First drive running rough, 2.0 weber 40's Options

[skota23]

Hi Folks,

I was able to take my new to me 914 for a short drive yesterday. The car is a 74 with what I think is the original 2.0. It has Dual weber 40's and what I think is the stock distributor. The cap and rotor look practically new and the plug wire in good condition. It wouldn't start a few weeks ago and I pulled the plugs (NGK 7) and cleaned them, fired right up after that (Never had webers before and I think I flooded the cycling a little pumping the gas pedal thinking it would help start.

Other observations.
The few times I have started it (usually after sitting over a week) I crank the engine, and give a dab of the gas pedal to get it to fire, usually takes several tries to get. running. After warming up a bit engine goes through revs well.

On the drive the engine runs very rough usually between 2-3k its barely pulling. Lots of hesitation and at odd times it pops to live a pulls great.

My first thought is to pull the carbs, do a thorough cleaning and check to see what jets are fitted and the condition of the floats.

Also planned are a timing check, valve adjust, oil and filter, fuel filter.

Is there any other details I can provide for suggestions on how to get things running well? (IMG:style_emoticons/default/poke.gif)

Thank you!
Steve

[rhodyguy]

As produced 40s work pretty good on a 1971. It’s the 44s with the big Venturi that are dogs on smaller displacements. Back snapping and popping. Terrible transition. No telling what sort of cam is in the poster’s engine. A lot of unknowns. Starting with the fuel pump.

[CCE]

As produced 40s work pretty good on a 1971. It’s the 44s with the big Venturi that are dogs on smaller displacements. Back snapping and popping. Terrible transition. No telling what sort of cam is in the poster’s engine. A lot of unknowns. Starting with the fuel pump.

I have the 44s and yes on the back snapping, yes on the popping, but transition? Sorry can’t understand, (second lenguage issue here). My motor is 1974, 2.2L with ported and polished heads and manifolds. I use the car in high altitude Mexico City.
https://youtu.be/LIo7AnmsMPo

[Superhawk996]

I have the 44s

Basically 44s are too big. Especially so at high altitude where air has less density and requires less fuel.

You need to find Venturi’s that are about 28mm diameter to get a good vacuum signal. Rejet after you replace those. You’ll still have issues with off idle performance due to the larger 44mm throttle butterfly but it will drive better.

Ideally you should sell the 44s and use a set of 40s. In my experience running 40s on a 1911 cc engine with a performance cam, it needed smaller venturis 28s for good driveability. 30 mm Venturi’s were better on the top end at high RPM but that is not how a car gets driven in normal traffic.

@bbrock is at similar altitude - he posted his carb and jetting setup (for 40s) a while back.

[GregAmy]

Basically 44s are too big.

(IMG:style_emoticons/default/agree.gif)

Somewhere in this forum there's a chart from, I think, the Dellorto bible, but I can't find it now. Attached is bascially the same thing.

CB has 44 IDF venturis available down to 32mm:

https://www.cbperformance.com/product-p/6356.htm