carbed 454 mag will not idle
 

Changed the ignition and checked everything. It seems really lean even with the idle mixture screws turned out. All the plus are dry and it will not idle at all

Carb is a 800 holley with an edelbrock single plane intake. Just swapped over to a roller cam.

Valves/rockers adjusted too tight will cause that.

Ignition timing being way off will cause it.

Could be dirty carb also

I bet you slipped an intake gasket and you're sucking air from the crankcase.

start with the basics,make sure the timing is set correctly and also check the float levels.

Griff you were right. We set the lash at a 1/2 turn and had to back it off to zero and it ran good. Does anybody know what the spec is on ISKY hydraulic tie bar rollers?

It should have been fine at 1/2 turn past 0 lash. I have a feeling your valve adjustment procedure might have been done incorrectly.

I see you converted to hydraulic roller. You are using an adjustable valvetrain setup now with polylocks correct?

When adjusting the valves, you must be sure the plunger isnt collapsed in the lifter. What I do, is rotate the engine until the #1 Exhaust valve begins to open, then I adjust the #1 Intake valve. Then, rotate again, until the #1 intake opens fully, and is almost closed, I do the #1 exhaust valve.

The carb needs vacuum to draw fuel from the idle circuit. Cant create vacuum, if the valves are hanging open from being adjusted to tight. A true 1/2 turn from 0 lash, with the lifter on the heel of the cam, SHOULD NOT cause the valves to hang open. Something else is going on.

I know Maine is a big state, but gotta' ask because I may be able to help if you have time, how close are you to Lake Winni in NH ?

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Besides that, everyone above is correct.

With todays schit (ethanol fuel) it's very likely you have some crap in a fuel circuit. Also, very likely some dust even can plug an air bleed at top of the venturis in a Holley. Normal maintenance is to point red plastic nozzle right at/touching each air bleed with the mixture screw out of carb. Spray in air bleed, then spray in mixture screw hole, then do it back and forth a handul of times. Watch your eyes ! That idle bleed hole is pointed right at them and carb cleaner hurts bad for a few !

One thing missing, is on the subject of a Single Plane intake manifold.

#1: it likes more initial timing. The intake stays cool #1, and #2 reduced signal to carb, and #3 cross talk between cylinders during overlap.

#2: Carb idle circuit needs to be richer for same reasons as above.

Furthermore, most lifters are totally fine up to a full turn.

I do it as MT does it with the finger spin technique to know when at 0 lash.

Just thought of something, speaking of which, whick f*ks up a lot of people.

When you adjust a valve with a hydraulic, count it done. Do not come back to it once tightened !

Why ? The lifter may collapse a little and when when you recheck it the pushrod will spin freely,,,so,,, you think you didn't do it right so you adjust down more. This is bad ! The lifter collapsing fooled you into thinking you didn't turn it down enough. You finally fire the engine and , yup, they pump up and your valves aren't closing fully and wallah, it runs like dogschit.