Weber 44 IDF's - keep - or find original d-jet? Options

[Gatornapper]

Questions re: Weber 44 IDF carbs:

1. Is anyone running these on a stock engine, and if so, how do they perform? National Carburetors kit for stock engines is 34 ICT's, lightly modified 40 IDF's, and only 44's on heavily modified engines.

2. What problems do you introduce using 44's? other than dumping too much fuel in the engine......

3. Venturi's are 45mm, someone pointed out that one should use 40mm venturi's - is that with a stock engine?

4. Anyone run 44's and then convert back to EFI? How did that go? Labor cost?

TIA,

GN

[Bleyseng]

All this badmouthing Djet, bah. Its a simple system, runs better than carbs as that's why Porsche used it.
Problems are the FI wiring harness which lays on the hot engine and gets brittle with little shorts in it. Get a new harness.
Problem #2 is the MPS blows out making the car run rich, really rich. New diaphragms are available now and the MPS is easily calibrated to stock.
Problem #3 is the CHT goes out and the engine runs super rich. This is the ONLY failure I have had with Djet since 1998 and it happened in my driveway.
I had 40 Dells on my car when I bought it and 1995 and had soo many problems with them. Keeping them in sync, cold starting was a hassle, etc. Run great at full throttle but who drives around at full throttle?

The stock Djet 2.0L throttle body is 45mm.

[Gatornapper]

I have never badmouthed D-jet, and up until recently when I finally got the 44's dialed in, considered it an option once the solid internals of the engine itself was established.

I am good with carbs, and have been doing them for over 50 years, although Weber's are new to me - now I really like them.

Totally understanding the limitations of a cam for FI without the lift or duration needed for carbs, I still can't understand how the air from 4-36mm venturi's can be matched by the air through one 45mm throttle body......but my old memory thought I measured my '76 D-jet system as having a 34mm throttle body.....all packed away nicely now, but I may just unpack it to re-measure it again. I may be wrong. Won't be 1st time, won't be last.

And no question FI is better than carbs overall....hands down. First worked on them in 75 on a '72 Volvo.....loved the system.

One other question: have I heard incorrectly that the ECU's often go bad, and good rebuilt ones are very hard to find? I think even Eric at PMB told me that, and strongly advised me to not put the D-jet in the car.

GN

All this badmouthing Djet, bah. Its a simple system, runs better than carbs as that's why Porsche used it.
Problems are the FI wiring harness which lays on the hot engine and gets brittle with little shorts in it. Get a new harness.
Problem #2 is the MPS blows out making the car run rich, really rich. New diaphragms are available now and the MPS is easily calibrated to stock.
Problem #3 is the CHT goes out and the engine runs super rich. This is the ONLY failure I have had with Djet since 1998 and it happened in my driveway.
I had 40 Dells on my car when I bought it and 1995 and had soo many problems with them. Keeping them in sync, cold starting was a hassle, etc. Run great at full throttle but who drives around at full throttle?

The stock Djet 2.0L throttle body is 45mm.

[914_teener]

I have never badmouthed D-jet, and up until recently when I finally got the 44's dialed in, considered it an option once the solid internals of the engine itself was established.

I am good with carbs, and have been doing them for over 50 years, although Weber's are new to me - now I really like them.

Totally understanding the limitations of a cam for FI without the lift or duration needed for carbs, I still can't understand how the air from 4-36mm venturi's can be matched by the air through one 45mm throttle body......but my old memory thought I measured my '76 D-jet system as having a 34mm throttle body.....all packed away nicely now, but I may just unpack it to re-measure it again. I may be wrong. Won't be 1st time, won't be last.

And no question FI is better than carbs overall....hands down. First worked on them in 75 on a '72 Volvo.....loved the system.

One other question: have I heard incorrectly that the ECU's often go bad, and good rebuilt ones are very hard to find? I think even Eric at PMB told me that, and strongly advised me to not put the D-jet in the car.

GN

All this badmouthing Djet, bah. Its a simple system, runs better than carbs as that's why Porsche used it.
Problems are the FI wiring harness which lays on the hot engine and gets brittle with little shorts in it. Get a new harness.
Problem #2 is the MPS blows out making the car run rich, really rich. New diaphragms are available now and the MPS is easily calibrated to stock.
Problem #3 is the CHT goes out and the engine runs super rich. This is the ONLY failure I have had with Djet since 1998 and it happened in my driveway.
I had 40 Dells on my car when I bought it and 1995 and had soo many problems with them. Keeping them in sync, cold starting was a hassle, etc. Run great at full throttle but who drives around at full throttle?

The stock Djet 2.0L throttle body is 45mm.

Do what you know:

But know this...just because a carb has a certain size opening does not mean the engine will make more power. Power is express by the VE curve which is short for volumetric efficency. The reason the automotive industry went to FI was because it is simpler and more efficient to make power.

I think any FI system is easy to understand...they all work pretty much the same way. Porsche along with Bosch did some amazing things with it going back all the way to the Messcherschmidt in aeronautics in WW2 as you may know.

You may have heard wrong. The ECU in the 914 is very robust and hardly ever burns out. They can be tested and fixed there are a few companies that do this.

A Good read on induction with carburators. https://mooregoodink.com/induction-science/

This is no simpler to do that setting up an FI system. Really it's just a matter of money. Eric does good work and is a good business person.

With regard to your 050 dizzy. There are better electronic replacements I think and if you like and spending time on those types of things then...that's okay do that.

I'd rather drive the car then tinker and wonder why it's "better". But that's me.

Good luck on your journey.

[Gatornapper]

914 Teener-

Of course you are accurate on your first paragraph.

As to my D-Jet:

DrPhil has been incredibly kind in testing my ECU, MPS and TPS in his car. ECU is fine, TPS needed cleaning, is fine. MPS needed a Tangerine rebuild kit which he graciously put in. All I need now is to have injectors tested, get new wiring harness and plumbing.

As to my carbs:

I studied Bob Tomlinson's "Weber Tech Manual" - Super Tune-Up Guide for VW and Porsche Engines. That and the grace of God are what helped me get my 44's dialed in.

There is a Table "Weber Jetting Guide for Air-Cooled VW Engines on P. 64. Jetting for Dual IDF 44's in a 2000cc engine says:

Venturi: 36mm - Mine: 36mm
Main: 155 - 180 - Mine: 135
A/C: 2.00 - Mine: 2.00
E/Tube: F11 - Mine: F11
Idle: .60 - Mine: .60 (Car came to me with .50's, but I could not get a good idle with them.
P/Jet: .50 - Mine: .50

Another item helped carb performance: Pump bypass valve normally has 50% return to float bowl. Mine have 0% return, with 100% of fuel going into the throats. A Weber expert recommended this.

Took my car yesterday to a member in Virginia who is a top expert in VW engines having built and raced them for years, who also has a 914. He drove it. He said my idle is as good as it gets, and gave my carb performance an A. Made my day.

As every 914 owner who has driven my car has said, it is amazingly tight. I am grateful.

As to my 050 Dizzy - amazing improvement in engine power and performance from 009 that was in car when I got it. Night and day. Be nice some day to get a 123, but they are expensive. I am running Pertronix ignition in the 050.

Hope this may be of help with anyone else running Dual IDF-44's on a 2.0 engine.

GN

Do what you know:

But know this...just because a carb has a certain size opening does not mean the engine will make more power. Power is express by the VE curve which is short for volumetric efficency. The reason the automotive industry went to FI was because it is simpler and more efficient to make power.

I think any FI system is easy to understand...they all work pretty much the same way. Porsche along with Bosch did some amazing things with it going back all the way to the Messcherschmidt in aeronautics in WW2 as you may know.

You may have heard wrong. The ECU in the 914 is very robust and hardly ever burns out. They can be tested and fixed there are a few companies that do this.

A Good read on induction with carburators. https://mooregoodink.com/induction-science/

This is no simpler to do that setting up an FI system. Really it's just a matter of money. Eric does good work and is a good business person.

With regard to your 050 dizzy. There are better electronic replacements I think and if you like and spending time on those types of things then...that's okay do that.

I'd rather drive the car then tinker and wonder why it's "better". But that's me.

Good luck on your journey.