Porsche 911 Project

[rikaro]

always love the look on a wingless 911 coupe

[LJ851]

Not a lot has changed on the car recently, just driving it a lot. I had 15 inch wheels on it for a while and the ducktail has been on and off twice. I finally got some street tires in the sizes i wanted for the 16 inch wheels and lowered the front a little.

Current pic


[IMG][/IMG]

[ohthejosh]

Great stuff

[LJ851]

Went up to Road Atlanta for the fall vintage races, parked next to some fancy cars.

[LJ851]

Could be the idle circuit.
Here's a good trouble shooting write up that focuses on the IDA's.

http://www.jiminglese.com/weber5_005.htm

With a smaller idle main jet and larger idle air jet i can create mid-upper 13 AFRs at part throttle which is great but it gets really hard to start (no chokes) and it creates a big lean flat spot on tip in. Also tons of backfiring through the carbs on transitional throttle.

I feel like if i can get the accelerator pumps to kick in a good bit sooner i could make those idle jet settings work.

From what i understand, the cams (motronic) are part of the problem with their very small overlap numbers. The carbs are just not designed for that.


Thanks for the link.

[Good & Tight]

Right now i would say average light throttle (cruise) is 11 to 1. The smaller the throttle opening, the richer it is. If you just tip into it, it is down in the high 10's and before i get to 1/4 throttle it is back into the 12's.

Could be the idle circuit.
Here's a good trouble shooting write up that focuses on the IDA's.

http://www.jiminglese.com/weber5_005.htm

[LJ851]

The joys of changing carb jets. How rich at light throttle..?

Right now i would say average light throttle (cruise) is 11 to 1. The smaller the throttle opening, the richer it is. If you just tip into it, it is down in the high 10's and before i get to 1/4 throttle it is back into the 12's.

Something new i have learned is that motronic cams are not what the carbs are designed for and the lack of overlap is a contributor to my issue. A set of cams with decent overlap would probably make it run and sound noticeably better.

Love it.

Thanks, Austin

[e30austin]

Love it.

[Good & Tight]

Been driving the 911 a lot and doing jetting changes. I've made good progress and currently have a setting that has good throttle response, doesn't foul plugs and has a good full throttle profile.

It's current fault is that it runs super rich at light throttle and i haven't been able to address that without causing an unacceptable compromise is throttle response.

My drivers side door handle trigger just broke so i need to fix that too.

The joys of changing carb jets. How rich at light throttle..?

[LJ851]

Been driving the 911 a lot and doing jetting changes. I've made good progress and currently have a setting that has good throttle response, doesn't foul plugs and has a good full throttle profile.

It's current fault is that it runs super rich at light throttle and i haven't been able to address that without causing an unacceptable compromise is throttle response.

My drivers side door handle trigger just broke so i need to fix that too.

[spiDmang]

so jealous of this...and duckbill gets my vote :up:

[LJ851]

A crapload of carburetor jets are on the way to me from PMO. Woooooo

[4Running Daily]

Duck tails do it better

DSC_0114 by Connor Rhoades, on Flickr

[LJ851]

Duck tail is back on, i'm enjoying that.

I've been driving around with my wideband 02 hooked up. My suspicions about AFRs were pretty much on point.

Full throttle is a little rich and fades richer at high rpm.

Light throttle is Very rich, like 10-10.5 to 1.

There really aren't any wild fluctuations in the AFRs which is nice, I'm hoping some simple jet changes will get me an acceptable fuel curve without creating any new issues. We will see.

LateFan, the carbs are pretty much brand new so i just sprayed them down with Berrymans carb cleaner.

Going to put in an order for a selection of carb jets today.

[Staszek]

Just read this thing all last night. Awesome project!