Holley #3310 Problem

[toobroketoretire]

Yesterday afternoon I removed my #3310 Holley so I could cut the front bowl vent "pyramid" off the choke horn to provide a little more clearance to my very low air cleaner lid. To prevent any debris from getting down into the venturi I taped the choke butterfly closed and proceeded to remove the pyramid using a hack saw and file. It came out real nice BUT this morning when I drove it to my mailbox on the highway it would only idle at 300 rpm in DRIVE, it idled real rough, and it was smoking a little bit so something was obviously wrong. When I got back home I looked it over REAL good and found the problem(s). The right side idle bleed had a tiny piece of debris stuck in it's hole and one of the secondary bleeds had what appeared to be a grain of sand stuck in it's hole. I used a can of spray carburetor cleaner to blow the debris out and now all is back to normal again.

The point is it doesn't take much of an obstruction in the bleeds to make it run awful so if you ever have a sudden idling problem check the teensy-tiny bleed holes first.

Here's a picture of an early #3310 without the pyramid and a later #3310 with the pyramid. And a picture of my #3310 with the pyramid removed.

 

[toobroketoretire]

Air Bleeds MUST Be Open

As the idle air bleeds have such teensy-tiny holes the bleeds are usually overlooked when an engine is having an idling problem. Those bleeds are there to allow some air to mix with the fuel to provide a "foamy" fuel mixture for easier combustion and they play a very important role in how well an engine runs. So when troubleshooting an idling problem don't forget to check out your air bleeds.

 

[toobroketoretire]

I found the stock #72 main jets would produce a .9 O2 sensor voltage at 60 mph whereas #70 jets give me a near perfect .7 volts. One of these days I'll test it at a full throttle and see what my O2 sensor says. But as I very rarely give it a full throttle it's not an issue that needs to be addressed any time soon. Bit it would be nice to know.

 

[kpic]

Simply said for OBD2 .9 is rich and .1 is lean.

FYI: You have OBD1.




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[Hib Halverson]

I found the stock #72 main jets would produce a .9 O2 sensor voltage at 60 mph whereas #70 jets give me a near perfect .7 volts. One of these days I'll test it at a full throttle and see what my O2 sensor says. But as I very rarely give it a full throttle it's not an issue that needs to be addressed any time soon. Bit it would be nice to know.

DO NOT attempt to calibrate WOT air fuel ratio with a narrow band oxygen sensor.

Even trying to set part throttle jetting with a narrow band is difficult because the only situation where a narrow band has enough resolution to provide useful data is when the mixture is right at 1.00-lambda or 14.6:1 AFR for real gasoline or 14.2:1 for E10 blended gasoline. Either side of stoich and the sensor's resolution is so poor, you can't gain useful data.

 

[toobroketoretire]

As my secondaries only get opened maybe twice a year at the most I'm not going to lose any sleep worrying about the air/fuel ratio. The whole point of this thread was to remind you about how necessary it is to keep debris out of the tiny air bleed holes because a teensy-tiny speck of debris is all it takes to louse up the idle quality. Had I been Joe Average and taken my '71 to a shop they probably would have recommended a new carburetor. In a way I feel real sorry for people who don't know anything about their cars and HAVE to take them to a shop for any maintenance or repairs and pay $100 per hour for a pimple-faced kid to work on them.