[xk49]

I've notice that my engine appears to have no draft tube. Someone on a FB page said I should have one.

I bought the car restored with a period correct engine (327 1964 SS) and was refreshed with cam, headers, double hump heads and carb. Bare with me as I don't have a lot of engine knowledge, but I though all engines of this period had some sort venting for the crankcase?

There's no outlet on the valve covers and other then the oil breather/filler tube at the front there's only one other outlet on the back of the engine where a line goes to the brake booster. The line that goes to the brake booster looks like it attaches to where a draft tube would have been, at least that's where it was on a 57 Chevy that I had a few years back.

Do you need a draft tube? If so, what would I do to remedy the situation?

Edit: There is a draft tube on the back of the engine block going to the intake manifold. Brake booster line comes from the intake manifold. Couldn't see well onto the back of the engine and I got the two confused as they crisscrossed on the side of the engine I didn't have access to(car is in storage against a wall.

 

[Rich-L79]

If your brake booster line is connected to the back of the block you wouldn't have functioning power brakes. I assume it is instead connected to a fitting on the back of the intake manifold.

If the 327 is of the 64/65 vintage there would be a large opening at the back of the block, behind the intake manifold and just before where the bellhousing attaches. I'm going to take a wild guess that if you have the older style block with the large hole at the back of the block that it is capped off.

Is the cap on your oil fill tube a breather or a sealed cap? If it is a breather, that is how your crankcase is being vented. Not ideal but basically functional.

A properly set up 64/65 block would be set up with either a draft tube or a closed PCV system. A draft tube would simply be a large metal tube bolted to the large hole at the back of the block. The tube ran downward along the bellhousing and vented crankcase gasses to the atmosphere. A (better!) system is a closed PCV system which has a line connected to intake manifold vacuum which has a one-way PCV valve inline. This line would be connected to the crankcase via a hose to a valve cover or the oil fill tube. Fresh air is introduced to the crankcase via the large hole at the back of the block which is connected via a pipe to the air cleaner so the ingoing air is filtered. This same arrangement can be accomplished with the same vacuum line and a filtered oil fill cap so that the air is drawn out at the vacuum line and in via the filtered cap.

Quite often when these older style engines are hot rodded an aftermarket air cleaner goes on which has no provision for the clean air PCV pipe so it is eliminated and the hole is plugged. If the PCV system isn't recreated in some fashion, most folks just added a breather cap to the oil fill location, so it functions more or less like a draft tube. But a breather cap can also be messy.

Later engines without the hole in the back of the block ran a PCV vacuum line to the valve cover and used a breather cap.

Pictures of what you actually have right now would be helpful.

 

[DZAUTO]

The VERY LAST year for a road draft tube (on small blocks and Chevelles, there were NO 63-4 Chevelles) was 1962----------------------------EXCEPT for California delivered cars. California delivered cars, in 1962, got a PCV valve system, instead of a road draft tube.
Thus, ALLLLLLLLLLLLLLLL 63-later cars have some kind of PCV setup. The MOST common PCV setup consisted of a fitting on the hole in the rear of the block (ONLY 56-67 blocks had this hole, it was gone on 68-later blocks). There was a hose attached to the fitting and then the other end of the hose was connected to a PCV valve that was connected to a manifold vacuum port at the base of the carburetor. That was the MOST common setup.
There was NEVER, repeat, NEVER a road draft tube installed on ANY Chevelle engine. They ALL had a PCV system.

Here are examples of 2 road draft tubes, last used in 62.

Here are examples of the PCV fitting and long attching bolt that replaced the road draft tube in 1963

ALL 55-67 small blocks had a vapor separator installed at the rear of the lifter valley. In 68, when the rear hole was eliminated, and holes were added to the valve covers for PCV fittings, the vapor separator was no longer needed. The valve covers, with holes for the PCV valve and grommet, had a baffle inside the valve cover for vapor separation.

Here is the hole in the rear of a 56-67 block (next to the distributor hole) for a road draft tube(56-62) or a PCV fitting(63-67). The rear of a 55 block was totally different (55 blocks were ONE YEAR unique).

Here are views of the rear of a 56-67 block, where the boss/hole is located for the road draft tube or PCV titting.

This is the rear of a 68-later style block with no hole.

 

[GLHS60]

The very last Chevy with a road draft tube was the 1967 L-88 Corvette.

Thanks
Randy

http://imgur.com/mZUNMPY

 

[DZAUTO]

The very last Chevy with a road draft tube was the 1967 L-88 Corvette.

Thanks
Randy

http://imgur.com/mZUNMPY

That is exactly correct. But it was ONLY on a Corvette.
I was providing information on small blocks and Chevelles.
I will go back and edit my reply to be more specific.

 

[Bob Tiley]

A photo of your engine compartment would help us see what you have.

 

[AZMARK]

My system has the pvc connected to the oil filler tube and the draft tube fitting attaches to base of air cleaner.

 

[DZAUTO]

My system has the pvc connected to the oil filler tube and the draft tube fitting attaches to base of air cleaner.

That was one type of PCV plumbing systems.

 

[GLHS60]

Sorry, I wasn't criticizing your excellent post!!

I was looking through my pictures for the 55 only block and found the L-88 one.

The 55 block was sure a weird one, now I have to find a picture, I have one somewhere.

Thanks
Randy

That is exactly correct. But it was ONLY on a Corvette.
I was providing information on small blocks and Chevelles.
I will go back and edit my reply to be more specific.

 

[GLHS60]

1955 Chevy 265 V8 block

http://imgur.com/h0tTWv8

 

[GLHS60]

1955 265 V8 block rear view.

http://imgur.com/KMOKHN7

 

[LeoP]

My Dad's 67 Malibu that he bought new and I was the only one to ever do any work to the engine, had a road draft tube. It was a 283, 2bbl, powerglide car!!

 

[Rich-L79]

But back to the original question: The funky 55-only draft tube is not something the OP would be encountering. He has a 327. So while interesting, it has no pertinence to the OP's original post.

If the OP can post up some photos of what he does have we can probably assess better what he is dealing with and help him get things set up correctly if they are not already so.

 

[xk49]

But back to the original question: The funky 55-only draft tube is not something the OP would be encountering. He has a 327. So while interesting, it has no pertinence to the OP's original post.

If the OP can post up some photos of what he does have we can probably assess better what he is dealing with and help him get things set up correctly if they are not already so.

Here's a couple of pictures. There is definitely a hose from the back of the block and it connects to the back of the intake manifold. Red arrow points to the draft(?) tube. Other tube is for brake booster.. The oil filler cap is vented.

In the first picture you can see there's a two inch section of rubber hose from the fitting on the block that connects to a silver/brass piece about 1 1/2" long then another longer tube from the silver inline fitting to the back of the intake manifold.. Is this a PCV fitting?

 

[Rich-L79]

If the pipe off the back of the block connects to the intake manifold (for vacuum) and the oil fill cap is vented and has some kind of filter material (most likely steel wool looking stuff at least), you have the system you need. However, I'd think it would be better if there was a PCV valve in the tube from the block to the intake manifold. The filter material in the vented cap should be cleaned and oiled occasionally.

 

[dyno jonn]

Hard to tell even after blowing up the picture, but there may be a PCV valve in the rear hose just to the right of the fitting that is bolted to the block.

 

[xk49]

Hard to tell even after blowing up the picture, but there may be a PCV valve in the rear hose just to the right of the fitting that is bolted to the block.

Yeah, that's what I'm thinking, because why would there be an interupt in the rubber hose.

 

[Rich-L79]

For all I know, that doohickey bolted into the hole at the back of the block could be a PCV valve of some sort.

 

[DZAUTO]

------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------- Is this a PCV fitting?

That is EXACTLY what it looks like to me. That was a common method of plumbing a PCV system.