Hi, I hope u guys can help me,me problem is when i punch the gas my holley carb burps fire, the engine is newly rebuilt and i have not had a chance to take it on the road yet,
so its not broken in all the way yet,any way
here what i have in it, if this helps some,the carb i a holley 0-3310(4150) 750 CFM
also when the engine is running it has a vary rich exhaust and a little black smoke is coming from inside the valve covers, my cam shaft is the Magnum kit from Comp Cams
it has a 470" lift and a 224 degree duration,
my comresshion is 9.35:1,my intake manifold is the edelbrock peformer RPM air-gap, my cyinder herd are GM HP with 2.20/1.60 valves,i have headers and a 2'1/2 inch flow master american thumder system. i checked my vacum and it reads to 12, but it does not hold study at 12. could it be from a bad cam ?

If you get fire back thru the carb, an intake valve has to be open when the cylinder fires ... Take another look at your timing ... address the fire issue first ... then in terms of being rich, use a vacuum gage to adjust the carb ... was the carb rebuilt also ... are you using a PCV ? If carb was rebuilt, check float level and power valve you are using ... You may need to jet down ... You'll probably need to pull and clean your plugs if car was running super rich ...

Depending on the Age of this Holley it may not have Power Valve protection. It usually only takes 1 good Backfire thru the carb to Blister it, as Posted previous Check Timing make sure its correct, Check Float lvls. I would also pull it down and Not take a chance on the Power Valve and Replace it also. But thats just me.

I had the same problem with my reman motor and Holley carb.(10 foot flames) I reset the timing and it cured the problem.

i bought my holly new in the summer of 2000.
my timing is set a 8 degrees,is that right?
i went by the GM factory specs.
thank guys for your help.

<BLOCKQUOTE>quote:</font><HR>Originally posted by 72'camaroguy:
i bought my holly new in the summer of 2000.
my timing is set a 8 degrees,is that right?
i went by the GM factory specs.
thank guys for your help.<HR></BLOCKQUOTE>

That sounds a little on the low side to me. I would take it up a couple of degrees and see how it responds and then check to see where your vacuum is at then it might be a little higher.

72, one other thing comes to mind ... Make sure you have spark plugs wires on the cap correct. If the wire is in the wrong position, you can get a backfire thru carb ...

Aren't the magnum cams solid lifter type. Could the adjustment be off on the valve lash holding a valve open??
Just trying to help here.
Still look at the timing first though.