Hello,
I have a Fulvia Coupe SII with a 1300cm 818302 (not 303) engine. The car is now beeing restaured and it will be ready in a few months (I hope). The engine has a pair of DHLB 32mm Dell'ortos. I wanted to ask, if my carbs are too small for the engine (since the originals were 35mm Solex) and if I should try to find bigger ones (dellorto 35mm or 40mm).
If I want to upgrade (should I ?), do I need to change the inlet manifold as well? What type of dellortos (DHLB or DHLA, 35mm or 40mm) would be appropriate or better? And does anybody know where I could find them?
Thanks a lot in advance,
Marios
Which carb for a 818302 ?
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Paul de Raymond Leclercq
Re: Which carb for a 818302 ?
As you say the correct carburettors for your engine would be 35mm Solexes (with 29mm chokes).
How is it that you have a SII coupe with a 302 engine? Has someone fitted a Fulvia Berline engine?
In your position - unless of course you prefer the 302 engine - I would be looking at least for a 303 head and camshafts, even if I left the pistons undisturbed.
If you can find them, then Dell'Orto DHLB 35s would be a good choice; I do not think that Dell'Orto made a 40mm DHLB (I wish that they had) - at least I have never seen or heard of them; they would be too big for your engine in any case.
To fit Dell'Orto 35mm DHLBs you would not need to change your inlet manifold - although you may have to change the mounting rubber(s).
Finally, port matching is usually atrocious on SII engines; take to opportunity to address this when you are making the changes and you will enjoy improved performance.
Paul
How is it that you have a SII coupe with a 302 engine? Has someone fitted a Fulvia Berline engine?
In your position - unless of course you prefer the 302 engine - I would be looking at least for a 303 head and camshafts, even if I left the pistons undisturbed.
If you can find them, then Dell'Orto DHLB 35s would be a good choice; I do not think that Dell'Orto made a 40mm DHLB (I wish that they had) - at least I have never seen or heard of them; they would be too big for your engine in any case.
To fit Dell'Orto 35mm DHLBs you would not need to change your inlet manifold - although you may have to change the mounting rubber(s).
Finally, port matching is usually atrocious on SII engines; take to opportunity to address this when you are making the changes and you will enjoy improved performance.
Paul
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Marios Nikolidakis
Re: Which carb for a 818302 ?
Hi Paul,
Thanks for your answer. When I bought the car, it had the 303 engine and the 302 was given to me by the seller as a replace engine, without knowing then that it was a 302. When my mechanicer took the 303 off in order to restore it, he found out that the head and the camshafts were not OK and he told me to bring to him the second engine, to try to make from the 2 engines one good. When he opened the 302 engine (still without knowing it was a 302 and not a 303) he told me it was in an almost perfect condition and that's why we decided to put the 302 engine on (I discovered it is a 302 a few days ago). The 32mm dellortos were in the 303 engine and I took them from it to the 302.
Do you think the 35mm dellortos will not be an improvement to my 302 engine instead of the 32mm ones?
If yes, do you have any idea, where I can find a pair of 35mm Dellortos DHLB?
Has the 303 engine a big (driving) diffenrence to the 302? I mean, 3 hp (90hp the 303 and 87hp the 302) is not such a big difference, is it?
Can you please explain to me what do you mean by "port matching is usually atrocious on SII engines; take to opportunity to address this when you are making the changes and you will enjoy improved performance"? (My english need help). What is "port matching"?
I asked you about the 40mm dellortos, because in the Omicron parts catalogue (page 12), they recommend 40mm dellortos for 1300 Fulvias.
Thanks for the help,
Marios
Thanks for your answer. When I bought the car, it had the 303 engine and the 302 was given to me by the seller as a replace engine, without knowing then that it was a 302. When my mechanicer took the 303 off in order to restore it, he found out that the head and the camshafts were not OK and he told me to bring to him the second engine, to try to make from the 2 engines one good. When he opened the 302 engine (still without knowing it was a 302 and not a 303) he told me it was in an almost perfect condition and that's why we decided to put the 302 engine on (I discovered it is a 302 a few days ago). The 32mm dellortos were in the 303 engine and I took them from it to the 302.
Do you think the 35mm dellortos will not be an improvement to my 302 engine instead of the 32mm ones?
If yes, do you have any idea, where I can find a pair of 35mm Dellortos DHLB?
Has the 303 engine a big (driving) diffenrence to the 302? I mean, 3 hp (90hp the 303 and 87hp the 302) is not such a big difference, is it?
Can you please explain to me what do you mean by "port matching is usually atrocious on SII engines; take to opportunity to address this when you are making the changes and you will enjoy improved performance"? (My english need help). What is "port matching"?
I asked you about the 40mm dellortos, because in the Omicron parts catalogue (page 12), they recommend 40mm dellortos for 1300 Fulvias.
Thanks for the help,
Marios
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Huib Geurink
Re: Which carb for a 818302 ?
Are you sure your engine is a 302 engine?
There may be 818.302 number on the cilinder block but that is the partnumber for the block. The block is the same for 302 and 303 engines and thus has the earlier 302 number. I expect the 1231 cc blocks to also have a 302 number. After the 302 engine was born, replacement 1216cc blocks were also 302 blocks but with a cilinder diameter of 76 cm instead of 77 mm as for the 1300 engines.
The correct engine number is on the flywheel housing were the starter motor sits.
You should have 35mm carbs for a relatively standard engine
The cubic capacity for 1 cilinder is 325 cc.
The max rpm is 6000.
The product of max rpm and cubic capacity of 1 cilinder is 1.950.000
The square root of this product is 1396.
Divide this by 40 and you get 34,9 which is the proper diameter for the carbs. Lancia did its homework well. Remember that engineers were the boss with Lancia at the time. Not the salesmen as with Alfa Romeo who put 40mm carbs on 1300 engines. In my opinion for commercial reasons.
If the engine is really a 302 engine you need 29mm venturi's and appropriate jetting. For the 303 engine you need 31mm venturi's.
There may be 818.302 number on the cilinder block but that is the partnumber for the block. The block is the same for 302 and 303 engines and thus has the earlier 302 number. I expect the 1231 cc blocks to also have a 302 number. After the 302 engine was born, replacement 1216cc blocks were also 302 blocks but with a cilinder diameter of 76 cm instead of 77 mm as for the 1300 engines.
The correct engine number is on the flywheel housing were the starter motor sits.
You should have 35mm carbs for a relatively standard engine
The cubic capacity for 1 cilinder is 325 cc.
The max rpm is 6000.
The product of max rpm and cubic capacity of 1 cilinder is 1.950.000
The square root of this product is 1396.
Divide this by 40 and you get 34,9 which is the proper diameter for the carbs. Lancia did its homework well. Remember that engineers were the boss with Lancia at the time. Not the salesmen as with Alfa Romeo who put 40mm carbs on 1300 engines. In my opinion for commercial reasons.
If the engine is really a 302 engine you need 29mm venturi's and appropriate jetting. For the 303 engine you need 31mm venturi's.
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Paul de Raymond Leclercq
Re: Which carb for a 818302 ?
35mm Carbs are correct as Huib rightly says. You can get good performance with 35s; as Omicron states however, a race or rally engine would probably benefit from 40s provided that the rest of the engine was developed to suit - especially in the exhaust department. However as I wrote before, with the 40s you need a special inlet manifold; these are available.
As for finding a set of 35DHLBs - keep looking and best of luck! Many people are searching for these excellent carburettors. You will have to pay probably the equivalent of 500 euros I would guess for a pair.
By port matching I mean that for example, the inlet manifolds never line up properly with the inlet ports in the head: there is a step. This should be removed. The same applies to the carburettor mounting rubbers. You can do this job with an abrasive flap wheel in a high-speed drill or better a die-grinder (20,000 rpm).
This is not so important on the exhaust side, as a step can actually improve spread of torque although for best power these too should be matched
Paul
As for finding a set of 35DHLBs - keep looking and best of luck! Many people are searching for these excellent carburettors. You will have to pay probably the equivalent of 500 euros I would guess for a pair.
By port matching I mean that for example, the inlet manifolds never line up properly with the inlet ports in the head: there is a step. This should be removed. The same applies to the carburettor mounting rubbers. You can do this job with an abrasive flap wheel in a high-speed drill or better a die-grinder (20,000 rpm).
This is not so important on the exhaust side, as a step can actually improve spread of torque although for best power these too should be matched
Paul
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Huib Geurink
Re: Which carb for a 818302 ?
If you go looking for Dellorto's make sure they have the correct jetting for your engine and that the Dellorto trumpets are included. The jetting is on www.viva-lancia.com/fulvia/qanda/carbs/dellorto.php.
The correct jetting for the Solexes is in the DT (Data Tecnici = Technical Data and Specification book). See www.viva-lancia.com/fulvia/qanda/docume ... via-cd.php
The correct jetting for the Solexes is in the DT (Data Tecnici = Technical Data and Specification book). See www.viva-lancia.com/fulvia/qanda/docume ... via-cd.php
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Geoffrey Goldberg
Re: Which carb for a 818302 ?
Huib -
Thanks so much for the formulas for determining venturi size. What assumptions are in this formula, if you please? Most interesting is the dividing by 40 part. Is there some assumption as to max air velocity through the carb, and is this any different for a side draft as well as a down draft carb?
Many thanks.
Geoff
Thanks so much for the formulas for determining venturi size. What assumptions are in this formula, if you please? Most interesting is the dividing by 40 part. Is there some assumption as to max air velocity through the carb, and is this any different for a side draft as well as a down draft carb?
Many thanks.
Geoff
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Huib Geurink
Re: Which carb for a 818302 ?
Geoff,
The division by 40 is for the barrel size. Division of the same term by 50 is for the venturi size. I got these formulae from a book some time ago. Friends call me Huib Alzheimer. Well, they would have been Fulvisti they would have noticed that my memory is not failing. Just selective. It only remembers important items, which are Fulvia related items. Anyway, they are valid for the side draft set up on Fulvia's with the double twin choke (or is it twin double choke?) carbs. I would guess they are also valid for downdraft carbs as long as there is one barrel per cilinder.
They are not the gospel but a rule of thumb to have intitial values when one starts to optimize an engine. If you check the various Fulvia's, the values are pretty exact. Important to notice is that barrel and venturi size are proportional to the square root of max rpm and / or cilinder size.
The division by 40 is for the barrel size. Division of the same term by 50 is for the venturi size. I got these formulae from a book some time ago. Friends call me Huib Alzheimer. Well, they would have been Fulvisti they would have noticed that my memory is not failing. Just selective. It only remembers important items, which are Fulvia related items. Anyway, they are valid for the side draft set up on Fulvia's with the double twin choke (or is it twin double choke?) carbs. I would guess they are also valid for downdraft carbs as long as there is one barrel per cilinder.
They are not the gospel but a rule of thumb to have intitial values when one starts to optimize an engine. If you check the various Fulvia's, the values are pretty exact. Important to notice is that barrel and venturi size are proportional to the square root of max rpm and / or cilinder size.