what te diffקrence between weber 36 and 40?

[Sprint_1.7]

my question is what the real difference between the 1.7 8v twin weber 40 engine, to twin weber 36 engine? any hp difference?

amit.

[psycho]

Im sure the choke sizes are different, i think the 36's have a 32mm choke and the 40's have a 36mm choke,sometimes not always, power can be found by swapping them,the bigger the choke the slower the airspeed.

[Greek]

36 were for 1500cc and 40 for 1700cc. Most common boost for the 1.5 was to replace th 36idf and put the 40 from the 1.7 with some exchaust tuning and new needles.
Some owners of the 1,7 were replacing the 40 IDf with other form VW beetle or porche to gain some hp but accordingly there was an increase in fuel consumption.

[Sprint_1.7]

o.k, tank's.

so what the ultimate set-up?

now the car with original delorto 36 mm and i want to replace them by weber 40 mm from alfa 33.

what this change really can give me? and what things, upgrades i need for this replacement to take some effect on the power of the car.

the car is Sprint QV 1.5 with 1.7 8v engine.

Amit.

[greku]

my 33 has a 1.3 engine and it is with weber 40's. is it normal?

[AllthingsZagato]

No, especially if;
1. You have 2 of them
OR
2. You have a single DCOE carburettor

[greku]

it's a twin carb 2 downdraft, previous owner said they are from factory. could it be???

[Greek]

@Greku : 1.3 with 40idf is not a standart most propably it should have 36 . Maybe your fuel consumption is way high , just check with someone else that has a 1.3 33 to compare...

@Sprint 1.7: I guess that you changed the engine but not the carbs. As i told you before the 40 idf are standards for 1700cc so using 36 you might have less HP that 118 . if you want something more try to gind idf 44 from a 2000cc beetle or an old porche (thos 2 models have idf carbs) to gibe a good boost. keep in mind that in order to have a good increase in perfomance you should change few other things lie the excaust (pore free or an ANSA type) or just stick to 40idf witch requires no mods on the engine.

[Sprint_1.7]

The problem is that's in Israel we don't have any old beetle with 2.0 engine and the Porsche, the old is very difficult to find and the part will be very expensive.

the reason that you sad about 36delorto on my 1.7 engine sounds logical to me.

Amit.

[alfavirusnz]

Amit,don`t worry whether you have 36mmor 40mm IDF`s-the only difference is the internal diameter of the carburettor barrels and the chokes and jets can be altered to suit engine sizes from 1-2litres. the 36 IDF Webers were an unusual carburettor, made I understand ,specifically for Alfa and when the Boxer was coming to the end of its life (in carbed form) they converted over to the far more common 40mm size not because 40 IDF`s produce more power, as the 36`s could have been kitted with identical venturis and jet sizes for the 1.7 engine. I have fitted 36 IDF`s onto our 33 1.7 from my 1.5 Alfasud Ti (produces far more power and torque than the 1.7 33 with what I have done to it) and the 33 ran fine with more bottom end power but too rich at top end (all with the 30mm choke-the 40`s on the 1.7 33 run 32mm chokes). Check the jetting on your 36`s and surprisingly the carbs may give you a flatter power curve than the std 40`s 1.7`s come with.

Richard J

[Spooty22]

If you can find a late 70's Aston Martin V8 Vantage, you can use the 48IDFs.



But that would be a bit silly, really.

[oz3litre]

Quote:

Originally Posted by Sprint_1.7 The problem is that's in Israel we don't have any old beetle with 2.0 engine and the Porsche, the old is very difficult to find and the part will be very expensive. the reason that you sad about 36delorto on my 1.7 engine sounds logical to me. Amit.

[greku]

Quote:

Originally Posted by Greek @Greku : 1.3 with 40idf is not a standart most propably it should have 36 . Maybe your fuel consumption is way high , just check with someone else that has a 1.3 33 to compare...

[alfavirusnz]

Greku, it may have been that the later 1.3 litre cars were fitted with 40IDF`s appropriately jetted and with appropriate sized chokes-if this was the case it doesn`t matter whether the car has 36`s or 40`s power and fuel consumption the same.
Regarding the series 3 version 33 in some markets they may well have still had some carburettored models-I suspect the cheaper, smaller capacity versions that you would have only seen in their own domestic and perhaps selected European markets.

[Sprint_1.7]

Thanks you all.

i found an weber 40 mm from alfa 33 1.7

for now it's will be the set up.

great forum you have here!

Amit