speedtigger

iTrader: (16)

I was playing with idle AFR today and my car drives better and the idle sounds better at 11.1 to 11.2 air fuel ratio. I tried it leaner but she is just not happy up there.

What are you all setting yours at?

3pedals

iTrader: (3)

mine drives better set rich as well, cant remember the numbers. I dont think the numbers really matter, just give it what it wants.

S10xGN

iTrader: (11)

I ended up with 12.2 AFR at idle. Any leaner and it wants to stall when either the PS or A/C sees any load. Even at that, the turn-downs leave perfect black smoke rings on the cement!

xpndbl3

iTrader: (23)

I'm in the 15:1 A/F ratio range with my camaro. Of course I'm running 28 degrees timing at idle, which will clean up the a/f ratio quite a bit compared to if I'm only running 20 degrees or so. So what are your guys idle timing at? 11:1 is extremely fat, and sounds off to me.

3pedals

iTrader: (3)

I'm at 38* from 500rpm to 3000, then dropping off to 32-33*. it doesnt care where the upper rpm timing is, between 32-37*, and Ive tryed each setting.
It seems to like aggressive timing bellow where the cam is happy

speedtigger

iTrader: (16)

I took an old 650 Mechanical Secondary I bought off of E-bay, rebuilt it and put it on the car today. Viola! I can set the idle at any AFR I choose and no hesitation at tip in. It cruises between 13.5 at 14.2 and WOT is between 12.2 to 13.1 depending on the situation but generally settles in at 12.4. There is no bog, no hesitation and it drives like a dream. I did not have to change jets, bleeds squirters or pump cams. It works perfectly just as calibrated from the factory.

What is wrong with the Pro Systems carb? I suspect maybe the idle transfer slot is not working. Patrick wants me to send it in so he can have a look. I may pull the base plate first and just check to make sure the idle transfer slot is machined right.

While it is hard to tell by seat of the pants, the 650 does not feel as strong as the Pro Systems carb and the throttle response is not a violent either. So, I will say that I think the Pro Systems carb definitely makes good go fast, it just has some other metering system problems.

Either way, it is good to see the car run so well and so clean around town. Too bad my exhaust system, plugs and combustion chambers have accumulated so much soot running the other carburetor. It is also nice to sit at a light or pull into the garage without choking to death on hydrocarbons. All in all, Happy Day.

Paul57

Nice to hear that you made some significant improvements. Is the 650 just a "standard" stock carb?? I was surprised that you had AFR issues with the dual plane. I have the same intake and am keeping my fingers crossed when I use the 750...although it is an Edelbrock carb.

thirdgenbum

iTrader: (17)

i'm at bottom 16's idle, mid-bottom 12's at WOT, and bottom 13's under mild acceleration.

tuned by plug readings and max 1/4 mph only. stuck the wideband in mearly to see where i was at. no adjustments were made after the wideband was put on the car.

speedtigger

iTrader: (16)

It is a just regular old 4777-3 I bought on ebay for $75. It still had all the factory jets and calibration. I merely filed the flat surfaces and threw a kit in it. Once I saw how nearly perfect all the a/f ratios were at idle, cruise and WOT, I knew I had to send the Pro-Systems carb back to Patrick for some love.

I also ordered a Holley 750 HP conversion kit for the 650. We shall see how well that works.