cis FD fuel variance per cylinder

[gorskined]

Hello all
i was wondering what is an acceptable amount of fuel variance between cylinders?


a little back ground i have a 76 3.0l row turbo everything new or rebuilt.. The motor for the most part is built to stock with an ic and a evergreen k-27 raptor turbo. I am not looking for Hp more interested in drivability and longevity. This will be my fair weather fun driver . I had a few setback but I finally have things sorted for the most part .
so back to my original question the newly rebuilt non adjustable 76 FD has uneven flow between cylinders. I tested by collecting the fuel in glass beaker. Then measured using a 300ml graduated cylinder I rounded the meniscus up or down to the nearest 5ml mark, like chemistry class allover again.
I ran this test with all different flow condition about 20 times over the last few days low flow, high flow and varied flows high to low, low to high. Each test I shoot for collecting about 200ml of fuel .
There is between 15 and 20 ml variance with a 200ml collection , cylinder #6 is always has the highest flow. The test was run with bran new right out of the box injectors. i even swapped around the injectors to see if it made a difference (no difference). the motor runs and sounds great my AFR # are good the WUR pressures are spot on. I have yet to road test the car. I'm concerned with the fuel variance.

Here are a few example of my test results ,so should I be concerned ?

Thanks

....full flow.....high /low.....low
#1..180ml.......225ml.......205ml
#2..180ml.......225ml.......200ml
#3..175ml.......220ml.......205ml
#4..175ml.......230ml.......205ml
#5..180ml.......220ml.......195ml
#6..190ml.......240ml.......215ml

[Alan L]

Porsche suggest within 10% is ok. It is in one of my manuals - but for N/A engines. Personally I prefer much tighter specs for turbo. But if u can't adjust it...?
A lot of people complain of low throttle bucking on CIS engines. Apart from airleaks this is a major cause I am sure.
Alan

[gorskined]

Alan
I wish the extra fuel was on cylinders#2 and 5 from what i was told 2 and 5 tend to run lean because of the intake manifold design . I'm actually going to try and see if i can swap lines 5 and 6 at the FD . If i can't i will run it as is seeing as its only a fair weather driver.

one other thing
just curious in the future could i swap out the early non adjustable FD with a later adjustable FD? is it a simple swap? will it work on my early my cis box??? if so is there a procedure to establish a base line?


Thanks Regards Ned

[Alan L]

Not sure what swapping the lines will achieve.
But u can plug any line to anyFD port.
Dont know if the FDs are interchangeable - but someone here will have done it if possible
Alan

[heliolps2]

Hello there.

I fixed this on two my cars a 930 and a 964 turbo 3.3. see link and pics

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1087830-cyl-2-5-lean-how-i-fixed.html

https://rennlist.com/forums/964-turbo-forum/1239958-cyl-2-and-5-lean-this-is-how-i-fixed.html

[turbo ride]

You can adjust flow to individual lines at the Fuel Distributor

[gorskined]

Originally Posted by turbo ride

You can adjust flow to individual lines at the Fuel Distributor

The early 3.0l Fd are not adjustable. like the later 3.3lfd

[gorskined]

Originally Posted by heliolps2

Hello there.

I fixed this on two my cars a 930 and a 964 turbo 3.3. see link and pics

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1087830-cyl-2-5-lean-how-i-fixed.html

https://rennlist.com/forums/964-turbo-forum/1239958-cyl-2-and-5-lean-this-is-how-i-fixed.html

yes this is the article i was talking about how 2and 5 run lean. i wish the fd on the 3.0l cars were adjustable ..... i was able to swap out my fd lines at the fd so the 2 and 5 have more fuel... .. going to run it for a while and retest.

[gorskined]

Originally Posted by Alan L

Not sure what swapping the lines will achieve.
But u can plug any line to anyFD port.
Dont know if the FDs are interchangeable - but someone here will have done it if possible
Alan

Alan
seeing as cylinders 2 and 5 get more air and tend to run lean if my fd is not perfectly balanced. it would be best to have the most fuel going to cylinders 2 and 5 . i was able to swap the lines at the fd now cylinder 5 gets more fuel than 6 ... btw the car runs and pulls really nice thanks for all your help .

[krasuskyp]

Great to hear you're on the road there Ned, and that your lines swapping experiment worked. I'd say you're good to go, esp for a street car.

Let's meet up sometime - would love to check yours out. I'm heading to the FCP Euro show Sun a.m. @ Lime Rock w/ some others if you wanna join...

[turbo ride]

Originally Posted by gorskined

The early 3.0l Fd are not adjustable. like the later 3.3lfd

Did not know this - my bad. Learn something every day.
But that's a real bummer...

[gorskined]

Originally Posted by krasuskyp

Great to hear you're on the road there Ned, and that your lines swapping experiment worked. I'd say you're good to go, esp for a street car.

Let's meet up sometime - would love to check yours out. I'm heading to the FCP Euro show Sun a.m. @ Lime Rock w/ some others if you wanna join...

Sounds like fun but I'm not 100 percent legal at the moment working on getting it registered its a Belgium import car. brought it for a vin verification yesterday and the dmv computer kept kicking it out .. Think i may have some hoops to jump through.
defiantly need to get together for some driving once I'm legal. my only saving grace is that it was titled in Florida 25 years ago and i have that title and the original registration. been on and off the phone all day with the department of motor vehicles.

[krasuskyp]

Ugh - what a PITA... good luck / gitrdun! 8 )

LMK when no longer runnin dirty and we can meet up...

[gorskined]

does any one sell or make new hard fuel lines???? The 6 that go between the fd and the injectors. also are the 3.3 and the 3.0 lines the same?

Thanks in advance