Twin Webers

Frederick Stienheld · petrol head Joined: 05 Sep 2002 Posts: 2719

I have recently put twin 40IDF webers on my G180 as well as extractors, 2inch exhaust & a mild cam. The performance increase was almost nil. Has anyone else put twin webers on their gemini and could tell me if there was any tricks to getting them to go good?

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

dyno time, tuning and jetting and reputable weber shop,

cheers

Frederick Stienheld · petrol head Joined: 05 Sep 2002 Posts: 2719

Apparently they were dyno tuned when I got them put on, but they seem to have done a rather shocking job. They said it had 75hp. Also I have pulled the spark plugs out since and 2 of them are black and 2 of them are white so perhaps sorting the webers out better would make a decent difference. Maybe I need a better dyno tuning place also
Thanks mate.

CyBeR GeM · tinkerer Joined: 03 Aug 2002 Posts: 181

maybe there is too much or too less fuel being passed to the motor. too much fuel and the engine may not be able to burn it.

Soop · backyard mechanic Joined: 30 May 2002 Posts: 748

Generally when there is too much fuel going through the plugs get wet and get fouled up in black crap.

I say get them tuned Smile

edgie · tinkerer Joined: 05 Aug 2002 Posts: 107

maybe they are runnin differant mixtures?
black sounds too rich and white should be fairly
good to too lean depending how white they r

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

with the webers,

Possible problems IF you webers have been dyno tuned for an 1800 with a mild cam. if not then ignore the below and get them dyno tuned and jetted to suit your motor

1 Webers are not balanced, ie one carbi is opening before the other, (NOT GOOD) would be possible if the rich \ lean plugs are in pairs if 1&2 and 3&4

2, if opposite is 1&3 and 2&4, or 1&4 and 2&3 then someone has played with your 4 mixture screws,

so the black plugs the mixture screw's are too rich (to far out)

a rough way to set them is count the turns it takes to wind them in and record this. , ie 1st takes 2 turns 2nd may take 3 turns .....

for a start:

then pick the average, ie. 2 1/2 turns, set all mixture screws to that, start it up see how it runs, then go from their but keep them together,

cheers
Eggy

CuGem · backyard mechanic Joined: 07 Oct 2001 Posts: 599

if Eggy's suggestions don't sort you out, go see Iain Stewart at Carbtech at Kippa Ring.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

When you were on the dyno to tune your webbers and get the air/fuel mixture correct, what was the horsepower output?

Ben Wight

Frederick Stienheld · petrol head Joined: 05 Sep 2002 Posts: 2719

I have heard that Ian Stewart is the man to see but he is away for a couple of weeks, so when he gets back I will get him to look at them I think

Frederick Stienheld · petrol head Joined: 05 Sep 2002 Posts: 2719

I think your 1. scenario is whats goin on. the 2 front pots are black and the 2 back ones are white. So how bad is it if once carby is opening up before the other? Obviously I am losing performance but is it bad for the engine to drive it until I get it fixed ?

Frederick Stienheld · petrol head Joined: 05 Sep 2002 Posts: 2719

Only 75 Horsepower

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

OK then, long post, enjoy.

solution 1
balancing webers.

get yourself a plastic jar lid that fits nicely over the bell mouths of the webers. so that it will always sit on the same place. ( very important). then get some small hose you can fit in your ear, ( Vacume hose / washer bottle hole) drill holes around the outside of the jar lid and one in the centre just smaller than the hole you have choosen, glue the hose in the centre hole. Now you have made a stethiscope for tuning your webers.

Step one.

listen to the sound of the carbi's seperately, ie cylinder 2 & 3, OK. the webers have seperate idle screw's so step one is get the idle right.

while listening the louder cylinder is the one that is most open. so adjust the the idle screw down a little for that carbi.

once the idle is balanced.

adjust your accelerator cable or put some thing under the accelerator to bring your RPM up to about 3000 rpm. Then listen again. this time adjust the the linkage until both sounds the same, then adjust the engine RPM to check that this is still correct.

then take for a drive and see how it goes, check your plugs,

Solution 2

get it tuned on a dyno.

cheers
Eggy

InSoMnIAC · newbie Joined: 07 Sep 2002 Posts: 8

the problem with one set of plugs sooty and one set white deposits indicates that the carby's are not in tune on is too rich being black and sooty and the other is too lean meaning the plugs are burning. You need to get the two cabys perfectly matched, best way is if the carbies are old check to see if the first few didgits of the serial numbers are the same as if they are not you may never get the carbies working together. then take the car to a better workshop and get the car re-tuned