69442

My '72 Cutlass Supreme has the original rebuilt 455 engine w/ less than 500 miles. The engine is bored .030 w/ TRW L2323F forged pistons, (approx 9.5 compression), stock GA heads w/ roller rockers, Mondello 20-22 camshaft, Pertronix ignition, stock intake manifold w/ NOS 1970 Quadrajet # 7040251, stock W/Z exhaust manifolds w/ 2 1/2" dual exhaust, Thornton W-30 OAI set-up, 3.42 rear end gears w/ 275/60 tires. I am also running 93 octane fuel. I have adjusted the total timing a couple of times and still have pinging at part throttle and worse at W.O.T. The car also smells very rich at idle. Any help and advice would be greatly appreciated.

Thanks, Bob

cutlassefi

That "rich" smell you have at idle could actually be lean. What color are the plugs?
I'd check air/fuels first. If you didn't rejet the carb after all the mods that's probably contributing to your problem. Next check the amount of vacuum advance and total advance. Let us know what you find.

SBORule

That "rich" smell is more than likely an improperly set float level.

Q-Jets are sensitive to float level and needle and seat sizes when using high volume and pressure fuel pumps. If you have more than 6psi of fuel pressure @ the carb you'll get that rich smell because your needle can't handle the extra pressure and is allowing fuel to leak down the carb and it can do this without the gas over flowing the carb airhorn gasket. You probably smell that rich smell after you turn off the engine for awhile too, right?

A improper float level will cause your valves to ping at part throttle but @ WOT is rare.

Just turn your distributor counter clock wise until the part throttle stops pinging.

I doubt your carb is running lean, if it was you would notice hesitation and even a backfire through the exhaust if it was really lean.

Check the spark plugs is a good idea, black means it's too rich.

cutlassefi

And just a word of note, if it's too lean you'll have incomplete combustion, consequently a smell of raw fuel.

SBORule

It could also be the power valve is stuck in the up position although mine use to get stuck in the down position.

Remove the little screw that holds the secondary meter rod hanger and lift the on hanger to remove the secondary rods, set to the side and make sure it in a place it won't have anything set on it.

Remove all the screws on the air horn and lift up on it very slowly as not to bend any of the down tubes. As soon as the tubes clear the center section of the carb you have to tilt the airhorn toward the throttle linkage to remove it from the carb.

Oh I forgot about removing the choke rod, hmmmmm refer to a Q-jet book on how to do this as I just throw them in the trash.

After airhorn has been removed, push down on the primary metering rods, if they don't move, you found your problem. If they move up and down freely, that's not the problem. Push down on the primary metering rods and let them spring back up a few times until the little plastic retaining thingy pops up & out of the power valves bore, makes it easier to remove airhorn gasket. Remove the float assembly and push down on the arms to adjust the float down so it will close the needle in the seat with a lower fuel level of gas. Put everything back together in reverse of disassembly and maybe that rich smell will go away.

If you are running a high pressure fuel pump, it might just need a fuel regulator to solve your problems.

Lets us know how things workout for ya and if you need some help or run into more problems, post and I'm sure someone would be willing to help ya.

Don't let that little Q-Jet scare ya, they are really easy carbs to work on.

69442

Thanks for all the input. I changed my thermostat from a 195 to a 160 and set the total timing @ 35 degrees. This has cured the pinging problem. It is still running a little lean, so I just ordered some rods & primary jets for the Q-jet.