Porsche 911 Project

[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..?

[e30austin]

Love it.

[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

[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]

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.

[LJ851]

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

[ohthejosh]

Great stuff

[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]

[rikaro]

always love the look on a wingless 911 coupe

[LateFan]

Yeah, I like this era with no wing. That looks great - black is good, wheels are good, the height is good. Very nice.

I have a friend with a 60s 911 with old Zeniths, and they leak fuel and idle way too rich and pop pop.

[88M3racer]

I enjoyed your build thread ...

Being here in the Atlanta area some things I could understand 100%.

I've taken on a similar, yet BMW. project & am bring it back to life.

Keep driving ... and hope to see you out on the roads.

[AudioNToxication]

You can get the accel pumps to come online sooner, the have some adjustment or you can talk richard into selling you a set of the "hatchets" that drive the pump plunger to shoot more fuel in.
In reality due to it being air cooled and somewhat of a inefficient combustion chamber 12.5 is probably a better number to shoot for at full throttle.

[LJ851]

You can get the accel pumps to come online sooner, the have some adjustment or you can talk richard into selling you a set of the "hatchets" that drive the pump plunger to shoot more fuel in.
In reality due to it being air cooled and somewhat of a inefficient combustion chamber 12.5 is probably a better number to shoot for at full throttle.

I already have the hatchets from Richard and they did help, but not enough to get my light throttle AFRs to a reasonable number. The car drives very well by seat of the pants, i just don't like knowing its so rich in places.

[2mAn]

whatever happened to the megasquirt this was running when you bought it?

[LJ851]

whatever happened to the megasquirt this was running when you bought it?

The megasquirt on the car was 911 specific kit to replace the CIS injection and i sold that pretty early on.