twin 40`s help wanted

[Anonymous]

right my probs are this

i have just bought sum twin 40`s off my mates 1.4 astra, there now fitted on my 1.4 nova so i havent played with the mixture settings yet.

the car seams to idle really ruff
the car is fitted with piper 270 highlift cam as well would this make my idle ruff?
the idle wasnt really noticable with the standerd carb and k & n filter.
now its lumpy at low revs although top end reving is smooth

i have played with the timing and the carb balance screw althogh i havent actually managed to get a balance meter on yet as my dads fouls on the bulkhead.

another things is aperntly i havent got a proper throttle linkage
the parst ai was supllied with were home made and crap
i made a new throttle cable/stop bracket and this works ok but when i rev hard the revs take a bit to long to settle again (sumtimes like 10secs or sumthing)
it also spits and pops like fuck after i back off the throttle and it gives the odd spit when idleing

i thought maybe my throttle bracket wasnt letting the throttle close properly and it was jamming open, but a quick bracket made up with a elastic band atached made sure the throttle was being fully closed, and the problem was still there.

anybody got sum ideas?

i will buy the proper cable/throttlelinkage if i can get the carbs to set up properlly ,ie im not spending even more money if there fucked up.
and im also a bit reluctant to give mr rolling road man sum pennies to set it up if sumbody knows whats a matter or there fucked dont bother.

the car actually drives quite smoothly apart from the revs thing

dont gimmie any "have you changed your oil recntly posts as it was running fine 4 hours ago with the 2E3 carb on it

lol
cheers peeps



Micky@novaload.net :)

[Anonymous]

as ur car got a flat spot so basicly is your just cruising along at bout 1 and a half thousand revs then suddenly boot it it just blurs out bot its ok when u get past 2 thousand revs and boot it it dont blur out av u got this prob cause it think it might b the venturis as they are 32mm ones and i think 30mm chokes should be in there

[Anonymous]

Well, the over-rev or wotever u call it i find is often becuz of 2 things!!!
1). The timing needs setting up again (may also explain y idle is lumpy!!)
2).The carbs r sucking too much air on idle. (leak on manifold).

Number 1 is easy to check urself and i cant see y u havent already tried it m8!
Number 2 is a real biatch until u find exactly where the problem is!!!
Hope this helps, d1cko!!!

[Anonymous]

mate mate says your supposed to have proper o rings between carb and manifold and i just used instant gasket

thing is they ran mint on his astra?
i have been on with the timing all fucking day

i think ill try squirting summit around the carbs and manifold 2morrow
ive just got a lend ov a another balancing tool as well
soi will see how i go 2morrow

if there still not right by thursday im taking them off and selling em coz i cant be botherd with fixing 2 cars at the moment

Micky@novaload.net :)

[Anonymous]

Micky, if the stuff I told you earlier sorts it, leave a post for me so I know. You shouldnt have any problems if you follow what I said, but if you still want to sell it all I`ll buy em off ya!

good luck mate and dont hesitate to call, coz I know weber 40`s very well now.

And yes 32mm chokes are far too big, you need 30 at biggest on a 1.4 and even on a 1.6 30 would still be fine. Main jet should be around 120, air 190/180ish. THe larger the main the more fuel accross the whole range, and the smaller the air, the more fuel you get at higher rpm/throttle.

[Anonymous]

ok cheers ill have a play

Micky@novaload.net :)

[Anonymous]

right i think i ve narrowed it down

i checked the crabs yesterday to see if there were sucking in air from the carb to manifold join
they wernt

but as i spent the day tring to balnce them etc etc they seam to have devolped loads ov leaks

so is i balanced them and fettled they were fucking up more and more

lol
anyways i have ordered the mounting blocks and O rings from the nice man at demon tweeks
they should be here in a few days

ill give it a whirl again then

should be ok though cheers

Micky@novaload.net :)

[Anonymous]

The proper "O" ring kit is mainly for damping vibration to stop fuel frothing problems.
Spitting and popping out the carbs on decelleration is excess/loose unburnt fuel kicking about in the inlet tracts etc.
As other have said you need the right venturis in as a matter of priority. It could be that the draw from the head is not strong enough to keep the air/petrol emulsion velocity high enough thru the large venturis and is allowing fuel to drop out of suspension.

[Anonymous]

erm mate
they were fine on my mates astra
so how can they be the wrong carbs?
they came off his car mint

he forgot to tell me about o ring things

i used sum instant gasket (i didnt know anybetter and bloke in shop told me it would be ok although it doesnt set rock hard or anything and is still sqidgy even now (whats left ov it!) lol ;))

i fitted the carbs to mine and they were shit

astra and novas share the same 1.4 engine

its sucking in air from between the carbs and manifold

the popping is coz the mixture is to weak (because ov excess air being drawn in)

anyways if they isnt fixed when the plate things come then i will ask mc coz he seams to know his 40`s

Micky@novaload.net :)

[Anonymous]

I got a 1.6 on twin 40's producing 150bhp and it has 30mm venturis. I had assumed that you had sealed the inlet tracts OK.

[Anonymous]

lol, Micky, CP is my mentor. He is eqaully knowledgable in the world of 40`s. Its difficult gettin all of the info accross electronically so confusion arrises.

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Whoopass! :D

[Anonymous]

no probs then cheers

apoligies allround

anyways there runnig smoothly now but i dont think there that much faster than standerd at moment.
they will do till roling man gets em
cheers for the help chaps

at least i can drive it now although sumtimes the revs still take a while to drop and the idle speed fluctuates between 1100 and 950.

anyways cheers once again



Micky@novaload.net :)

[Anonymous]

A mate of mine fitted 45 without the O rings and had problems due to the vibrations, fitting the O rings solved his problems, it was due to the vibration transmitted to the carb.

"Theres something missing, I'm not all there, Theres something missing".

[Anonymous]

Get large inlet valves in and start kicking ass M8!!! Bit disappointing without and thirsty- I put twin 40's on me 1.6er without enlarging the valves and only got 116hp on a (notoriously low reading)rolling road. Getting the head done (ins & outs) added over 30hp.:D

[Anonymous]

i havent even noticed any major increase in petrol consumption yet
so maybe my rejetted 2E peirburg was chucking far to much in

Micky@novaload.net :)