[ralphiejantz]

Okay I just finished putting a carb swap on an 89 mustang
motor was just freshened new bearing rings etc.
302 cu inches
9.5 to 1 compression
heads are twisted wedge 2.02 intake mildly ported
vic jr. intake mildly ported
.513 lift cam hyd roller
108 lope sep
Pro System 650 carb
manual trans
MSD dist locked advance

before the carb swap the car made a few hp under 300 at the tires on the dyno with a smaller E cam

#1 - Im having a problem getting the idle down on the carb
I would like to get it around 800-900 rpms but every time I turn the idle screws down the car will not stay running at that rpm it just kind of dies out
so Im having a bit of an issue there

#2 - The car gets a bad stumble off of idle Ive played with the carb linkage and everything is where it should be Ive played with the idle screws and adjusted the floats I cant seem to get rid of it,
i know Im probably gonna have to do possibly a squirter change air bleed change jet change or all of the above I just dont know what direction I should be going in up or down with the changes

#3 - Im getting fuel pressure creep sometimes it will creep up to almost 12 lbs and stay up there

fuel system is a magnafuel quickstar 275 pump, filter before pump,
return line from the pump to the tank - 6
feed line -8
regulator is magnafuel 2 port regulator
everything in the fuel system is brand new,
and its getting fed from a stock tank with a sump

any advice is greatly appreciated Ive been playing around with this thing for about 2 days now with no success

timing is locked at 32 deg total timing,

This carb was not built for this motor it was built for something a little more higher hp than what I got but I still think I should be able to get it to work on the motor I have
thanks for any help you can lend

 

[Drag Chevette]

Pro System 650 carb

every time I turn the idle screws down the car will not stay running at that rpm it just kind of dies out

The car gets a bad stumble off of idle Ive played with the carb linkage and everything is where it should be Ive played with the idle screws and adjusted the floats I cant seem to get rid of it,

any advice is greatly appreciated Ive been playing around with this thing for about 2 days now with no success

thanks for any help you can lend

I can tell you what to do to fix your issues, but Im not going to.
not because im being an ass, but because you should have called Patrick first.
It is Patricks carb, he knows his formulas and calibrations, give him a call on his cell and im sure he will walk you through the fix.

if you do not get any help, then ask again.....and someone can help you.

 

[fast 351]

Have you put a vacuum gauge on it to see how much vacuum it's pulling, If so what's your vacuum reading?
What size power valve is in the the primary metering block?
If your gettting a stumble off idle you should go up in size on your primary pump shooter.You may need either more inital pump shot or pump shot over a longer time, Your combo sounds like a street machine So go with the bigger pump shot first. If you still have a bog betwen idle and main jets see if going on the mains help. You stated the carb was for a bigger engine you may have to bring the main jets down. I can tell you that with the advance lockout it's hard to get one to idle properly. This should be enough questions and input to get you a good base line as to what needs to be checked for now. Let me If I can help any further...Tony