

Right you should know my engine setup already, twin 45 dcoe on a zetec.

im having problems with synchronising these correctly, i.e.

inlets 1 2 and 3 flow the same, and number 4 flows slightly more.

 

thanx to duttnut we have synchronised these the best possible but on idle they are still rough, well, from the exhaust the puffpuffpuffpuff is very smooth and runs about the same, no missing spitting or anything. but on idle the engine wobbles the car!!!!

its doing my head in!!!!

 

how do you ajust the flow between inlets on the same carb body???

i dont have "air bypass screws" on the carbs, which im guessing i'd need lol????????

 

ta in advance

[petrolhead]

Hello Cake,

 

Sounds to me like you may have a twisted throttle shaft. Have you got a pedal stop for the accelerator? The butterflys on a carb should open up at the same time. Sometimes when a throttle stop isn't fitted foot pressure can easily twist the spindle at WOT.

 

Take the filters off and use a mirror and torch to look down the carbs. Get a friend to open up the throttle with the engine off. If one is slightly more 'open' than the other I think you will have to rebuild that carb or replace.

 

If all is OK then it is probably your enrichment screws. Have them a turn out to start off with. Pull the ignition leads one at a time and see if each one makes a difference to the idle. The one that makes the least difference probably needs enriching so unscrew quarter to half a turn.

 

From memory you shouldn't have to go more than 1 3/4 out. This should get you in the ball park

 

Hope this helps,

 

Petrolhead matt

[vibrating_Cake]

no, no pedal stop on the accelerator, but i setup the cable on the carbs so it JUST fully opens the carbs when the pedal is touching the floor, so i doubt its me thats bent them that way.

 

would one be slightly more open if i sat the car and took pictures down the trumpets???

would that be an easier way to look, or would it be better to have them fully open see which one opens more?

[petrolhead]

fair enough, could be bent from the previous owner. I doubt you could tell with the throttle closed if one is slightly more open than the other.

 

I would put your tool box on the throttle pedal and check it at wide open. Its much easier to see a difference when your looking at the butterflys end-on.

[Conor]

 

how do you ajust the flow between inlets on the same carb body???

i dont have "air bypass screws" on the carbs, which im guessing i'd need lol????????

 

ta in advance

 

Unless you're using a carb balancing or flow gauge, you're just pee'ing in the wind anyway.

 

And they will run rough anyway - they're 45's FFS. If you wanted a smooth idle, you should've stuck with injection, a Weber 38DGAS or bike carbs.

 

And my stock Pinto on a 32/36 wobbled on idle and there was nowt wrong with that. Just live with it. A car sat there rocking on idle looks like it's got potential IMO.

[vibrating_Cake]

 

how do you ajust the flow between inlets on the same carb body???

i dont have "air bypass screws" on the carbs, which im guessing i'd need lol????????

 

ta in advance

 

Unless you're using a carb balancing or flow gauge, you're just pee'ing in the wind anyway.

 

And they will run rough anyway - they're 45's FFS. If you wanted a smooth idle, you should've stuck with injection, a Weber 38DGAS or bike carbs.

 

And my stock Pinto on a 32/36 wobbled on idle and there was nowt wrong with that. Just live with it. A car sat there rocking on idle looks like it's got potential IMO.

 

lmao i like your style!!!!!

but..... if you are running 22ftlb of torque in 3 cylinders and 28ftlb of torque in cylinder 4, then cylinder 4 will be under more strain than the other 3, and wear uneaven, maybe its underfuelling or overfuelling?

then itll either pink or coke up, which further makes the car more out of balance!

 

is there any way i can measure the air fuel ration in the cylinders?

 

also yeh it looks the dogs the round ones but this is my daily driver lol =) i gotta do an hour of traffic every mornin!

[Johnson]

what type of linkage have you got??? as my weber one needed adjusting to get the spindles to open at the same time. has this adjuster screw between the carbs been set correctly. my engine did the wobble on idle when my butterflies were out.

 

id recomend balacing the carbs again once the spindles have been set

[SAF_Capri]

if you in the plymouth area, i know a very good home tune man who sorts out any carb problems for me.

[Conor]

also yeh it looks the dogs hairy spheres but this is my daily driver lol =) i gotta do an hour of traffic every mornin!

 

Shouldn't have fitted 45's then is the long and short of it. If they're running with a standard cam, they're gonna overfuel the engine or the airflow into the engine is going to be too low so the fuel doesn't get atomised properly. If you're running a camshaft they're suited for, you're going to have crap low engine speed running and a lumpy idle.

 

This is the thing about carbs. Bolting on the biggest you can find actually knackers performance and driveability if the engine isn't built to need them. 45's are meant for engines that can suck in gobs of air at high speed but those types of engine usually require the car in front of you gets 200 yards up the road before you set off as there's no power in yours until 2000RPM and then all hell breaks loose.

 

There's a long list of peopel who have bolted 45's on to cars only to find that whilst they may sound nice, they go slower and run worse and wallop fuel.

[vibrating_Cake]

also yeh it looks the dogs hairy spheres but this is my daily driver lol =) i gotta do an hour of traffic every mornin!

 

Shouldn't have fitted 45's then is the long and short of it. If they're running with a standard cam, they're gonna overfuel the engine or the airflow into the engine is going to be too low so the fuel doesn't get atomised properly. If you're running a camshaft they're suited for, you're going to have crap low engine speed running and a lumpy idle.

 

This is the thing about carbs. Bolting on the biggest you can find actually knackers performance and driveability if the engine isn't built to need them. 45's are meant for engines that can suck in gobs of air at high speed but those types of engine usually require the car in front of you gets 200 yards up the road before you set off as there's no power in yours until 2000RPM and then all hell breaks loose.

 

There's a long list of peopel who have bolted 45's on to cars only to find that whilst they may sound nice, they go slower and run worse and wallop fuel.

 

read up =o) cam kicks in at 3500rpm till 7000rpm (where the limiter is)

ive got VERY good driveability and can drive around perfectly fine- off cam- 2000rpm is generally the rev range i sit at cause i can put half throttle on and pull away fine.

 

the engine is a 2.0 zetec with ported n polished head cammed and 4-2-1 manifold with 2 inch stainless exhaust right out.

yes the engine can 'bog down' a bit but thats generally anything below 2000rpm when you are being silly with the right foot.

but, you can modulate your right foot right theres plenty of power available, and i think for my spec engine and my driving 30mpg aint half bad!

 

sorry for my rant lol im asking for advice and im not asking for you're opinion when you dont know about the engine.