I actually thought the standard carbs were 36 mm Before bigger carbs will be of any use to you, you need to have the cylinderheads ported and some uprated camshafts.

Actually, I would go for the cams first, then get the heads ported. 40 mm carbs can easily feed a 150 Bhp 2.0 engine, they just need some recalibration.

 

I think the gearboxes on 1.7 33s (and presumably 1.7 Sprints) had the tallest gearing. Guys in my local Alfa owners club who race boxer Alfas fit gearboxes from the early 1.2 Sud (?) because that had the shortest gearing, best for acceleration and track work.
Bad for fuel economy and long-distance motorway driving!

 

Thanks for the advice! Actually my sprint had a 1.5 engine so the gearbox i have is that of a 1.5 engine. I only changed the engine, not the gearbox. So i will tell my mechanic to find me some cams (i will go for the semi race not fullrace i think...) will it be difficult to find them ? I think i will find used ones no ? Once i was browsing through piper cams web site - but those were quite expensive to get as new!

Thanks!

 

You should also try to find an ANSA crossover exhaust manifold, or replicate it if you can find an old one in any shape. It has done wonders for my Sud's 1.7 8V with no other changes so far, especially at the 3000 to 5000rpm range.

 

i guess its very difficult to find one though ? especially in Malta...!

 

i guess its very difficult to find one though ? especially in Malta...!

I believe CSC make a similar crossover manifold which was still listed on their website recently. That might be easier to get hold of. I don't know what sort of roads you have there, but the crossover manifolds are lower than standard and can be prone to knocks - something worth considering.

As Hoygaard said, many 1.7s came with 36s so if you already have 40s then you should be fine with just jetting them to suit the state of tune of your head/cam. You would need to do some pretty wild head work to need anything bigger.

Buck

 

The Dellorto DRLA carb uses the same body for the 36 and 40mm carb, there is no difference, the 45mm is bigger and the 48mm even more. If you want to put a set of 45mm Dellorto's or 44mm Webers on then you will need to open up the inlet manifold where they bolt on or you will get no gain at all and i dont know how much material you can safely remove.
On my 1.7 8v Sprint i changed my standard 32mm venturies in my DRLA 40's for 34mm ones and removed the airbox and added velocity stacks, this alone made a noticeable difference, the only downside being that i lost some low down torque and driveabilty-the major power now comes in at 4000rpm-if you try to use full throttle at say 3000 rpm there is not a lot of 'pull' (torque). I also added a complete OMP group N exhaust system which is still available from Demon Tweeks.
Regarding the standard gearbox my 1.7 Sprint has, the ratio gives 20.7mph in top(5th)which is quite low in my opinion anyway, the 1.5 box giving an even slightly lower ratio, so your acceleration should be very good anyway.

 

The Dellorto DRLA carb uses the same body for the 36 and 40mm carb, there is no difference, the 45mm is bigger and the 48mm even more. If you want to put a set of 45mm Dellorto's or 44mm Webers on then you will need to open up the inlet manifold where they bolt on or you will get no gain at all and i dont know how much material you can safely remove.
On my 1.7 8v Sprint i changed my standard 32mm venturies in my DRLA 40's for 34mm ones and removed the airbox and added velocity stacks, this alone made a noticeable difference, the only downside being that i lost some low down torque and driveabilty-the major power now comes in at 4000rpm-if you try to use full throttle at say 3000 rpm there is not a lot of 'pull' (torque). I also added a complete OMP group N exhaust system which is still available from Demon Tweeks.
Regarding the standard gearbox my 1.7 Sprint has, the ratio gives 20.7mph in top(5th)which is quite low in my opinion anyway, the 1.5 box giving an even slightly lower ratio, so your acceleration should be very good anyway.

i would imagine you also lost allot of throttle response down low yeah? i would argue your mutch better of with good throttle response and torque across the rev range than loosing all that for 5 hp at 5000rpm...

 

The throttle response itself is still very good, and you can still accelerate quickly and even gently pull away from normal traffic behind you using small throttle openings and no more than 3000rpm, but its just that if you for example needed to overtake a couple of cars or an articulated lorry with not much of a straight and need to get past pretty quickly you have to have 3700-4000rpm showing to get the instant very quick acceleration. The engine note drastically changes at 4000rpm and you get a big power increase, which i have to agree is not always ideal for everyday driving, but i love it

 

The throttle response itself is still very good, and you can still accelerate quickly and even gently pull away from normal traffic behind you using small throttle openings and no more than 3000rpm, but its just that if you for example needed to overtake a couple of cars or an articulated lorry with not much of a straight and need to get past pretty quickly you have to have 3700-4000rpm showing to get the instant very quick acceleration. The engine note drastically changes at 4000rpm and you get a big power increase, which i have to agree is not always ideal for everyday driving, but i love it

sounds like a good compromise then...

 

are you sure 1.7s had 36 downdrafts i have had 5 1.7 boxers all 40s web and dell carbs

 

are you sure 1.7s had 36 downdrafts i have had 5 1.7 boxers all 40s web and dell carbs

Yeah it seems to be the case - alfa romeo arent to hung up about consistency

 

stick with the 40s .
if you are lucky enough to get past 180 bhp then you might need the 44s.
I had sud with twin 40s , 35mm chokes with 171 bhp
tried 45s gained nothing.

 

hi
a guy called edward has got a 33 series 2 and he has bored it out to an 1850 for a track car. i am thinking of doing the same for my 16 valve if i can get it done at a reasonable cost. there is an engine centre by me and they are really good so i might try them, they skimmed a head for me and only charged me £20
steve