International Lancia Forums

I have just bought a 1972 1.6 HF and am preparing it for road rallying. Hence I would like the car still to be tractable at the bottom end of the rev range, say from 2000 rpm. I intend changing the exhaust and the inlet manifolds for "competition" ones, but I am in a intrigued by the carb choice that is recommended.
All my tuning books and carb setting programmes indicate that a 1600 engine producing peak power at 6200 rpm needs 40 carbs with a 32/33 choke size, yet Lancia folk seem to prefer 45mm cabs with 36 chokes, which would appear to be a "full race" set-up. Any thoughts?

What other mods, apart from porting the head and a set of cams, need to be done to the valve gear if you want to rev it to 7000?

Cheers

Michael

This is quite an old chestnut, and you may find the answers in previous posts.

A standard 1600 in good order should run to 7000, no problem.

As I have written before, Fulvias are very responsive to exhaust developments. The exhaust ports are very restrictive and in addition, the standard manifold is simply not up to the job. Unfortunately it is very difficult, indeed practically impossible, to find a good manifold for the Fulvia; best to find a GOOD firm and have them make one for you - very expensive because it is difficult.

When gas-flowing, do not forget the manifold, and port matching is usually terrible on S2 Fulvias this must be addressed.


The Fulvia is very different from other cars: hence the use of rather large carburettors. To give an example, a friend had a 1600 Beta that really went well and it used 40mm DCOEs with 32mm chokes. He was amazed when I told him that the 1600 has 42mm carbs with 36mm chokes as standard. The VAR 1016 "homologation special" version had 45mm Solexes with 38mm chokes for 132HP. And the final works rally cars used 48mm Webers or Dell'Ortos, but of course they had very low-ratio final drives.

The best solution for the inlet manifold is to find an adaptor manifold that bolts to the existing one; even the works used these. I think that they provide a better path for the mixture than the all-in-one manifolds made to suit 40s/45s/48s.

A word on torque. For rallying you would be best finding a sedan gearbox and building the final drive up with the 1600 gear set. The 4.1/1 sedan ratio would make the car more suitable for rallying although of course you may well be using lower-profile tyres which will improve acceleration.

And finally reflect on the weight. With a full cage etc., a S2 1600 will weigh very nearly a ton. It is worth reflecting that the works homolgated a rally Fulvia coupe in Gr IV at 780kg... You will need a full set of aluminium panels and fit a plastic rear window - this is legitimate since the 1300HF was sold as such. You might get away with plastic rear quarter lights too; glass is very heavy.

Paul

As always agree with what Paul states. I prefer 36 venturi's in 45's with all new valve gear to keep up with higher revs.

And yes, I also always hear that big venturi's on small engines is nonsense. But in our case it works!! I believe you combine it with long inlet tracts. Meaning long inside the head (for half of the cilinders...), long in the dhla/dcoe inlet manifold (all different as Paul states) and then long air horns (I use 150mm ones). Compare this with Alfa's where the all of the above are SHORT. No room under the bonnet to change that there. But I did find one tuner who used a similar LONG setup (more than 60cm in total) with HUGE carbs: Abarth. 48's on a 1300 engine.

OK, thought I'd give you some feedback on the results !!

I fitted Omicron's "competition" exhaust system and their "rally" spec cams as well as a set of Weber 45s on a Gp4 manifold. The ports of the inlet manifold were matched to the inlets, as predicted the S2 head was a bit out in this area. However, at this early stage of the tuning, there were no internal mods, so otherwise std ports and std compression. The engine had a Newtronics ignition system fitted ( i.e. a Piranaha system of old), so nothing too fancy.

It pulls cleanly from 2500 ( a bit of work on the idle jets should get it clean all the way) and produces a steady 105bhp at the wheels on what is considered honest rolling road at around 6200. It feels like it is still producing power at that point so higher revs might get a slightly higher reading, but we didn't take it much past that point, and certainly really comes alive from 4500 on.

I'm running 36 mm chokes, 145 mains, 200 air correctors & F16 emulsion tubes. Currently 50F9 idles and 45 pump jets, but these might change to get it clean at the bottom end. But it's pretty close at the minute just a slight hesitation at 2300 or so.


Cheers

Michael

105HP at the wheels is probably more than 135 at the flywheel, so if the rolling road was as accurate as you say, you have a good engine - remarkable in fact, without any flowing - at least of the exhaust ports.

Well done

Paul

Paul

It's a rolling road that I have used for many years and is certainly well respected here in Northern Ireland, so I feel its a pretty good measure

The engine was originally built in standard form by a local Stock Car specialist, so it looks like he got the bottom end just right.

It certainly makes the right sort of noises !!

Cheers

Michael

Hi Michael

I have been boring people stupid for years about doing some tuning work to my 1600HF, and your post has spurred me into action again! I'd like to know how you are getting on and whether it has made a significant difference to performance if you don't mind?

I had been thinking of a similar setup to yours, but was going to persuade an aerodynamics mate of mine to draw up an all-in-one intake manifold - I read from other posts that the adaptor is the way to go so that got put on hold. I was looking at Dellorto's, not Webber's - would still be interested to know what jet/choke etc combo you settled on.

Thanks

Pete