Weber 40 IDF settings for 1.7 ?

[atomman]

Hello

I have a quick question, my 914 has a 1.7 engine and the fuel injection is shot, I have a pair of 40 IDF to fit but dont know were to start with venturi size and main jets etc ..

any one give me a 'basic' set up to start with ?

I have the use of a dyno to fine tune it, but just need a starting point really

Cheer

Gary

[Piledriver]

Welcome to the STF!!!

What jetting etc do you have?

Unless jetted for a really radical motor, it's probably already at a good starting place if the carbs are freshly rebuilt.
I ran 44IDF/36 vents on a stock 1700 with almost baseline jetting with no issues for ~100k mikes before installing CIS mostly due to CIS being ~bombproof.
BUT--- Define "shot" Re yout EFI.

There is very powerful L-jet and DJet-fu lurking over in the STF Fuel Injection forum.

It's a relatively simple FI system, and generally easy to troubleshoot//fix, no weird test equipment or computer needed.

With the FI running right, the Webers only advantage is they look/sound cool.
They have their own headaches. Strongly consider Jet Doctors, and keep your rain tray or buy/make rain hats.
Plan on a new fuel pump and pressure regulator, and strongly consider replacing the fuel lines in the center tunnel with steel regardlwss of what you do otherwise---
the ~40 year old plastic lines are done, trust me.
Fire Bad.

If you still want to ditch the EFI, do NOT trash ANYTHING, as the manifolds etc work ~perfect with other FI systems on T4 or are spares for someone else.

[atomman]

Hello piledriver

Im sorry for the short first post I should have intruduced myself first.

My name is Gary and I live in south wales, I have spent the past 4 years restoring a '65 912 and sold it about 2 months ago and soon after missed a porsche so came across a 914 in my mates barn, It needed a bit of work on the hell hole but wasn't that bad, so a deal was done and it was mine.

The engine had been siezed so it came with a '70 1.7 lump with fuel injection and loads of extra wires plumbed into the loom. I have no idea about L-jet injection apart from it is missing the fuel pump and the air mass meter ? that is on the side of the engine bay, and loads of extra wire have been spliced in for some reason.

Its not easy to get spares over here in the UK as there aren't many 914's about or type 4's, so i borrowed some 44idf's of a friend and put these on to get it going, I have brought some 40 IDF's from over there that are currently winging there way over to me, so i dont know what jets etc they have on them but they have came off a 1.7 914 so should be a good start.

I was just wondering if there was a base setting to get started with ? i could just look what jets they have and start on the dyno from there i spose.

Anyway's heres the car in question from the other weekend out with a fe mates for a sunday drive










cheers for the help

Gary

[DWP]

Gary
you might want to look around here
http://forums.pelicanparts.com/index.php

Dig around the tech section for wiring help ect.
If you do put on the webers you are going to need a new fuel pump. and or regulator.
The fuel pressure should only be 2 -3 pounds.
also find a copy of Weber Tech Manual, by Tomlinson
Dave

[Piledriver]

Excellent 7th post, Gary!!!

We have lifers around here that can't seem to manage to successfully post pictures

Beautiful teener, they are great little cars if you can beat back the rust monster and keep them maintained.

To echo the fuel pressure issue--- The Webers turn into really "bad FI" if you exceed their fuel pressure holding ability. using the FI pump to feed it is a fire waiting to happen, even if you put a non-return regulator in.

L-jet is nearly bulletproof (by comparison to DJet... and even the Webers) and aftermarket harnesses are available--- It's usually what is wrong.

I understand the parts thing, and no one will gripe at you here for installing the Webers.
(but the FI is so much better on a stock motor, working right)

[atomman]

The car has run carbs before so it has a Facet (I think) pump up front, I've checked the pressure and it's alright for now.

The 44's are a bit big for the 1.7 i think, they have 42 venturis in them and the car doesn't really get going below 3k,but they are not mine so cant muck about with them really, so cant wait for my 40's to turn up to have a play around.

Dont worry I have the FI stuff in a box and I have been looking at MegaSuirt etc..

I am in the process of getting parts together to build a bigger engine I have some 2.0 heads, not 914 though, and a 2.0 crank and rods and case.

Was planning on getting some 103mm B+P's and cam, porting,flowing and polishing heads,

I really want an engine with low torque over out and out race engine, but i need to do alot more research and reading up about type 4 engine

any recomendations for after market FI management systems ?

[Piledriver]

The car has run carbs before so it has a Facet (I think) pump up front, I've checked the pressure and it's alright for now.

The 44's are a bit big for the 1.7 i think, they have 42 venturis in them and the car doesn't really get going below 3k,but they are not mine so cant muck about with them really, so cant wait for my 40's to turn up to have a play around.

Dont worry I have the FI stuff in a box and I have been looking at MegaSuirt etc..

I am in the process of getting parts together to build a bigger engine I have some 2.0 heads, not 914 though, and a 2.0 crank and rods and case.

Was planning on getting some 103mm B+P's and cam, porting,flowing and polishing heads,

I really want an engine with low torque over out and out race engine, but i need to do alot more research and reading up about type 4 engine

any recomendations for after market FI management systems ?

Wow, slipped through the cracks, thought I had responded...

Megasquirt is a good place to start looking, you can buy pre-built systems to order, or fully DIY.

I'd reconsider the 103 P&L if it's going to be a driver, but they might go awhile where you live.
Keeping the bore down and upping the stroke is usually a better plan due to head sealing issues.

A big motor needs big heads... price increase is disproportionate to performance boost, and not in a good way.
GOOD head work costs real money, lots.
Just be advised.

42 vents are HUGE, 36s were std, I ran a 1700 for a long time on 44IDF/36 setup.
The only thing "odd" about the tuning was I ran ended up with 70 idle jets (much larger than suggested), screws were <1/8 turn from closed and the setting was touchy.
(it worked very well though, transition smooth and fuel economy excellent)