Engine stumbles under lateral g load. Carb issue? - Page 2

WBofTN · #21 (**permalink**) 08-04-2003, 02:10 PM

thanks Mr Fixit - i just printed your info and will check it out
tonight.
WB

Curt C. · #22 (**permalink**) 08-04-2003, 06:46 PM

I have 351W standard bore and stroke, AFR 185's, Holley 750 race DP and a cam with the following specs: 236/246 duration; 520 / 538 lift. No question, the idle is a bit fat, but it appears that the motor likes it there. Motor runs great at speed with about a 13:1 A/F ratio. If I lean the idle out, I get a lean bog condition. I tried putting a 650 demon on there, but could not get it to run rich enough. I believe the cam has something to do with it. The motor will only pull 8 lbs. vacuum at idle - max. This is where it is supposed to be per FRPP. The motor is the 385HP sportsman model with AFR heads added on. The carb is recomended by Ford. Engines makes 377 RWHP.

WBofTN · #23 (**permalink**) 08-05-2003, 08:27 AM

curtC:
Do you hapen to know how many turns out you have your
idle screws set? And does it run rich?

Mr Fixit:
I check my idle screws last night and they were turned out approx
5 turns. I reset them to a/b 2 turns and was able to set the idle
down some - seemed to be idling alot smoother with less smoke.
I was unable to drive the car last night (rain). So I dont know how
these adjustments will effect performance. What should I be watching for?

WB

Mr.Fixit · #24 (**permalink**) 08-05-2003, 08:30 AM

Your idle adjustement is for the idle only. That's all those screws are for, if it idles nicely, good job. The moment you touch the throttle (even a little) you are then into the accellerator pump circuit, and there you have cams and squirters to play with.

Roscoe · #25 (**permalink**) 08-05-2003, 08:34 AM

WB,

Take a look at the site I posted earlier and look at the graph. This will give you a basic understanding on the different circuits. Read the text to give yourself an understanding on what functions they provide.

Roscoe

Curt C. · #26 (**permalink**) 08-05-2003, 05:44 PM

WBofTN

Wow, five turns out is a lot. Mine are about 3/4 of one turn.

Mr. Fixit,

Can you not compensate for a weak squirter / accelerator pump by richening up the idle with the mixture screws? I know this is only a bandaid, but it seems to help the transistion from idle to enrichment circuit.

George Snyder · #27 (**permalink**) 08-05-2003, 06:44 PM

Steve,

Maybe good news & bad news. Good news is that I have a 650 Holley DP 4777c ( mechanical Sec.) that you are welcome to try and if you want purchase real cheap. Bad news is that until I get the replacement throttle plate from Barry Grant, I need to keep using it on the Cobra. I think this Saturday is out of the question. Sorry.
E-mail me if you are interested and we can meet and install it on your car.

Gentilemen,
650 Vs. 750 has been debated for many years. I am not too sure if there is a right answer. There are always alot of variables. Mechanical Vs. Vacuum. Cam, Heads,timing, etc. Maybe mostly trial & error.

Bud

Mr.Fixit · #28 (**permalink**) 08-06-2003, 08:11 AM

"Can you not compensate for a weak squirter / accelerator pump by richening up the idle with the mixture screws? I know this is only a bandaid, but it seems to help the transistion from idle to enrichment circuit."

You shouldn't. what you need to do is play with your accelerator pump cam. Get the kit that gives you a bunch of cams and squirters, try the green cam. Adjust it so it moves the accel pump arm immediately. If the car coughs immediately, bigger squirter nozzle, if it goes than coughs, smaller squirter nozzle (to lengthen pump shot duration) You amy need to adjust the spring loaded accel pump arm "pusher" so it doesn't bind up at full travel.