Porsche 914-dual weber 40 problems

[roywb46]

I have a 1974 Porsche 914 with a 2.0L engine. Engine has dual Weber 40 carbs (top ventura has #28 & jets say #120 on them). Unknown but doubtful if cam was switched over when someone installed carbs after removing FI system. My question is the motor runs good at idle and under acceleration up until about 4000 RPM then it starts falling on it face, like it is starving on gas. I have a fuel regulator set at 2.5 and unknown if fuel pump was changed or updated from the original FI system to a Carb system (20-30 psi --3-4psi). Still has stock points in distributor hasn't been updated to electronic ignition. Can't find any obvious vacuum leaks around bases on carbs etc.. Haven't pulled the plugs to see how they're burning yet. IS their a standard setting on the carbs I need to check..air etc..thanks for the help.

[Joe Ricard]

4000 RPM is where the Main jets are exclusively providing fuel for the engine.
So yes you need bigger main jets.
I have had good experience with 130 mains and 180 or 200 Air correction.

There some vendore that will swap jets while you are figuring out what size you need.

[roywb46]

Thanks for the advice, and your experience, Roy

[John Rogers]

Webers seem to like 3.5 PSI fuel pressure as a happy medium. You can check the pump to see what it looks like, if it is a barrel shaped pump and motor then it might be the FI pump and if it is a little square pump that buzzes and viberates it has been converted. One thing you can do as a test is to raise the fuel pressure to 4.5 to 5 PSI which is like raising the float level and do a test run at full throttle to see if it helps. The idle will be not too good, but ful;l throttle is better then the mains are probably too small as noted and can be replaced. Make sure to lower the pressure back to what it was before.

[Matt Monson]

What distributor is in there? It will run a whole lot better if you get a dizzy on there that's intended for carbs (unless that's already been done)...

[SGB]

If the fuel pump is a low pressure model like a Facet brand, you really don't need a pressure regulator. I had one with a low output pump and got similar starvation effects, so I took the regulator off. Of course, don't do that if you have the high pressure stock fuel pump.

[Racer Chris]

Don't raise the fuel pressure. 3psi is more than enough to keep weber carbs filled.
Get a set of 32mm primary venturis. That will allow the engine to breathe at higher rpms. After that you will need bigger main jets (up to 140), and maybe bigger idle jets. As Joe mentioned the air corr. jets should be 180-200, and idle jets should be 55 or 60.

[HarveyH]

If you're considering, or already have a "distributor for carbs", make sure it's not the 009 distributor. The 009 has an advance curve suitable for the Type 1 VW engine, not the Type 4. Any of the stock 914 distributors are superior to the 009. My car was carbed and cammed when I got it, and a 009 was installed. Eventually, I dug the old 914 distributor out of the spare parts stash, cleaned it up, and tried it, and got a noticeable improvement in every area of operation. The Mallory replacement distributor is also highly recommended by those who have used it, and I believe it comes with an assortment of advance springs for custom tuning.
Harvey

[last337]

I am having the opposite problem and am wondering which direction to go. I currently have dual 40s installed on a '73 2.0 the following:

52 idle jets
115 main jets
200 air jets
28mm venturi
F11 emulsion tubes

I am trying to dial these things in and after going with the lean settings (seated air bleed, 1 1/2 turns out mixture, 1 turn out speed screw) it runs fine but smokes and spits fuel as if it is way too rich. From what you guys are saying I am definitely in the ballpark as far as jet sizing and I would think I would just be seeing performance dropping off at points in the power curve but not this problem of running so rich and not being able to lean it up correctly. Any ideas? I think I have a stock cam

[hardflex]

Are you sure your floats are working properly? I'd Pull the spark plugs and see if they are rich on one side or one cyl only.