My frankenstein project of putting a Holley 5200 off a 73 pinto on my slant has hit a big snag.

When I start it up (all ignition parts are new, I used warrantys) it idles weird.

Brrrrrrr buh brrrrrrr buh brrrrrr etc....

The fuel mixture screw appears to have no effect on idle what so ever.

What could be causing this? Would a large vacuum leak cause this weird phenomenon? I went down Idle Jet sizes .50 to .45, same thing happening.

Help!

Tim

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My Swinger gets the Highlight Valet Parking spot over the German sports cars on the Sunset Strip. I love my Mopar.

Can you get it to idle better by partially closing the choke flap?
DD

No, at least the choke opening and closing has no discernable effect. If it did effect idle what would that mean? I will mess around with it a little

Somebody floated the idea of amy float being maladjusted (No pun intended). Is there any validity to this hypothesis? It is adjusted to specs for a 2.3 L Pinto engine. Should I have it floating higher and dropping lower? or higher and higher? Or lower and lower?

Thanks for all the help, Frankenstein will appreciate it.

Tim

_________________
My Swinger gets the Highlight Valet Parking spot over the German sports cars on the Sunset Strip. I love my Mopar.

Before we go any farther, we need more info.
How does it run otherwise; cruise, accel, WOT, etc?
What kind of ignition is it; points, oem electronic, pertronix?
How did it run before this carb was installed?
Did you change a whole mess of parts all at once before this problem started?
Is everything else stock? Which manifold? Adaptor?

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"A mechanic is Somebody."
- Jim Preston

225 Slant, auto trans w/ Shift Kit, 1970 Swinger, stock exhaust.
stock engine, 73 electronic ignition, (Cap Rotor ECU Distributor Coil All new, 3 year old wires, 8 month old plugs
Power Steering, A/C Removed
Holley 5200 of of 1974 2.3L Pinto, Rebuilt with Tomco Kit, set to 74 pinto Specs. Custom Jetting (what other slanters are using) is 180 Mains, 180 Air Correctors, .45 Idles
Single bbl intake, TransDapt 2050 2bbl to 1bbl adapter, modified to include a PCV port (1/4" NPT Barbed Hose Fitting)

Ran great with Holley 1920 and a #61 Jet. Timing at 8 BTDC.
When I take it around block with new setup, (Farthest I will go without vac advance hooked up or kickdown attached) It does not stall on me, but I have the idle adjust higher to prevent that. I have all the vac ports plugged except PCV. which is attached. At wide open throttle the miss, stumble or whatever you call is way less noticable, almost unoticable.

Hope that is enough info.

_________________
My Swinger gets the Highlight Valet Parking spot over the German sports cars on the Sunset Strip. I love my Mopar.

Maybe you need to increase the dosage of immune supression drugs...after all, it's a F**d carb!
Sorry, I'll behave now.
Closing the choke per Doc's post would richen the mixture, compensating for a vacuum leak/lean jetting situation. Since that doesn't help, and the miss stays (more or less) during operation, and it sounds like a regular miss, I'd look back through the ignition system.
Lean conditions tend to cause irregular, random missing. Yours sounds like it's rythmic, cutting off like turning the switch on and off. New/reman distributors give a lot of trouble, so don't rule out stuff just because it's new.
Check your basic wiring, control box ground, ignition switch, etc.
I personally don't like 2-1 adaptors, they can mess up your flow.
Stock Pinto jetting might be lean on a slant, but I'm not familiar with those carbs to translate the jet numbers.
Sorry I can't say more; long distance diagnosis is tricky at best.

_________________
O==\=/==O

"A mechanic is Somebody."
- Jim Preston