New motor (350 HO Deluxe) equipped with the Holley 600. Symptoms: Gas mileage has decreased significantly, gassy smell at idle, some smoke at start up, black spit on my garage floor via the tailpipes. The idle is a bit bumpy until the car is warm. The car runs strong.

JamesC

 

sounds like she is running a bit too rich...common holley problem..I'd say a reajustment is in need also maybe alittle timing advance is in order

 

Find out what the stock jetting and power valve is and start there. Go to mortec.com and look for your carb list # and you will find what your looking for. A 6.5 power valve will work fine to start with.

 

First thing to do is probably to try leaning out the idle. The idle mixture adjusters are one each side, in the 1/2" wide block towards the front of the car. screw in for leaner. if you can screw them all the way in then your power valve is bust.

After that it is on to adjusting the jetting, replace the power valve and gaskets while you're in there. Always jump 2 or more jet sizes at a time or you may not notice a difference.

Si.

 

Maybe something as simple as the choke (electric)?

JamesC

 

Could certainly cause you some issues if it stays on long after start-up. I think an electric choke should move to fully open after less than 1 minute. easy one to check.

Si.

 

Choke, float level, ignition. Get those right first. Then start down the rest of the list.

 

Advice code one alpha: If you tweak on the idle adjustments, shut down afterwards and count the number of half turns out from seated they are. Then make sure both of them are equal numbers. DO NOT turn them in so hard they mangle inside. They're made of soft metal, and tightening them much at all will ruin them.

Two alpha: Make sure that at full warm up the choke plate is completely vertical. If not, set it that way, and go over the other adjustments for the choke from scratch - but leave the choke plate wide open adjustment where it is.

Three alpha: First priority is to get the float setting on target. Everything else will be out to lunch if the bowl level is off. 99% of Holley problems dissappear once this is done, because most people don't do anything radical to them.

Four alpha: If you can get your hands on a "TECH BOOK" for Holley carbs - it's worth it's weight in gold (not to mention unburnt hydrocarbons)

I will also mention this, for what it may be worth:
My father was very old school, and never thought he would ever see a spark plug set at anything but .032 I guess...

He changed plugs in a 1975 Eldorado with a high-E ignition and OH MY ***...

Before it was over, the back bumper was blackened for 18 inches in both directions from the tailpipe.

The gap was supposed to be .060 if I remember right.

Make sure of that, plugs are a basic but sometimes the basics get by for whatever reason.