Hi guys. I have a Holley Carb (not sure which model) but its a double pumper if im not mistaken. I only have basic experience with carbs, I was more into injection before.

Anyways, my car runs crazy rich. There is way too much gas running through and the milage is a nightmare. So I started looking up some info of how to adjust the mixture and maybe the floaters and I saw something regarding to the adjustment screws:



On the first image (pink) you see the left side of the carb (looking at it from the front of the car). It have one screw in the left and right side in the front (pink, picture 1 and 2) but no screws in the rear of the carb (green, pic 2 and 3. Aren't there supposed to be the same screws or its normal that there are none?

Can somebody take a look at the and give me some info about how to adjust it to see if the screws make any difference. They are both only half way turned from fully turned in (should be lean according to what I was reading). I was reading somewhere to turn them back more than one full turn.

Also the car turns off sometimes going over bumps. Could that be a sign that the floater have to be adjusted too?

Thank you very much.

 

Looking at your first picture you posted, you have some sort of vacuum secondary carburetor. If it says 3310 -something on the back side of the choke horn (the tall part in the middleish where the choke functions) it's a 750 vacuum secondary.

There are a lot of people who hate Holley's because they're "hard to get adjusted" but that's just because you need to learn all the ins and outs to get it running right. There are a lot more adjustments than other types of carburetors and especially it'll be difficult at first if you're used to fuel injection. I'd recommend finding a book, manual, or video online about basic holley tuning. There are various ways that you can adjust the Holleys for street use.

You can adjust:
-jets, primary and secondary (because you have a secondary metering block in your carb)
-float level in primary and secondary
-idle mixure screws for driver and passenger side (the small screws in both sides of the front of your carb)
-accelerator pump squirter size
and later on the vacuum secondary spring

I'm not trying to overwhelm you with all these things, just helping you be aware of all the adjustment for running great. What I would start with first is to take the primary and secondary float bowls off and see what jets you have in it. If it is really rich that would be an easy place to start. Start doing a little Holley research too to see what you're dealing with.

Goodluck! It always takes a little time in the beginning but once you get them tuned up you'll never go to anything else. The ease of tuning and throttle response is unmatched in my opinion. Hope this helps!

 

What I did right now was adjusting the idle mixure screws to 1 1/2 turns. It was at 1/2 turn. I heard immediately that the engine sounded much more aggressive when I turned it on. I had to adjust the idle rpm a little higher though. Next thing I would like to check are the floaters. Are there any tutorials how to do it correctly?

 

Lots of videos. It only takes a minute to look.
Here's one....,

Also check your jet sizes.

 

Thats exactly the one I was using. I am in the process right now. Both floaters were way too high. The gas poured out in both sides when I opened the screws. Im adjusting right now.

 

Its a combination, your going to want to make sure your timing advance is right, then once that is right you can set your idle, shoot for 850 in park, 650 in gear, go buy a vacuum guage, they are usually about 20$ hook the vacuum guage to a full manifold source, there will be one at the base of your Carb at the very front. Set your screws 1.5 turns out each side. With car warmed up set your idle so its around 850 in park, 650 in hear. Now apply your park brake, and chalk your tires. Now put the car in drive and watch your vacuum guage, your going to start turning one at a time, and pay attention to how far you turn so you can make sure they are balanced. Your aimimg for your highest vacuum reading on the guage. This will clean up the idle and now be set right, small movements make big changes, so do it in small increments and watch the guage for a few seconds each time to see how it reacts. Too far in and it will drop, same for too far out, so you will see what I mean when your doing it. Once that's done you will see a big difference in idle quality. The "mean idle" you were describing sounds cool, but generally means your settings are out to lunch. Once its right the idle may be tamer but it will have crisp throttle response and not make your eyes water lol. This should get you started with the basics.

 

I actually have a gauge installed on the pipe. I just finished dealing with the floaters today. I damaged one of the gaskets and it got dark by the time I found one in a store but now its sealed again and the floaters should be on a good level. Tomorrow I will check everything again and test drive it. I really really hope it takes less gas now but with both floaters being flooded before, it can only be better now.

This is the car btw. Im building it up. Its a great base, only have some rust at the T-Top, the rest is literally rust free. Not bad for a 84'.

 

Real pretty car man.....
Float....say it with me......Float.....lol.
Just messin with ya.....good luck on the test drive.

 

Yep....floats. Now that they are adjusted, how does it run?

 

I dont know I didnt turn it on yet. I want to do it tomorrow. Gotta go south of the island anyways. I cant turn that car on so late. I will wake up the whole town. Its loud as hell haha.

 

Well it runs way better, smoother but I still see the tank needle going down by the minute...

 

Lol, welcome to the muscle car world....

 

And again...check to see what size jets you're running. It's been a long time since I've had a Holley apart but IIRC they should be in the plate between the float bowl and the carb. But hey! running better/smoother is a good thing right? Good luck!

 

I think I have to get a 316, 325 or a Civic Vtec after all for daily use

 

Read the Holley tuning sticky on top of the Carb forum. Follow each step.

 

What is the list number on the air horn? It looks like an older 3310 (secondary metering block) If so, it's a 750 cfm carb and is calibrated to be too rich on a 305-350 with a mild cam, small exhaust, etc. That being said, it can be made to work a little better, but won't be ideal. You can put a stiffer spring on the secondary side to help out a little.

 

Hard to be 100% sure from your photos, but it looks like every vacuum port on the carb is plugged. That means you can't be running vaccum advance on the distributor which means you will NEVER get good MPG. If it is a mild 350 with overdrive, you should easily get 15 MPG. Anything less and something is probably wrong.

 

Looks like his first pic has a vacuum line to the timed spark port on the primary block.