Webber'd 4AGE Running on 2 Cylinders

[Turdinator]

Loud ticking from the pump isn't unusual for a carbi fuel pump. If anything 42mm DCOEs may be little small if the cams are only coming in at 6500RPM. I don't know specifics on 4AGs but if your running a coil thats designed to not use a ballast resistor with said resistor your spark may be too weak.

As everyone says FIX THE VACUME LEAK before checking these other possibilities. Eliminate one thing at a time.

[4agte]

As Ben said fix the vacuum leak, guessing it is on the cylnders that aren't firing.

Are the cylinders firing at all, CAREFULY feel the extractor pipes on non firing cylnders to see if they are warm/hot.

If not firing at all check wether the front carb is getting fuel.

regards
jon

or use a water spray bottle and spray the extractors to see if it evaporates

[normo]

I have a 4age running twin side draft dellorto's and a Jaycar system to run the ignition.
Swap the carbs around and see if you get a problem in the same cylinders.
How have the injector holes been blocked up in the head?
There could be a vacuum leak there..I used nead-it epoxy (still good after 2 years)

[Billzilla]

twin 42's... on a 1.6, poor thing is probably drowning.

Why?
I used to run twin 45's on a 3K in the racing car. The size of the carby throat means little, it's the size of the chokes. We ran 36mm ones.
Indeed, with big chokes it's better to run big throats as the venturi action works better.

[c2888]

Welcome to the world of carburettors, just wait till the planets align, then it'll drive sweet

Seriously, find a good book on weber sidedraughts, read it, and try and understand what circuits are being used for certain throttle openings. From there you can work out which jets may be blocked, I used to get a plugged jet every now and then when i had double dells on my 4ag. Carburettors work on air flow and throttle openings to draw fuel into the combustion chamber. It's testing my memory but there are a number of jets that control fuel up to the 6500 rpm that you are getting everything to come on song.


Rip the offending jet out and give it a blast of compressed air, don't use wire to poke it, the passages are calibrated orrifices (i said orrifices ) Wear eye protection and keep an extinguisher handy.

http://www.tjwakeman.net/TR/WeberDCOEinfo.htm
A great start on understanding you dcoe.


The ones marked 1 and 2, and the ones next to them, because they a dual throats

Heres the jets that you want to pull out and check, use a GOOD screwdriver, if you don't have one, get a GOOD one, because come 5 years later the tops of the brass jets will be so mangled you won't be able to get them out without destroying them. Whats a bit of brass worth? Sit down when you ask

Goodluck with your carbs

Dan

[nb86]

i forgot in my first post...
check the float levels.
if your'e lazy just make sure that the two carbs have the same fuel level with the jet caps off. if your less lazy take the entire top off the carb (it's only 6 screws or something, be careful with the gasket) make sure that with the top turned upside down the float sits parallel to the face of the body. finnally make sure the needle is sliding easily in the seat.

amen to bill's (and a few others theorys), 42's are fine on a mild 4age. providing you are running at least 32mm chokes. 34's would be ideal for street driving. 36's if you are only running it on the track, but you'd need 40 or 45dcoe's then.

[nb86]

Seriously, find a good book on weber downdraughts, read it, and try and understand what circuits are being used for certain throttle openings.
Dan

dcoe downdraught??

only stirring i'm sure it's a typo. + rep for that post. good link.

[c2888]

dcoe downdraught??

only stirring i'm sure it's a typo. + rep for that post. good link.

fuxed it, it's too early on a sunday morning to be writing essays.
now put a avatar up already

Dan

[Ben Wilson]

I was planning on using rubber O-rings with some gasket sealer as i couldnt find anywhere to buy the specific gaskets.

S&D in Braddon will probably have them.

[nb86]

you can get them through autobarn too, just see someone who looks like they know what theyre talking about, as youll have to order them in and most staff don't actually know what they sell. hopefully there is someone...

[75Ta22LT]

Cheers Guys.

Good dose of carbi clean and a whole lotta revvin cleaned it out, she's now firing on all 4 except running like a bag of shit till about 2000rpm. Im gonna clean the jets out this arvo and have a play around with the idle mixture screws (the all the way in then half turn out theory). How do i find out the choke size?? I want this sucker as streetable as possible. Oh, and yeh the fuel pump is a solid state Facet unit, loud little bugger.

[nb86]

choke sizes are marked on the outer lip of the choke tube, remove the air filters and you should be able to see. i'd check the balance of the carbs by sight, then play with the mixtures, then balance again and so forth. it's a literal balancing act. once you have a feel for it though it only takes a few minutes.