Porsche 914 2.0L (2056cc) Dropout Around 1200RPs to 3000RPMs, Dead Spots Between 1000 RPMs and 3000 RPMs during acceleration Options

[mturner7]

Hi Everyone,

I have a 1974 Porsche 914-4, 2.0L (2056cc) engine in it.
I have red-line Weber IDF 44's carbs installed.

ISSUEs

1) It starts up fine, A little rough until it's warmed up
2) Idles at 950 to 1000 RPMs
3) When I start off and transition just past idle, I get a few dead spots
- 1st gear, from 1000 rpms to 2500 - 3000 it lugs
- 2nd gear, from 2000 rpms to 3000 it also lugs
4) After getting into the 3000-rpm and beyond, the car runs great, good pull and excellent HP
5) I can cruse 70 - 90 mph all day long without any problems.
6) When I let off the gas at the lower speeds, say 30-50 mph I'm getting a popping sound kind of like a backfire. I'm sure the dead areas around 1000 rpms to 3000 rpms and the popping sounds are related.

Does Anyone have an approach to troubleshooting this?

What I've done so far is:

A) Pulled all the emulsion tubes cleaned them and cleaned all the p-jets and AC'c
- Main Jets = 1.60, idle jets = 55, ACs =200
B) Synchronized all 4 carbs.
C) Air flow set for all 4
D) Changed the spark plugs
E) Set the Idle Speed to 950 rpms
F) The fuel pressure is 3.4 psi
G) The car has Electronic Ignition (Flamethrower)
H) It has new spark plugs wires, rotor and CAP.

HELP!

[914Toy]

Sounds like the small diaphram pumps that squirt extra fuel down the carb throats every time you depress the accelerator, are not working well. Fixed by resurfacing these pump "covers" (held on with 4 screws) back to flat again (with fine sandpaper on a flat surface, like table top glass or granite), and repalcing the diaphrams. Sounds easy, but is very easy if your carbs are on your work bench!

[porschetub]

Hi Everyone,

I have a 1974 Porsche 914-4, 2.0L (2056cc) engine in it.
I have red-line Weber IDF 44's carbs installed.

ISSUEs

1) It starts up fine, A little rough until it's warmed up
2) Idles at 950 to 1000 RPMs
3) When I start off and transition just past idle, I get a few dead spots
- 1st gear, from 1000 rpms to 2500 - 3000 it lugs
- 2nd gear, from 2000 rpms to 3000 it also lugs
4) After getting into the 3000-rpm and beyond, the car runs great, good pull and excellent HP
5) I can cruse 70 - 90 mph all day long without any problems.
6) When I let off the gas at the lower speeds, say 30-50 mph I'm getting a popping sound kind of like a backfire. I'm sure the dead areas around 1000 rpms to 3000 rpms and the popping sounds are related.

Does Anyone have an approach to troubleshooting this?

What I've done so far is:

A) Pulled all the emulsion tubes cleaned them and cleaned all the p-jets and AC'c
- Main Jets = 1.60, idle jets = 55, ACs =200
B) Synchronized all 4 carbs.
C) Air flow set for all 4
D) Changed the spark plugs
E) Set the Idle Speed to 950 rpms
F) The fuel pressure is 3.4 psi
G) The car has Electronic Ignition (Flamethrower)
H) It has new spark plugs wires, rotor and CAP

HELP!

,
What size venturies did Redline supply with these ?,normally for 44's it would be 36mm if so you will most likely have to reduce to size to improve your vacuum signal with this size engine .
Spitback on throttle overun is caused by a rich condition,cheers

[yeahmag]

What advance settings are you using in the distributor?

[rfinegan]

3000 + your progression circuit is handing off to the mains. The mains are supplying the extra fuel and the circuit comes on with POWER.

Do you know what cam is in this 2056?

Tuning this transition can be difficult (I know) with the 36 vents in the 44IDF for 2056 t4
Smaller ventures will provide more signal/ vacuum and make tuning and transition easier and more drivable. 32mm vents was recommend to me by an EXPERT in the T4 world. I had 32 in my 40IDFS so I swapped out the 44s. New 32 vents can be had for 60-80 bucks.
IF you have place to test drive, pull your main stacks(4) and drive on the idle transition circuit. The mixture screws mostly work for idle and when the throttle is open the transition holes provide air fuel from there. The fuel will cut our about 3k as a very lean hole is there without the main jets to take over. Tune this with you idle jet size.
Once the idle is in range and driving well , you can tune when the Mains come on with the Air corrections and they the main jets and accelerator pumps

This may help:
https://www.aircooled.net/how-to-use-a-wide...-flat-4-engine/

Ill have more tips as I tune my jets this week end

[rfinegan]

What advance settings are you using in the distributor?

time suggestions from the experts gave me from my configuration :

base timing 10-12*
total timing all in at 30- 32*

so far mine like 10* and 29 total..but each jet or timing change has to work with each other

Do you have a CHT gauge and a Wide band O2 sensor for AFR?

I just got the Redline Jet-Pac for tuning me Webers Buy one Cry once.

rich or lean can carbs cook a set of head in no time as well as retarded or advance timing..so be carful and make small changes at a time

[emerygt350]

Just a thought... Are your weights in the dizzy gummed up?

[mturner7]

Sounds like the small diaphram pumps that squirt extra fuel down the carb throats every time you depress the accelerator, are not working well. Fixed by resurfacing these pump "covers" (held on with 4 screws) back to flat again (with fine sandpaper on a flat surface, like table top glass or granite), and repalcing the diaphrams. Sounds easy, but is very easy if your carbs are on your work bench!

Hey good guess!

My #3 & #4 carbs' accelerator pump is not working correctly. The #1 & #2 carb is squirting fine when I looked down the barrel. #3 & #4 carb's are dribbling fuel, NO Squirt. I took #3 & #4 carb apart again and cleaned the accelerator pump circuit and replaced the diaphragm. Still just dribbles fuel, so I purchased a new 6367 Weber Zero Bypass Valve to go into the bottom of the carb. Haven't got them yet. When I cleaned the old Weber Zero Bypass Valve, the ball-bearing was not moving around, it's stuck partially shut.

Thx -Monte

[technicalninja]

Pierce manifolds has a larger range of venturis for the 44s.

https://www.piercemanifolds.com/CHOKE_p/71507.htm

You've got "normal" jets in this with the exception of the mains which are way big IMO.

The carb came with 130 or 135 jets in it.

With the standard 36mm chokes it needs to be on a 2.4l engine.

With the normal smallest choke 32 it needs to be on a 2.2l engine or a WILD 2.0...

Pierce has 28s for the 44.

They would be better matched with a 40mm throttle but putting these in your 44s will solve 90% of the mismatch issue.

I'd order a set of 28 venturis, 130/135/140 mains, 180,190,210 airs

I'd use both a WB02 and a good CHT gauge.

Another upgrade for the accelerator pump is direct linkage. Most of the carbs came with a cam on the throttle shaft and a lever in the pump cover with a roller at the end of the lever. This lever is easy to get "off the side" of the cam. Worn out or bent levers are worse.
The later carbs come with a linkage that is directly connected between the pump cover and the operating cam (which now has a hole in it for this linkage).
I will be upgrading a set of 40s and a set of 44s to the newer accelerator pump design.

This is BIG change to the carburetor as you have to remove the throttle shaft and throttle shafts on Webers take some special tricks to replace...
Biggest tip: AlWAYS have new throttle shaft parts on hand before trying to do this and accept the original shaft/blades/bearings/seals/blade mounting screws are trash and are NOT to be re-used

[brant]

I'd guess venturi's also...
not enough air speed (velocity) for the small motor

[SirAndy]

I'd guess venturi's also...
not enough air speed (velocity) for the small motor

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@mturner7
44's are too big for a 2056. I had to choke mine down to 32mm venturis to get rid of the flat spot when coming off the idle jets. If you can get 28mm venturis, even better.
(IMG:style_emoticons/default/driving.gif)

[930cabman]

I'd guess venturi's also...
not enough air speed (velocity) for the small motor

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@mturner7
44's are too big for a 2056. I had to choke mine down to 32mm venturis to get rid of the flat spot when coming off the idle jets. If you can get 28mm venturis, even better.
(IMG:style_emoticons/default/driving.gif)

(IMG:style_emoticons/default/agree.gif) 100%, my 2056 runs great with twin 40 IDF's with 28mm venturis, Gets very good MPG also