1600HF Rubber gasket carburettor

[ekranoplan]

I have originla Solex 42 mount and my car has 1600 inlet manifold - both the rubber and ally manifold are slightly different to 1300. I use Weber 45 plus adaptor onto original manifold so inlet tract is quite long.

best

[Ed Levin]

lancialulu Wrote:
-------------------------------------------------------
> Hi Ed
>
> My 1600 sport has 35 Dellortos in place of 42
> solexs on std manifolds.
>
> I have 45 Dellortos on an adaptor which I have yet
> to try which I agree are different barrel spacing
> from 35's.
>
> I did wonder if 40's would be a direct replacement
> for the 35's as the 35's which are fantastic for
> low down torque run out of puff a 5000 rpm in 5th
> (c100mph in the sport).
>
> Tim

Tim,

If they fit directly on the stock manifold, your 35 Dell’ortos are DHLBs – made with the same barrel spacing as the Solex specifically as an aftermarket swap for the Solex 35 PHH used on the 1300 Fulvias. Dell’orto 40s and 45s. are DHLAs, and these have the same wider barrel spacing as Weber DCOEs, as I mentioned before.

Although I don’t have any personal experience with them, Dell’ortos 35 DHLB are the same as DHLAs except for the barrel spacing), so I wouldn’t necessarily be in a rush to change them. The question is what size chokes you want to run. As I understand it, 35 DHLBs will take a maximum of 30mm chokes. Based on your description of good low-end torque, I'd guess you're running 28mm or 30mm chokes. If you're not already running 30mm, I'd suggest you try changing to those, and seeing if that works for you--if it does, I’d stick with the DHLBs. If you're already running 30mm chokes, and you want more top-end power, you'll need larger chokes, and this means you'll need to use your 45 DHLAs and your adapter. But 40s won't help you at all; they're DHLAs just like the 45s you already have.

[lancialulu]

Phil

Dont forget to check if the carb support bracket is missing - fixed between aircleaner housing and oil filter housing - often missing and therefore puts too much strain on the rbber mount.

Tim

[lancialulu]

Ed

good advice on the 40's thank you!

Dont get me wrong I like the 35's and on a rolling road with balanced and ported head with some var1016 near copy cams by Holbay it has put out 135bhp at 5000 rpm! I should say the exhaust was also specifically tuned for a low down torque performance to enhance the car's GT capabilities. Its just so annoying that you know the car has so much more in it and the carbs are the limiting factor at the top end. I will check the chokes but suspect they are 30's (or even 31's as offered by my Dellorto book?) as they were set up by a dellorto specialist at installation.

On the 45's do you have a jetting/choke guide for your 1600?

I guess the manifold adaptor as in the other post will through the longer inlet tracts be biased to lower end torque and still strngled at the top end. What I should do is look for a pukka gp4 manifold like you have.

Tim

[ekranoplan]

Coming soon a better than so called gp 4 manifold in best quality stainless - not cheap but suitable for all fulvias.

[lanciagarage]

Well today saw the modified Gasket being fitted, and after a little adjustment and resetting of the ignition timing, she is running very smoothly and pulling strongly from low revs in every gear. Top revs seem to be a little low as she seems to be strangled at about 5500 rpm.

Any suggestions regarding this?

[Ed Levin]

Tim,

If you're getting 135bhp at the wheels, with plenty of low-end torque, I'm not at all sure I understand what your problem is--even if the power is dropping off at 5000rpm. Personally, that's a problem I could live with...

Whatever the problem is, I'm not convinced it'll be solved by running 45 DHLAs on a cobbled together manifold and adapter; I strongly suspect that the adapter will take away as much as the additional choke size might give. But if you do source a good DHLA manifold, I'm sure there are a number of good Dell'orto tuning guides--not something I can help with, though, as I'm running Webers.

[Ed Levin]

Phil,

It's really impossible to diagnose these things without knowing any of the details of your engine and carbs. But if it's pulling strongly from low revs in every gear but running out of revs at 5500, there are a couple of obvious possibilities. You may be running small venturis (chokes), which give good low-end torque but not enough high-end power.

Or it may simply be that your jetting is way off--your previous jetting may have been compensating for the fact that the cracked carb rubbers were letting in additional air downstream of the carbs. But I'd say this is less likely, given that it's running smoothly and pulling well from low revs.

[lancialulu]

Phil

did you say you were running 42's on a standard 1600? If so it is unlikely that these carbs can be anything but standard. As posted earlier my 1600 is strangled (noticed on the road in 5th as a start of hesitancy as approaching 5.500) is due to the smaller carbs. My 1600HF with 42's is not strangled (but it is when I put the 35's one for an experiement - drove to Turin for centenary and had to limit run on motoways to 5000rpm). I assume you checked for alignment and no stepping between the carbs and manifold?

You may check ingnition timing - could be retarded.

Tim

[Ralph deMasi]

If you can take the engine, in all the other gears, to beyond the 5000 rev "wall" then the "running out of puff" in top gear may be due to something else...gear ratios?