How to Make a Dual Snorkel Air Cleaner

One of the more sought after parts for carbed V8 3rd gens is the 305 H.O. dual snorkel air cleaner. I wanted one and looked around local junkyards but never found any. I called GM and they wanted almost $300 for a new one, and there was no way i would pay that much for one. So i decided i’d try and make my own. Here is how i made mine.

  • The first thing i did was i went down to the junkyard and picked up 2 complete stock air cleaners. Make sure you leave the one that you have on your car now alone, just in case something goes wrong, you will still have one that works.
  • The first thing i did, was to take one of the cleaners and cut off the snorkel thermac valve. Leave the thermac setup on the drivers side of one of the cleaners. You will need it so you can still attach the factory plastic elbow that goes up to the front of the engine bay.
  • Then, using a dremel tool (a hacksaw will work as well), cut the snorkel off the cleaner.
  • When you cut it off, cut from the top lip of the cleaner all the way to the bottom on both sides of the snorkel. It is important to leave roughly 1" of material around where the snorkel attaches to the air box. This extra 1" is needed so you can eventually drill 4 holes into it for the rivets that will hold the second snorkel to the air box.
  • Once you have the snorkel cut off, put the extra air cleaner on the carb.
  • Take the cut off snorkel and place it up to the cleaner and line out a spot where the second snorkel will go. Make sure that the second snorkel doesn’t interfere with any fuel lines, carb linkage or heater hoses.
  • Once you have a spot picked out for the snorkel to go, mark that area off, and then clamp the second snorkel to the air cleaner.
  • Take the cleaner off the carb.
  • Take some spray paint and spray it down the clamped on second snorkel. This will paint a spot on the air box. The area that has paint on it will have to be removed so that air can flow into the air cleaner. I used a cut off disc on the dremel, to cut out the area for the hole.
  • Once the hole is cut, re-clamp the snorkel back on the air cleaner lined up with the lines you made before.
  • Now that there is a hole in the cleaner, you should be able to see the hole of the snorkel. You will proballay have to go back and remove some material from the cleaner box so that the hole on the snorkel and the hole in the cleaner box is the same size.
  • Now that you have the holes cut, it is time to attach the snorkel to the cleaner box. Depending on what you want to do, you can either use rivets or spot weld the snorkel to the cleaner. I drilled 4 holes in the extra metal around the snorkel and put rivets in them.
  • Once the snorkel is on, you MUST make sure to clean the cleaner out! The box will be filled with metal shavings and it won’t take all that many to cause a significant amount of damage to your motor.

Tips to help out

If emmissions aren’t a concern, try and find a late 70s air cleaner off of a GM car that uses a QJet. They have an inlet that is alot larger than the stock inlet. Also, the stock 305 H.O. use these larger inlets. GM sells plastic elbows that will attach to these inlets, but will still use the stock air scoop on the drivers side. You can also buy an air scoop for the passengers side

If you don’t want to buy the elbow from GM, you could get a 4" metal ducting hose (the kind used on the back of dryers) at Home Depot. You could clamp this to the snorkel and duct it up to the front of the car. I did this on my car and attached it in behind the passenger side high beam light. I removed the light and made a home made ram-air system.

The Bottom Line

So, after all this work, i bet you are thinking "Well, how good is this this thing and is it worth it?". I can’t say how well it will work in your car but, I managed nearly a full .5 second decrease in ET!.

If you have any questions about this how to article, please send me an email at [email protected] and i will try to answer any questions that you have