Looking for easiest way to know 2x4 linkage is adjusted correctly.

[Wheels427]

Engine runs well ,except seems to run a little rich,just wondering if carb linkage is adjusted properly.If it matters I'm running 470 Holleys on Bluethunder med. riser intake.On 427 .Thanks.

[ted]

I'm assuming you have the staggered carbureter linkage where the car drives off of the front carb in low throttle situations and the carbs are installed backwards on the intake. Try closing the idle to almost "nill" on the rear carb with the idle mixture screws turned one turn out. You want the rear carb throttle plates almost fully closed but cracked open just enough that they will not stick. Then idle the engine off of the front carb and reset the front carb idle mixture screws for best idle and see if this cleans up the "richness".

If your linkage is such that both carbs are working simultaneously all the time, then disregard what I just said.

[SCOBRAC]

running rich on a Holley won't be caused by the linkage. There are idle screws on either side of the primary fuel bowl (closest to the firewall) which primarly control idle mixtue. 90 % of all holley's are leaned out by screwing the idle mixture screws in.

What you do to one you should do to all 4 screws. If the idle mixture doesn't change when you a adjust the screws in your fast idle settings are wrong. In cases like that you are running rich by actually idling with the low speed idle transfer slots partially exposed.

The best place to begin is by ting t lean it out by using the idle mixtue screws. Let us know if that works.

[Michael C Henry]

I suspected my carbs of running rich and fouling my plugs.I had my 1850 Holleys redone by Quick Fuel Technology. I was instructed to open the secondaries a little so as to close the primary transfer slots . It now runs great but the carbs turned out not to be the culprit .It was the Ignition box crapping out. I finnally bypassed the ignition box and without cleaning the spark plugs it ran fine and has kept on running flawless . I suspect the air cleaners of being restrictive.The foam in the Stelling &Helling aircleaners.I'm looking at other allternatives,I have hood clearance problems and want to get air from the hood scoop.

[Wheels427]

Thanks guys,I'll try your ideas out as soon as we get soon decent weather,We are in the midst of a rain/snow/freezing rain mess right now. This week is supposed to get a lot nicer ,so I'll experiment then.Thanks again.

[SCOBRAC]

I'm not familliar with "470" Holley's. Holley presently makes a 390 and 450 mechanical secondary 4160 style carbs. Are the 470's vacuum secondary units?

Chances are they are equipped with an 8 or 8.5" pover valve. Check your manifold vacuum at idle. The power valves should be 3" (inches of vacuum) lower than the manifold vacuum at idle.

Example. If your car idles at 6-7" of vacuum you should have a 3-4" power valve in each carb or the power valve will open prematurely or even be open at vacuum creating a rich condition at or just off idle.