1983 Chevy G30 Van Air Cleaner Search

I have a '83 G30 van that is a Motorhome conversion. It’s a 350ci and the last owner has replaced the air cleaner with a K&N air cleaner. I’ve recently had it in the shop and the Mechanic got it to run good around town. The only problem is that when I made a trip north up I-5 from S. Oregon when I started to climb the Mt. passes the engine would start to miss, running rough and losing power. The temperature was hot, around 100˚ and the engine temperature was hovering around 210˚. I talked to my mechanic about the problem and he is of the mind that I need to get back to the original or stock air cleaner. He says that the original air cleaner had a snorkel that funneled cool air from outside the vehicle back to the air filter/carburetor. I went to my local Chevy dealer and they showed me the schematics for 1983 G30 vans and it doesn’t show the snorkel type system that my mechanic described. I have been to several wrecking yards and recently found a snorkel that I think I can adapt to my '83 van but I’m sure it’s off a later year, possibly a 1987. I did look at the 1987 schematic and it does show the snorkel type air cleaner system. Interesting that on my van there is an opening in the frame above the radiator that looks like it was intended for the snorkel attachment, although it is slightly smaller than the snorkel I pulled from the '87 at the wrecking yard. The wrecking yard owner said that there were some vans that were manufactured for the California market that had a different type of air cleaner. He said that there would be sticker under my hood that would indicate if the vehicle was set up for California emissions. I checked and any stickers that were attached under the hood are no longer there.

Here are my questions:

  1. Does it make sense to return to the original / stock air filter system?

  2. How do I determine if my vehicle is one of the California emissions type?

  3. Are there any problems adapting the snorkel air cleaner system, that I recovered from the later model 1987 Chevy van, to my '83 van?

There are a couple of other items I wanted to mention that may pertain to the situation.

Last summer I had the Van tuned up and they replaced Spark plugs, spark plug wires, distributor cap and rotor. After the tune-up van ran good but then I started to have problems. The van would cut out and miss terribly when you stepped on the gas, no matter what the outside temperature was. I talked to the mechanic and he said that I needed a carburetor rebuild. At this point I started asking around and found my present mechanic who worked on the van and indicated that he did a lot of work on the vacuum system. He also checked the fuel filter and determined that there is no fuel filter other than the one at the tank and then a small stone filter at the carburetor. He has recently suggest cutting the fuel line and installing a in line filter. I haven’t had that done but I may in the future. Now the van runs really good and I can drive it around town and up into the hills and it runs strong. Stomp on the gas and it responds in a solid way. It seems that my problems don’t come to the surface until I try to go on a trip in very hot weather and it includes long steep grades. When I told my present mechanic what was happening he says that the gas is boiling in the carburetor and causing the van to lose power. I told him that when I stepped on the gas and the van shifted into a lower gear the engine runs strong. His response: The fuel is going through the carburetor quickly and doesn’t have a chance to boil so the engine runs strong until it shifts back into the higher gear. He seems convinced that going back to the stock air filter system with snorkel drawing cooler air from outside will help my solve my problems.

The information about the fuel pump is interesting, but I’m wondering if the fuel pump were malfunctioning wouldn’t I have the same conditions I’m experiencing in high gear when the vehicle shifts to a lower gear and the secondaries kick in? At that point the van runs strong and there is no indication of lack of fuel.

The last paragraph on my last reply is in response to a comment that was made to me on another forum in that someone with similar problems had found a solution by replacing the fuel pump.

I doubt that the air cleaner is the cause of the problem. While there are a number of things that it could be and I can only guess due to limited diagnostic info, etc I might take a stab at vapor lock which the mechanic alluded to with the boiling gas comment.

Vapor lock is a common problem with carbureted vehicles and back in the 80s this was common even on brand new cars.

There are some things that can be done to help alleviate this but there are no guarantees.
One is to eliminate the steel fuel line between the pump and carburetor. Add an inline filter and high quality rubber hose.
The addition of a fiber spacer block at least 1/4" thick between the carburetor and intake manifold can help also as it insulates the carburetor float bowl somewhat from engine heat.

Just a story about boiling gas. Back in the 70s/80s many Japanese branded cars used carburetors that had round sight glasses in the carburetor float bowls. On a hot day with the engine fully warmed up one could shut the car off, wait a few minutes, and eyeball the sight glass. The gasoline could be seen boiling away just like a coffee pot.
This in turn caused gas to flood over into the engine and cause a no-start, hard start, or balky running condition.

Unleaded gas seems to be more prone to vapor lock than leaded but since leaded has long been illegal on passenger vehicles, and harmful to the converter, the use of leaded is not advised even if it were legal to use and you could get it at the corner gas station.

It’s also possible (assuming this has the Quadrajet carburetor) that the secondaries may not be opening due to a slight choke problem. An issue with the choke can cause a lockout pin to keep the secondaries closed. Hope some of that helps.

83 is a little newer than my old memory, but when going into the mountains at high altitude we used to advance the timing to avoid such issues.

The local dealer can tell you if your engine was a “California” engine from the VIN. No charge.

It couldn’t hurt to replace that K&N garbage. I would.

As regards the vapor lock (ah, sweet memories), OK4450 has provided a great post. The spacer block was a particularly common adaptation for engines that were subjected to large loads.

Thanks for the comments. This is really good information. I think I will follow ok4450’s advice and make the modifications he suggested. Hopefully I’ll be able to post an update in a week or so.

Vapor lock can be reduced by insulating the fuel line from the tank to the carb (especially where near the exhaust system) using this:


Thanks for the tip. Good to know this is available at the local home depot.

I agree on everything so far. This heat shield is needed if not already installed


and the fuel line from the pump to the carburetor can be wrapped with aluminum foil to insulate it.

Also, ignition timing must be advanced at high altirudes.

The fuel filter in the carburetor is adequate but difficult to service on that vehicle and I have often installed an in line filter in the 3/8" rubber hose at the fuel pump from the tank.

I agree with the heat in the carb/fuel comments. I also doubt that getting a snorkel would solve the problem.

Thanks for comments and information regarding heat shield. I wasn’t aware that part was available.

No snorkle(but they actually had very little effect on power-some engines would actually lose some power when the lid was inverted)dont use a K&N,put an electric auxilary fan on it,will help more then anything else and maybe drop back to a 180 degree.thermostat,that van is working that engine pretty hard(stuff boils quicker at higher altitudes also)

Another issue with excess heat causing carburetor problems is the manifold crossover can get too hot if there is more resistance on the exhaust on one side. Uneven resistance will force exhaust under the intake under hard acceleration and the hot intake will reduce power and cause detonation. The intake can get so hot that it glows red on the side with the restriction after an extended period of wide open throttle. There is a butterfly in one of the manifolds which can become rusty and seize at any position from fully open to fully closed and should be checked.

When you say K&N air cleaner, did they just replace the filter element itself with a K&N, or did they replace the whole intake and they’ve got a cone filter on the end of it?

I agree with others, btw - I’d be looking at vapor lock and ignition timing before I worried about a cold air intake. Generally funneling cold air to the intake only matters when you’re taking off from a stoplight where you’ve been sitting long enough for heat to build up under the hood. When you’re underway, airflow into the engine compartment is generally sufficient that air doesn’t stick around long enough to heat up too much.

Altitude may cause the engine to run bad. The first thing I would do without thinking first would be to change the ignition coil. Don’t buy it at NAPA. While the coil is out, you can look at the center electrode that goes into the distributor cap, there should be a spring with it.

Always check for the #5 and #7 ignition wires being on the wrong plug. The engine usually runs fine except when you need power.

Low speed stalling can happen on your engine when it is partially warmed up. It’s caused by cold air. There should be a choke stove on the exhaust manifold with a nice round hole that fits a pipe that goes to the air cleaner assembly. That pipe is often missing on the stock system because mechanics forget to put it back in. Not all 350 engines will stall but the ones that do stall, really stall.