I just rebuilt my Holley after a local shop told me the carb wouldn't adjust properly. It went from rich to lean. No in between. They said it could be an internal problem or just the wrong size jets. I was told by the local speed shop that the 3310 has 72 for both primary and secondary jets. When I rebuilt it I saw 68 and 76. I can't remember off the top of my head which side had which jets. The same speed shop said that those jets were ok given the mods on my 390. They also looked at the metering blocks for defects but found nothing wrong. I replaced the needles and other internal parts including the power valve. I had two choices for power valves. 35 and 65 Hg (?) I used the 65. I didn't do anything with the secondary controls seeing how the kit I was sold didn't have any parts for the secondary controls. Here is my problem: The carb won't adjust still. It goes from dangerous lean to flame throwing rich almost instantly. I've tried messing with the floats alittle. Didn't see how that would help but I was willing to try anything at this point. I was told to take the motor up to about 4K RPM then shut it off. No idling. Pull the plugs and check for rich or lean condition. That was supposed to tell me if the jets were too big on the secondary side ( which leads me to believe the 76 jets were on the secondary side). Any truth to this? I know when it's rich cause I can smell the raw gas comming out the exhaust when I back off the gas. I have an all MSD ignition system (pro-billet Dizzy, blaster 2, 6AL, 8.5 mm wires and accel header plugs gapped to .45 (or is it .045?) The entire motor has lees then 200 miles on it. Please help!

 

The gap is .045.
Are you talking about the idle mixture? How much engine vacuum do you have at an idle? Large camshaft? The larger jets should be on the secondaries. I am guessing that you have an old 3310-1 since it has a metering block in the rear instead of a metering plate like the -2 and newer. I also wonder how far open are the secondaries at an idle. If they are too far open or closed, it could make it hard to adjust.

 

Idle is alittle rich but not as bad as when I try to get on the gas. As far as the secondaries being open how do check or fix the opening of them? Also I called them metering blocks cause thats what I heard them called. How do I tell if it is a metering plate or metering block? All I know at this point is the primary and seconadry look the same except for the pump not being there on the secondary. The camshaft is a stock one. I would have to pull the paperwork out to find out what the specs are. It was a checker style short block.

 

The secondary throttle plate opening adjustment is a little screw that looks like a grub screw. As I remember, it is accessible from underneath when the carb is off the manifold. It is not adjusted while the engine is running.

The float settings is where you start. You should have good, precise float settings before you begin any other tuning. I assume that you know to pull the sight plug and then simply use a 5/8 wrench and screwdriver to adjust for a fuel level that is exactly at the bottom of the sight plug opening.

Your choice for a 65 power valve should be pretty close, you certainly wouldn't want to use the 35.

The metering block is about 3/8 or 1/2 inch thick between the fuel bowl and the main body. If it has a metering plate, you will not see it without removing the fuel bowl.

I'm disappointed in the shop that told you that you should have specific size jets. Every application is different and this is one of your tuning parameters.

There are a number of ills that is possible to experience with a Holley. I have actually seen Holleys with defective metering blocks from the factory. It is likely that they were really not defective, it was just that they did not match the carburetor.

Also, since you say there's lots of raw gas, if you have trouble adjusting float level, remove the carb and turn it upside down and make sure that you cannot blow through the fuel inlet. If you can, that means that a needle and seat is leaking in one end or even both ends of the carb.

Also, since you said it goes rich then lean, make sure that the accelerator pump check ball is in place.

It's very difficult to troubleshoot something like this long distance, but just keep checking things and posting as many details as you can and someone will lead you there, or say something that will ring a bell with you.

Hope this helps,
Doc

 

Float setting was set and rechecked right after rebuild. I have two metering blocks then. Not metering plates. I learned something new today. The shop told me that the 3310 comes with 72 jets from Holley. It was a used carb that I bought from the speed shop in town. The previous owner switched the jets. The check ball is the little BB that always fall on the floor when you forget about them during the tear down correct? If so I didn't see one when I took it apart. Maybe that is the problem? I wil have to tear the carb off the truck on Thursday when I get back to town. I'm about to go buy a 750 Double pumper if I can't get it fixed soon. I had the same problem before the rebuild So I rebuilt it only to find that the problem was still there. At least I know what jets I have now.

 

Ok I was thinking about this for the last three days since I was out of town. I have a minor rich condition when I idle. the problem gets really bad when I step on the gas. If I floor it and hold it I can stall my truck. If I slowly apply the gas I can get it to the floor with only a minor backfire then it takes off. I have 68 primary jets and 76 secondary. I was told the 3310 came with 72 on both sides from Holley. I think I may go to 72 on the secondary and see if it still stalls when I floor it. I believe I may be flooding the motor when I open up the secondaries. The secondary throttle plate opening screw may have something to do with the problem too. My instructions are missing for the Holley. Do I just turn the screw until it is seated then back it off a couple turns? I just got back today and the kids are screeming for attention so the truck will have to wait another day.

 

There isn't a cheater screw in the secondary linkage slot is there? This will make the secondaries open way to fast and cause a bad hesitation.
I would also check the fuel pressure to make sure it is 6.5# or less.

 

Ok The fuel pump is one of the few stock parts still left. I will have to get a pressure guage for the fuel. My youngest son goes in for a root canal and filling tomorrow. The truck is going on the back burner until next Monday. Can a stock fuel pump put out too much pressure? Also what is this cheater screw you speak of? This is my first Holley. I have no clue when it comes to this beast. Please fill me in.

 

It sounds like some good tips. Maybe I can add a few ideas??

The acc. pump check is a bullet shaped steel piece under the pump shooter, if that is missing it will cause fuel to be sucked thru the pump shooter when the engine revs up- it will be rich.
Is it possible the secondary vacuum actuator spring is missing or a very light one?? It might be allowing the secondaries to open way too soon, or if missing they could be opening slightly even at idle.
The secondary stop screw could cause poor idle or improper secondary actuation, but it is easily adjusted. You want to turn the screw so the secondary plates are completely closed and then turn the screw 1/2 to 1 turn after contact with the secondary tang. BTW, it is on the pass. side and much easier to reach when the carb is turned upside down.

 

Putt, are you refering to the pump discharge needle valve? If so I put a new one in it when I rebuilt it. The kit I got for my carb didn't have any parts for the vacuum secondaries. It was a kit for the double pumper but the guy said it would work for my carb since he didn't have one for the 3310. I will try to get the energy to pull the carb apart again this weekend to check the spring. The only parts not touched by the rebuild were the vacuum parts. I guess I know where the problem could be now. I knew I should have waited to get the 3310 rebuild kit. The carb was used and it came off a hot rod Bucket style car. It idles ok. 1050 RPM in park/neutral. 900 RPM in drive/reverse. Is that acceptable? I turned the screw up alittle when I first started the motor so it would idle. I just never turned it back down. I will check the secondary stop screw first since I don't have to replace all the gaskets on the carb to check that. I really have a feeling it's the spring though.

 

Yes that is the pump discharge needle valve.
Your idle speed is a little high. That could be causing some of the rich/lean problems because too much of the tranfer slot is uncovered at idle. That would make it rich, then lean off idle. Where are your idle mixture screws set at?
You can tell if the spring is there by opening the throtle all the way(engine OFF) and pushing up on the secondary linkage, it should return to closed quickly if the spring is present. I have found few kits for the vac sec Holley that have the secondary diaphragm and none have the springs. I would suggest checking what color spring you have. I think you should have either a plain or a purple color spring with your combo.
Rereading, I noticed the 4K shut it off suggestion...it won't give you any info on the secondary mixture because they will not open without the engine being under a load, it would give you an indication of primary mixture however.
List #3310-1 should have 72 jets on the primary and 76 jets on the secondary. List # 3310-2 thru -5 all use a secondary metering plate. They could have switched to a block from the plate in which case the 76 jet is one size too big(not really noticeable) Holley reccomends a #75 jet to replace that metering plate.

 

Putt, I got all excited after reading your post and ran outside to check the spring return action. I got outside and realized I left the truck with the girlfriend at her work and took our car. Stupid me. The 4K RPM thing was while driving. He wanted me to take the truck to 4K (unlawful speed around here) then shut it off while driving. He was insane. I have no power steering as it is. Now he wants me to take it to 4K then shut it off while driving and lose my power brakes too? Doesn't seem smart to me. I have no idea how old the carb is. I bought it used. It has 68 primary and 76 secondary jets. I'm guessing it's the 3310-1. I did some reading on the Holley web site and read that switching to one size (76 to a 75) wasn't needed due to other factors in the motor. Two sizes would be the only way to justify the switch. With the truck in park what should the idle be set at? What RPM should I see in drive/reverse? Just incase it helps, I run an MSD pro-billet and had to switch to the lightest springs just so I could drive it. I still have the carb issues but they aren't as bad as when I first put the carb on. I run 91 just to be on the safe side even though my compression is around 8.5

 

Normally you are looking for 700-750rpm in park and 600-650rpm in drive/reverse. I agree that one jet size is not enough to notice.
Have you double checked your timing, it sounds like it might be off. Perhaps a slipped damper( timing mark out of place)? Does that dizzy have a vacuum advance?(I think it does not)
Try slowing the idle down with the idle speed screw and then adjusting the mixture screws to smoothest idle, it will sometimes take several back and forth adjustments from idle speed to mixture before it is set.

 

Ok I turned my idle down to 850-900 RPM in park and about 700 RPM in drive. I turned the mixture screws both in until they just began to snug then backed them out 1.75 turns each. That is where they are now. My secondaries are closed all the way at idle as best as I can see. I looked at the screw I believe to be the secondary stop screw. I tried to confirm it with the Holley diagram but I'm not sure if I'm looking at the right thing or not. I found a flush style screw that is on the passenger side at the base of the carb. The seconary lever seems to rest on it when they are closed. I currently have about 5 threads showing.

*The secondary stop screw could cause poor idle or improper secondary actuation, but it is easily adjusted. You want to turn the screw so the secondary plates are completely closed and then turn the screw 1/2 to 1 turn after contact with the secondary tang.*


Please bear with me on the following. I like to make sure we are on the same sheet of music. The tang is the lever that sits against that screw when the secondaries are at rest correct? I believe if I back the screw out until the first thread is flush with the carb the secondary tang will rest on the base plate of the carb is that correct? So... Do I back it out until the tang no longer touches the screw then screw it back in about 1/2 to 1 turn?

Also my dizzy does not have vacuum advance. It has mechanical advance and I have the lightest spring that came with the dizzy installed. I didn't do anything with the weights that came with it. Timing may be an issue but I can't get the new dampner until Friday at best. The guy at the shop that tried to do the tune up said he believes my timing marks may be off. He said he couldn't be sure because of the carb problem. At 7 degrees he had a rough motor. Could have been a slipped ring he said or just the carb is really messed up. For 60 odd dollars I'll get the piece of mind from the new one. I just hate doing shotgun trouble shooting.

 

Yes that is the screw, however the throttle plates in the sec bore will hit the venturi before the tang rests on the baseplate. Therefore you need to watch the screw/tang contact and when they just touch, you turn another 1/2 to 3/4 turn for your combo. IMO anyway

You need to be sure the advance is smooth in the dizzy, both on advance and return to base. Does the rotor smoothly turn by hand and return by spring action??

A thought...you said it was rich/lean?? What size acc. pump shooter do you have?? It is stamped on the face between the outlet holes/tubes. It should be a 25 or 28 pump shooter.