forget cams and 45s
the simple way to get a faster alfa is the carbs jetting
up choke to33mm idles up and mains up and there you have it
12 hp overnight cost $150
Is this for a 2 litre?
If it is, they really should of had 33mm or even 34mm chokes straight off the bat.
From both a Haynes workshop manual for the Alfetta's, my Hawnes WS manual for Weber carbies and I also reckon an American book I have on Webers, all said that with only 1 tiny difference, the carby specs of the 1.8 and 2 litre carbies were exactly the same.
What is also the same is their quoted power; 120HP.
A 12hp increase is a nice little bonus for you.
yes it is for a 2 litre as they use the 32mm chokes from 1.6 ,1.8 and 2 litres
I think part of the problem why it wasnt offered was in the 70s no cnc machines and 33 mm chokes just werent made they made 34 s but for a standard application its alittle large and you loses its flexibilty and really larger cams should be utilized,
This is on dellortos not sure about webers
trumpets will need slighlty larger jets again
The 2 carbs are so similar in their operation, that I'd guess they were the same specs for Dellorto's, too.
Something to keep in mind about car manufactures, is that they really are just running a business. So buying HEAPS of 1 type of component and using it over multiple different ranges, makes plenty of (financial) sense.
After all, it's not like they didn't know how to have fun, it's just that the accountants were a bunch of kill joy muppets....................... :P :P :P
yes and their main market was italy and they sold lots of 1.6 in fact 4 times more than 2,0 ltrs
so they didnt have alot of interest in the bigger cars which were mainly export and in america with californian pollution laws they made 1 model pretty much for all export models with minor differences
Hi there sounds interesting here are the original specs of the dellorto 40mm fitted to 2 liter alfetta which components below do you recommend changing?
Venturi: 32mm
Main jet: 1.45
Main emulsion tube: 7772-08-28
Main air metering jet: 2.10
Idle jet: 0.52 to 0.55 according to date of production
Idle air metering jet: 2.20
Progression holes: 1.2-1.6-1.6-1.5-1.5
Choke jet: 0.70 to 0.80 according to date of production
Choke air metering jet: 1.50 to 3.00 according to date of production
Choke emulsion tube: 7482.3
Acceleration pump jet: 0.33
Accelerator pump delivery volume (20 strokes each barrel): 5.0 to 6.0cc or 7.5 to 9.5cc according to date of production
Fuel inlet needle valve: 1.50
2 ways to go if you keep that emulsion tube
33 choke
148 -150 main
59-60 idle jet
or if you have the 11 tube not the 8
then you change main to 152-155
and the idle mixture at 3 turns out
probably should elaborate
with the emulsion 11 tube you change the idle to 60
and main depending on the characteristic you prefer 152 or 155
I am also working on a 59 idle 150 main with a 10 emulsion tube setup
waiting on tubes
these setups are for what is probably referred too as a stage 1 development
lots of fun thou takes it from doughy to grunty
not that doughy is bad ,its just a tad boring
Carlo, I have emulsion tube .7 (its what came with car - from what I've found one of the richer ones) Any ideas what other jet sizes I should go? I like grunty :)
what is the the carby model and year of car
sounds like an early e series dellorto
Dellorto dhla 40 - not sure of specifics tho. 84 gtv
It did come with early style steel cylinder air filter - maybe it's has a swap job done on carbs too.
on 1 side of the carby will be the word dellorto on the other sude will be dhla ????
can you tell mnje the ,main njet you have anf the air corrector on top of the stack and the idle that you run
all easily found under the rectangle cover held down by 2 screws and then pull the jet holders out
most australian alfas have dhla f or g and 84 alfas should be L series so you should see 40dhla L
on top of the second throat
Yep they are dhla40 L as you suggest.
I think idle/ choke is 55, main is 145, corrector is 200
Do they sound right?
strange numbers ?
should be 240 or 210 for the air
145 or 148 for the main jets
and the idle should be 55 or 57 its not the choke the choke is the main venturi
can you check these numbers precisley and the emulsion tube number exactly
given that you need to purchase 33 mm venturi or as the english call chokes
you need a 148 main(you may have it already)((should))(((this depends on the emulsion numbers)))
you will need 59 idles
Ok, sorry for confusion - I'm new to this:
Both emulsion tubes 7772.7 and mains 145 and corrector (on top of emulsion? ) 200
Th other 2 smaller tubes both have a 55 jet on the btm - this is idle?
Venturi - based on my manual drawing, this is horizontal (not vertical like the others?) And is on the part that sticks up out the top of the carb between the 2 throats? This should be 33?
And 240 or 210 air, which will be better?
Will your numbers work with these emulsion tubes? I haven't read about these .7's anywhere else.
Car is registered but primarily used for track sprints and spirited highway driving.
the emulsion tube is fine
the air corrector is fine
you need to buy 33 mm chokes they are literally 3.3cm in diameter internal they are located in the throat itself you remove the small venturi and it is located behind this just before the butterfly
there is a retaining nut on the outside of the small venturi which will release both just reach in with your fingers and pull out!
the 33 you are referring too is the accelerator pump jets be carfeful when you put them back in look at it carefully on the side of the larger bit it is flat if you do dont match it wont seat and almost impossible to put it back in the flat section faces outward ( not toward the engine)
where you found the 55s they are the idles they need to go to 59 if you use the larger chokes
http://www.aircoolednut.com/erkson/ttt/engine/carbs/Image17.gif
http://zsiguli.hu/images/cikk248_dhla_kicsi.jpg
the choke is number1 and 2
these diagrams should help
im interested to see what are you running in chokes the jettings are very good
it should be 32mm
forgot to mention the 148 main jets you will also need '
So it 33mm chokes 59 idles,and
4 of each around $150 from dellorto uk
Hey thanks a bunch Carlo, that helps a lot.
I assume I have to pull the carbs off to get to the venturis/chokes as they're in the barrel? Being primarily track orientated would 34mm be worth it or too much? I have the 10548 cams.
I haven't pulled the accelerator pumps out, so I might just leave them be.
How do I get the main jets off the btm of the emulsion? Are they threaded/pressed can't really see?
then I just combine what you said earlier:
'forgot to mention the 148 main jets you will also need'
So it 33mm chokes 59 idles,and
4 of each around $150 from dellorto uk
ok the jet just pulls off the end ,might need pliers ( gentle)
No you dont need to remove the carbs you will see on the side the retaining nut for the secondary venturi marked 91 and 65 at the M diagram remove this and put 2 fingers in and pull
im little worried about how you new the accelerator jets without removing them?
if you pulled one out make sure it is seated right marked as 7
yes thats it really, it is that easy once you have the parts
the specs for the 34mm chokes are but I think you will be happy with the 33mm
34s will require 60 idles and 152 mains
try both the 34 is for constant high speed
33 is for all round or tracks with tight bends
Ok, great that helps. Think I'll start with the 33's.
Didn't touch the accel pumps - hence so many questions (first). My Autobooks Alfetta manual explains items 34 - 25 as 'choke unit' which I haven't touched yet (but your diagram 'M' clears this up). I guess it means 'actual choke with cable' which I don't use.
I owe you a beer for all these questions - thanks again!
Damo,
I have the Speed Pro Series book "How To Build and Power tune Weber & Dellorto Carburettors" if you'd like to borrow it.
Cheers,
Brent
Sweet Brent, wouldn't mind a read.
Is it a Jim K book?
I have the how to power tune alfas one but it's a bit too 'extreme' for my needs at the mo.
Might head up the hill in the new year if ya free.
DB
Damo,
Same series of books as Jim K but not one of his.
Give me a buzz on 0418 215 259 when you want to come up here for a spin. I'm kicking back into campaign mode on Jan 5.
Cheers,
Brent
it would be interesting to see what the book recommends
can you post the specs it recommends?
cheers
Yep, will do.
Choke is 32 currently as stock.
yeh the 32mm choke is too small considering it was used from 1.6 up to 2.0
I think you will like the 33 nice not too much the GT approach .the problem I find with tuning books is they are either english based hence pushrod or sohc and then over the top to get the power out ( to sell books)
or if they are american which really is only for large v8s again asthmatic beasts that tear the tyres off but produce mediocre top end ( generalisation obviously . no bias at all) then you have european
which like english 4 cylinder based but designed to sit at 200kmh plus all day
we have one huge issue we are halfway between english and euro and with that in mind the books can be more useful.
I like to think we have found the jettings that if all things were equal and they didn't have to conform to 'strict pollution laws or pander to 80 year old ( sporting none the less descerning ) ladies going shopping this should have been the setup .
Yep I like the sound of that approach.
Gonna give it a try.
ok the best all round setup with the 33mm chokes is the 148 main jet ( standard on some australian alfas )
8 series emulsion tubes 210 air correctors, 59 idles and 2.5- 2.75 turns out on the idle mix screws ( IF IT POPS alot on deceleration screw out another 1/4 turn)
and all can be done insitu
no need for dynos or tunes as long as they are balanced
ps some of the old manuals from the 60s and 70s show you how to balance its not that hard
Just waiting on bits - chokes, mains and idles from dellorto UK. They only went back to work on Monday so next week I'm hoping. Your theory makes sense so keen to see it applied.
have the bits arrived yet
Yep have put them in and testing at lakeside on Sun. Initial trials on the street seem good - seems a little more punchy, difficult to test properly tho - lots of flashing lights around over summer period. It's quite fuely smelling at idle tho - is this normal?
If the idle screws are too rich it'll smell really fuely at idle - even set right they smell a little fuely at idle.
Quote from: LaStregaNera on January 30, 2015, 08:50:22 AM
If the idle screws are too rich it'll smell really fuely at idle - even set right they smell a little fuely at idle.
Yeah, maybe it's just me looking/smelling too hard. Screw out is richer and in is leaner right?
Correct! I do 4 full turns as per factory spec in the hayne manual
well you are running richer emulsions but check the idle mix screws around 2.5 to 2.75 out from all the way in
the further out the richer which if yoiu have basic australian carb with 11 emulsions you have too use for idle mix
so 4 turns out is for stock 2.5/2.75 for modified
2.5 turns has worked a treat. Did a pb at the track today so that's a plus. Got a shredded cv boot now, back Into the garage I go. Cheers again for the tips.
well done! hope to hear more sorry i didn't get back to you earlier i was away
cheers
Damo have you had it out again?
Yes mate, took around 1/2 a sec off my lakeside time but only did 3 of 5 avaialble runs as I had a split cv boot spraying grease on my rear brakes. Went faster each run so possibly could have gone quicker too. A worthwhile upgrade, cheers for all your advice.
what sort of aircleaner are you using
can you post photo of engine bay
cheers
hope you are powering on
Have the old style 105 cylindrical steel one.
see if you can get hold of the 83 to 87 alloy base one it has runners like half ramtubes
then you radius curve the upper edges and the filter don't worry about the square plastic top just cable tie it in the middle
you'll love it . there is one on ebay
get 5 hp boost
Can you take a photo as an example? Do you mean not to use the black plastic cover?
Mr Rossi means just cable tie the (flat) filter onto the top of the alloy lower half, no top cover (so no restriction in inlet). Or at least that's what I think he means... Or you could fabricate a more free flowing cold air intake by hacking up that cover + some large diameter hose (untested, but I did check flow on something similar that I really need to get my act together on and test in practice).
yes ill send a photo its great for low end speed but the top cover makes a big diff at speed ie over 100 kph
but these covers are hard to by, because they are plastic they didnt last well
so for damo racing maybe just a cable tie could do be better outcome , but if you have the cover use it and you can get a second air ram of the hot air inlet
ps the canberra show was great ,racing ferrari's down the highway ( I was not racing ) they were racing each other
sits very happy at speed wont post the actual speed
I have the plastic bit original wondering if I should remove it or keep stock I blocked the second air pipe that goes to the exhaust side as its hot air on that side thought would be best to keep only cool air coming in
yes thats the one and it works better with the lid on over 80 kmph doesnt sound as good thou
what jets are you running? if you have stock cams using 145 main with /8 emulsion and 57 idles works best in essence almost euro spec , 33 mm chokes and stock cams 145/148 main /8 emulsion 59/60 idles (2.5 turns out)
I will get some dyno figures on wednesday.to qualify it
Damo next time you track the car try the 145 main i think its a little sharper than 148 considering also that you have the race 7 emulsion tube
love to see outcome, good luck
Yeah, you think it'll be an improvement? It's easy to change so I might have a play.
Given the success of such small changes, it would be interesting to see the results of having some nice and accurate 3D ignition timing control.
When I had my Giulietta, I noticed how much nicer it's idle characteristics were when I advanced the ignition timing. Now I was smart enough to know that simply winding 10+ degrees of additional advance into the engine running from a mechanical advance distributor wouldn't work. But when you see any programmable computer or factory computer's ignition map, you realise just how much low load ignition advance an engine can accept.
Being able to accurately give the engine the ignition advance it wants at any given rev and load point is a huge plus.
ok on the dyno lost 7hp with the 145 main
go back to 148 and the 60 idles feel better and im trialing 42 accelerator pumps
ill have dyno results on thursday
I have booked a weekly session til its right
cheers ps dont forget to lub the weights in the dissi wd 40 lightly there is a window on the side
In mine I think the 145 is a bit more responsive (on the road). Gonna take both to the track next and swap after a few sessions - will see what happens to lap times when it's under the pump. I guess mine could be different with different emulsion tubes and corrector s etc. Keep us updated on the dyno results.
on dyno lost a little but it was sharper try 60 idles with 145 main
ok this is the best outcome on mine
60 idles 150 mains series 8 emulsion tubes 210 air correction
the difference in mine between 145 mains and 150 is around over 9 hp
and of course 33mm chokes
Wow, that's a big difference. I've got some leaky gaskets to fix and will put these extensions between mount and carb and see how that goes with the 150 mains.
yeh its like a small power band after 1/3 pedal you can really feel it
interesting thou without the airfilter lid on the `150 main felt a little too fat
so by putting the lid on generally with the supposed restriction in air flow you lean up a bit because the full filter
makes it richer ( in Normal cars) not so with the alfa
they must have really done there homework on flow because it does go better with the full filter on
bearing in mind thats the late model airbox not the older cylinder style
that new box is quite a clever in its airflow dynamics
ps I slighlty modified it
I have spare if you want, only the base thou , not the plastic top