Fitting Webers to my SC

[stuarts]

Gents,

As part of the major overhaul (and eventually the S/T backdate I'm planning), I'm looking to ditch the CIS on my SC and fit a set of Webers I've been offered.
Is there anything else needed on the fuelling side - change of fuel pump, pressure regulator, change of fuel filter etc?
Anything needed ignition wise?
I've already got fitted Turbo Thomas headers and a 2-in-2-out system.

Cheers!

[MikeB]

A non vac advance dizzy from a 78 car, is I believe the recommended ignition mod. I run with a Filter King to deal with the filter and pressure side of things. My system does not have a return line to the tank.

I suppose the alternative is the PMO regulator which still uses the return line.

[Jonny Hart]

You could do a lot worse than fit one of our CDI+ boxes. It will give you double the spark energy for starters, plus the ignition advance can be mapped if necessary.

We have a similar build being dynoed in a couple of weeks ( SC 3.0 plus PMOs ).

[23e Heure]

My 914 has a 3.0SC on Webers, and we'll be fitting one of Jonny's boxes when the car comes out of the paint shop next month...
Soon as I've tested it, I'll let you know how well that set up runs

[911hillclimber]

Watch out for the manifolds.
Ensure they cover any cut outs for injector etc.
I have full PMO carbs on my 3.2 and found gasket cover issues.
Insulation spacers are needed if you have missed them.

[fetuhoe]

Which inlet manifolds do you plan to use?

None of the standard intake manifolds used on early cars will be large enough to deal with the 39mm diameter inlet port of the Euro Spec SC engine.

The largest standard Weber manifold will be 36mm diameter at the outlet with 32mm being the most common.

If you don't match them to the port you will have a stumble and low revs.

You will need to fit at least 34 or preferably 36mm dia Venturis and depending on which Weber you have there could be some issues with progression and the accelerator pump cam.

A more mundane point concerns the throttle pedal. If you car has a late type plastic pedal then you will not obtain full throttle due to the position of the pedal stop.

The 'ratio' of the Weber Quadrant is different to the SC arrangement and the throttle on the CIS has less travel. You will need to cut around 10mm off the length of the stop that is built into the pedal.

The throttle rod that connects the manifold quadrant to the bell crank on the transmission also changes position and engine tinware will need a slight modification.

The fuel line diameter will also be unsuitable for connection to the Webers and you will need an adaptor.

I have some thermal insulators and gaskets that cover the injector port in stock.

[911hillclimber]

PMO do the right 'big-bore' manifolds etc for these big ported heads to save opening up some magnesium weber manifolds.
They also have sets of venturies sized to met specific engine capacities for a given size of carb which (I think) fit the webers.

PMO are very helpful people, esp if you can get to Richard Parr, the founder of PMO.
Well worth an email.

[fetuhoe]

40IDA3C venturis - various sizes

We also have the early IDA3C Accelerator Pump Cams which we have manufactured and case hardened as per the original parts and unlike some of the other aftermarket parts which as mild steel and will wear.



We also do a fairly subtle modification to the idle air corrector jet which allows it to be tuned. This mod allows the progression circuit to be modified which is not a standard feature of a 40IDA3C but is a feature of a PMO.

[911hillclimber]

Nice tweek Chris.
Having had my big PMO's for 6 years now they are really nice with several good mods over the webers.