Since buying my 1966 L79, 4- speed, AC, PS, PB Coupe on November 1st, I have posted numerous questions and I have really appreciated the knowledge on this site. Everyone always says, keep us informed with updates, so that is what I am doing. I hope you can see progress being made.

My first post was about 2000 date code tires, and the tires and wheels have both been replaced for safety. My next post was about the issues with the lack of PVC on my engine. I got many great suggestions and I have made good progress. The attached picture shows the new routing of the PVC, as much as I can do right now, and new routing for the PB booster vacuum, as well as moving the coil to the correct location. I still have to re-clock the distributor to put in the new tachometer cable. I can't complete the PVC system as I cannot find a 66 L79 crankcase vent tube. This was removed by some previous owner along with the PVC system. They capped the vent tube hole in the block and I still don't know if they removed the "tomato can" inside the engine. I tried, as some suggested, to run an endoscopic camera down the front oil fill tube to see if the "tomato can" was still there, but after a couple hours of trying, I googled and looked, and there is really no way to get into the valley from the oil fill tube. The only way to check, without removing the intake manifold, is for me to remove the core plug where the crankcase vent tube is supposed to be. I will do that. However, to complete the PVC system, I need a crankcase vent tube. I have spend hours on the computer and phone, calling all over, looking for one, but everyone is out of stock and waiting for evidently one reproduction manufacturer to make them. I need one. If anyone has one, please contact me. As an option, one of the members here said they had a tomato can and an earlier model of a vent tube assembly, one that bolts in the same was as the correct 350/365 tube, but just has a short tube coming off the mounting. It wouldn't be "correct" for my car, but would this vent tube work with the rest of my L79 PVC system if I ran a hose, and sized it to fit, to run from this smaller, shorter vent tube to the air intake on the carburetor air cleaner? Would it work to complete my PVC system, at least until I can find a correct 350/365 vent tube?

I have also just received my restored dash cluster back, and can now re-install. While waiting for the dash cluster, I took the time to add 5 inches to all the wiring harness connections to allow my old, fat fingers and hands behind the dash to reconnect everything. I have also had my steering box blueprinted and unsafe rag joint replaced. I have added seat belts, and the back-up light switch to the transmission that was removed, and I still have more to do. I hope to have most things done to get the car back on the road, reliable and safe, as soon as possible.

I will post more questions I am sure, and I appreciate all the knowledge on this forum from those who love our America's Sports Car.

 

The earlier 365 vent tube should fit your 66 L79 intake.
Apart from part numbers and other minor details, I’m pretty sure the intakes are same shape.
Whether you can make it fit the air cleaner base is another question, but if it’s similar, just shorter, then a longer rubber tube should fix that.
https://www.rpidesigns.com/1964-1967...ube-350-365-hp
This looks right to me, is it in stock though ?

 

Thanks anyChevy. That is the part I am trying to find, but no one has it right now, I actually called RPI today and they don't have it either. Volunteer Vette said they got their last shipment in 2024.

This is the part I was wondering if I could make work, by joining a couple different sized rubber hoses.

 

Camaro right ?
That’ll work in the meantime.
You really need to ventilate the rear of the crankcase, just a PCV is not enough, especially if you have some blow by.

I got away with just a breather cap on the oil fill tube on a 68 L79 (no vent tube hole in block) with no problems, but I don’t recommend it.

 

AnyChevy is correct for the fresh air tube from the air cleaner to the opening at the rear of the block on a 66. However, the L-79 with aluminum intake requires a different tube as the air cleaner sets a bit higher. I did use the 300 hp fresh air tube with an L-79 intake, but made a rubber gasket to seal the tilt of the fitting of the tube to the block. A short piece of 1" rubber hose connects to the air cleaner. I assume you have the correct air cleaner base with the tube connection???
1st, have you tried removing the freeze plug at the back of the block and using a piece of flexible rubber, vinyl, etc, hose to push into the opening to see how far it will go? The 'tomato can' will not allow more than 6" or less into the valve galley. The freeze plugs are cheap and easily installed, but you would probably need to remove the distributor.
If no tomato can, you will have to pull the intake to install one.
Now, the key here is "fresh air" intake. The air cleaner filters the air to keep trash out of the engine. If the PCV valve is working properly there is no oil vapors coming out of the back of the block, but oil could splash out due the valve train movement, thus the tomato can. On later Chevy engines, 68 up, GM used a vented cap in the valve cover, passenger's side, for fresh air intake. The PCV valve was in the driver's side valve cover, not the fill tube. You could use later valve covers to add the fresh air intake.
Attached is an article from one of the smartest members of the forum. This will help you more than I can.
Ron

 

Could you send us a picture of the carburetor and air cleaner you currently have? Include the underside please.
Aloha,
Rene'

 

There are crank case tubes available in the Bay......
Aloha,
Rene'

 

Here is an original PCV fresh air intake on R66 with the original air cleaner and carburetor. For your reference. If you are talking to the OP, he can add his so we can further help him.

Air cleaner base with fresh air tube and 1" rubber hose..

Fresh air tube to engine block

Original 3367 Holley with air cleaner base and fresh air tube shot.
Please excuse the mess, I am chasing oil leaks.
Hope this helps
Ron

 

Thanks R66. The next time I go out into the garage with some time, I will pound out the core plug on the back of the block and stick my endoscopic camera in there to see if the tomato can is still in there. If it is, I will just put in the short vent tube in and run from there to the tube connection on the base of the air cleaner with hose, sizing it up correctly. I will use the short vent tube until I can find a correct 350/365hp one. I have had one backordered since November. Rene-Paul, I have been watching regularly, but the vent tubes posted on Ebay are either for the 300 hp engines or FI engines, which are not the same as the L79.

 

I think it might work with the fitting you posted in #3 might work, but you will have reduced fresh air flow which may choke the system down a bit. It is worth a shot. I have an idea for a baffle you could put in the fitting if the tomato can is missing, but would have to find the material. I'll think about it after I get R66 back together.
Ron

 

Give David Sokolowski in California a call...I bet he has dozens of these crankcase vent tubes in his stash...(310)-329-5334

 

A 75 Chrysler 440 cu in used this canister full of course aluminum wool and a baffle, but I don't know that you can fit it in under the distributor. I would still rather see you go original GM.

5/8" hose fitting. has internal baffle. A grommet would be needed to fit in the hole a the back of the block.
If the engine is not worn with a lot of oil vapors in the crankcase and the PCV valve is working properly, there should not be a lot of vapors in the engine. Also, it is a fresh air intake, it is under vacuum with the engine running, so as long as the oil doesn't splash up into the tube and then into the air filter, there is little need for the tomato can. But, one never knows without trying it.

 

Chief,
All of the above posters have solid advice. I have a similar problem on my '65 L79. The fresh air tube on my car is missing and I have had one on back order for quite some time. Believe it or not, someone replaced that fresh air intake tube with a C1 road draft tube sometime in the distant past.
Read the Hinckley paper, it contains a very good explanation of the evolution and purpose of the PCV system.
I think Dave S may be your best bet for a used intake tube. I'll have to call him also. I might also suggest eBay or some of the advertisers in the Corvette Restorer.
Good luck and keep us posted on your progress.
John

 

Thanks for the great suggestions. Interesting idea from Dodge! I wonder if I could put a screened or aluminum wool "baffle" or "Filter" in line from the vent tube up to the air filter temporarily if my tomato can isn't in place. Would think that would be better than nothing until I can get time to pull the intake if the tomato can was removed by a previous owner.

I will call David this morning. I would rather have the correct piece, but I am going to try to have something in place by the time I fire the car up after I put the restored dash cluster back in next week. (don't want oil all over the interior before I hook up the oil pressure gauge) I have been watching Ebay, have called probably 15 Corvette parts places, and have the repo piece on back-order at two vendors. Hopefully I will come up with something.

 

For a temporary non original fix, put 2 or 3 inches of stainless steel pot scrubber material inside the 1" hose to the air cleaner. Don't pack it too tight as the air will need to flow through it. Put straight pins or small pins of some kind above and below the scrubber material thru the hose to hold the pot scrubber material in place. Then adapt the 1" hose to your fitting in the back of the block. This will be similar to the Chrysler filter material in the cap I posted above.
The fresh air inlet from the air filter is normally under vacuum from the PCV valve and thus has no oil coming into the hose except from 0 vacuum at wide open throttle and hot shut down of the engine. The oil, if any, should be filtered out by the SS pot scrubber material. I don't think you will need any additional baffles, but just a guess. Then again, with a fresh engine, you should have very little oil vapors as you have little blowby.
Ron
PS: I am not responsible if your wife catches you in her kitchen and sewing cabinet. It could be fatal.

 

Update! Thanks everyone, and Thanks Leif! I called David Sokolowski the other day, and he called me back today. He has an original 350/365 hp crankcase vent tube that he is willing to sell me at a very fair price. I will be sending him a check and hopefully will be able to return my L79 to the correct PVC system with original/repo parts to allow it to operate as intended, very soon! I also have the short crankcase vent tube as I described in post #3 coming that I won't be using, but whatever, I am just so happy to find the correct parts with the help of those on this forum. I am making progress to correcting a number of issues on this car and I am really looking forward to getting it on the road soon to enjoy driving it!

 

Good to hear You’ll need long the bolt, the gasket and the fibre washer as well

 

Didn't even know these cars had a polyvinyl chloride system. Sounds really advanced, for the time.

(I say it backwards all of the time. And I get endless crap from my car buddies for it.... )

 

Another update on this topic. While waiting for the correct 350 hp crankcase vent tube, and after installing new speedometer and tachometer cables, I took some time this afternoon to knock out the core plug that a previous owner installed on the rear of my engine block, evidently when they removed the original PVC system. I did not have to remove my distributor to do this. After knocking out the core plug, I ran my endoscopic camera down the hole and INTO THE INSIDE THE TOMATO CAN! Obviously, when they removed the PVC system, they didn't go into the engine and remove the tomato can! So now, once the crankcase vent tube arrives, I can complete the restoration of the PVC system. Relief. One more thing to check off the list!

 

Nice to have some good luck and a bore scope .