105 Spider - rising revs

[Lotobear]

I know there are a few 105 owners on here. This query concerns a 1976 2.0 Spider Veloce.

I rebuilt the Dellorto carbs lasy year and have also fitted solid mounts and a new manifold gasket along with a 123 distributor. Car runs really well, strong, torquey and willing to rev.

The issue I have is pulling up to a junction on a steep hill (nose up) and idling. After a few seconds the revs rise on their own accord to 3.5k and increasing (quite alarming). Otherwise it's all good.

Any thoughts on what to look at? Suspicion is servos or vacuum takes off leak but the servos are recent (new) and the hoses look good. If it is a vacuum leak why would it only occur on a hill?

Cheers

[velocemitch]

Most of the distributors on the 105 are centrifugal, not vacuum, so I doubt its that.
I find mine tends to hang on to revs rather than them dropping to tick over, but not rising like that, seems odd.

[Lotobear]

...plus it has a 123 electronic dizzy.

I'm wondering about the floats and whether one is getting hung up or stuck down on the incline but am trying to figure how either would cause such an effect. It does tend to be confined to steep inclines

[craig_m67]

Fuel pressure regulator not working, to high a pressure overcoming the float ?

Or are the floats too high, incorrectly set?
(Last thing you touched and all)

In other news, I bought a 123 dizzy for my 1600GTJunior.. best investment I’ve made in over 30years driving Alfa’s!

[Lotobear]

Mechanical pump so pre set pressure

Float heights are as spec (plus car runs well in all other respects).

The old Marelli was worn out - bob weights flopped all over the place. The 123 has made all the difference, plus new solid carb mounts and a new inlet manifold gasket.

I'm impressed with the 2.0 Nord, it's a good strong engine with nice torque. I also have a Lotus Elan - the Lotus TC is a totally different animal and much more temperamental (though more character) but I like them both for different reasons.